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- 1. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionString Theory: Explanation and Fundamentalism Ioan Muntean Department of Philosophy Purdue University–Indiana University, Fort Wayne Philosophy of Science Association Meeting, Montreal, November 2010 Ioan Muntean String Theory: Explanation and Fundamentalism
- 2. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionTwo pathways towards Quantum Gravity (QG) Ioan Muntean String Theory: Explanation and Fundamentalism
- 3. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionTwo pathways towards Quantum Gravity (QG) 1 Find answers (new or right) to perennial philosophical problems in QG (“Philosophical centrism”) Ioan Muntean String Theory: Explanation and Fundamentalism
- 4. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionTwo pathways towards Quantum Gravity (QG) 1 Find answers (new or right) to perennial philosophical problems in QG (“Philosophical centrism”) 2 Analyze QG as scientiﬁc theories or, better, programs (“Philosophical analysis”) Ioan Muntean String Theory: Explanation and Fundamentalism
- 5. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionTwo pathways towards Quantum Gravity (QG) 1 Find answers (new or right) to perennial philosophical problems in QG (“Philosophical centrism”) 2 Analyze QG as scientiﬁc theories or, better, programs (“Philosophical analysis”) 1 ambitious and reformist (integrated in a form of scientism). Useful for metaphysics Ioan Muntean String Theory: Explanation and Fundamentalism
- 6. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionTwo pathways towards Quantum Gravity (QG) 1 Find answers (new or right) to perennial philosophical problems in QG (“Philosophical centrism”) 2 Analyze QG as scientiﬁc theories or, better, programs (“Philosophical analysis”) 1 ambitious and reformist (integrated in a form of scientism). Useful for metaphysics 2 useful in philosophy of science/physics. Can be normative ... Ioan Muntean String Theory: Explanation and Fundamentalism
- 7. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1 Philosophical centrism Ioan Muntean String Theory: Explanation and Fundamentalism
- 8. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1 Philosophical centrism Most QG programs say something special about our old metaphysical concepts: Ioan Muntean String Theory: Explanation and Fundamentalism
- 9. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1 Philosophical centrism Most QG programs say something special about our old metaphysical concepts: the nature of spacetime, space or time Ioan Muntean String Theory: Explanation and Fundamentalism
- 10. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1 Philosophical centrism Most QG programs say something special about our old metaphysical concepts: the nature of spacetime, space or time the measurement problem Ioan Muntean String Theory: Explanation and Fundamentalism
- 11. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1 Philosophical centrism Most QG programs say something special about our old metaphysical concepts: the nature of spacetime, space or time the measurement problem the ultimate nature of objects/processes/events in the world Ioan Muntean String Theory: Explanation and Fundamentalism
- 12. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1 Philosophical centrism Most QG programs say something special about our old metaphysical concepts: the nature of spacetime, space or time the measurement problem the ultimate nature of objects/processes/events in the world Ioan Muntean String Theory: Explanation and Fundamentalism
- 13. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1 Philosophical centrism Most QG programs say something special about our old metaphysical concepts: the nature of spacetime, space or time the measurement problem the ultimate nature of objects/processes/events in the world Question Q1 Which Quantum Gravity program provides the best answer to the metaphysical question X? Ioan Muntean String Theory: Explanation and Fundamentalism
- 14. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1 Philosophical centrism Most QG programs say something special about our old metaphysical concepts: the nature of spacetime, space or time the measurement problem the ultimate nature of objects/processes/events in the world Question Q1 Which Quantum Gravity program provides the best answer to the metaphysical question X? In most cases, QG are prescriptive in respect of time, space, quantization etc. Ioan Muntean String Theory: Explanation and Fundamentalism
- 15. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1 Philosophical centrism Most QG programs say something special about our old metaphysical concepts: the nature of spacetime, space or time the measurement problem the ultimate nature of objects/processes/events in the world Question Q1 Which Quantum Gravity program provides the best answer to the metaphysical question X? In most cases, QG are prescriptive in respect of time, space, quantization etc. ??????? Ioan Muntean String Theory: Explanation and Fundamentalism
- 16. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionPhilosophers should be doing this! Sometimes philosophers help with insights in the problem of space, time, change, dynamics, etc. Ioan Muntean String Theory: Explanation and Fundamentalism
- 17. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionPhilosophers should be doing this! Sometimes philosophers help with insights in the problem of space, time, change, dynamics, etc. Ioan Muntean String Theory: Explanation and Fundamentalism
- 18. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionPhilosophers should be doing this! Sometimes philosophers help with insights in the problem of space, time, change, dynamics, etc. “General relativity and quantum ﬁeld theory are based on some profound insights about the nature of reality. These insights are crystallized in the form of mathematics, but there is a limit to how much progress we can make by just playing around with this mathematics. We need to go back to the insights behind general relativity and quantum ﬁeld theory, learn to hold them together in our minds, and dare to imagine a world more strange, more beautiful, but ultimately more reasonable than our current theories of it. For this daunting task, philosophical reﬂection is bound toTheory:of help.” (J. Baez Ioan Muntean String be Explanation and Fundamentalism
- 19. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1’. Yet another philosophical centrism Strengthen an existing metaphysics by interpreting QG Ioan Muntean String Theory: Explanation and Fundamentalism
- 20. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1’. Yet another philosophical centrism Strengthen an existing metaphysics by interpreting QG Structural Realism and QG Ioan Muntean String Theory: Explanation and Fundamentalism
- 21. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1’. Yet another philosophical centrism Strengthen an existing metaphysics by interpreting QG Structural Realism and QG Identity and individuation of objects and QG (compare and contrast with QM and QFT) Ioan Muntean String Theory: Explanation and Fundamentalism
- 22. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1’. Yet another philosophical centrism Strengthen an existing metaphysics by interpreting QG Structural Realism and QG Identity and individuation of objects and QG (compare and contrast with QM and QFT) Part-whole relations and QG. Ioan Muntean String Theory: Explanation and Fundamentalism
- 23. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion1’. Yet another philosophical centrism Strengthen an existing metaphysics by interpreting QG Structural Realism and QG Identity and individuation of objects and QG (compare and contrast with QM and QFT) Part-whole relations and QG. For Structural Realism and QG see ? Ioan Muntean String Theory: Explanation and Fundamentalism
- 24. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion2. Philosophical pathways to QG Ioan Muntean String Theory: Explanation and Fundamentalism
- 25. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion2. Philosophical pathways to QG Which QG program is the best as a scientiﬁc endeavor? Ioan Muntean String Theory: Explanation and Fundamentalism
- 26. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion2. Philosophical pathways to QG Which QG program is the best as a scientiﬁc endeavor? Ioan Muntean String Theory: Explanation and Fundamentalism
- 27. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion2. Philosophical pathways to QG Which QG program is the best as a scientiﬁc endeavor? Question Q2 Which QG program is the best in respect of a given virtue V? Ioan Muntean String Theory: Explanation and Fundamentalism
- 28. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion2. Philosophical pathways to QG Which QG program is the best as a scientiﬁc endeavor? Question Q2 Which QG program is the best in respect of a given virtue V? Question Q2’ Which Quantum Gravity program has the drawback D? Ioan Muntean String Theory: Explanation and Fundamentalism
- 29. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion2. Philosophical pathways to QG Which QG program is the best as a scientiﬁc endeavor? Question Q2 Which QG program is the best in respect of a given virtue V? Question Q2’ Which Quantum Gravity program has the drawback D? This is discussed by fewer philosophers ??? Ioan Muntean String Theory: Explanation and Fundamentalism
- 30. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and Conclusion2. Philosophical pathways to QG Which QG program is the best as a scientiﬁc endeavor? Question Q2 Which QG program is the best in respect of a given virtue V? Question Q2’ Which Quantum Gravity program has the drawback D? This is discussed by fewer philosophers ??? I plan to follow something similar here Ioan Muntean String Theory: Explanation and Fundamentalism
- 31. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope Ioan Muntean String Theory: Explanation and Fundamentalism
- 32. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Ioan Muntean String Theory: Explanation and Fundamentalism
- 33. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Ioan Muntean String Theory: Explanation and Fundamentalism
- 34. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Dimensions of success of theories: Ioan Muntean String Theory: Explanation and Fundamentalism
- 35. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Dimensions of success of theories: 1 Empirical conﬁrmation (preferably direct) Ioan Muntean String Theory: Explanation and Fundamentalism
- 36. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Dimensions of success of theories: 1 Empirical conﬁrmation (preferably direct) 2 Predictive success (preferably novel) Ioan Muntean String Theory: Explanation and Fundamentalism
- 37. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Dimensions of success of theories: 1 Empirical conﬁrmation (preferably direct) 2 Predictive success (preferably novel) 3 Non-empirical virtues: uniﬁcation, explanation, elegance, simplicity Ioan Muntean String Theory: Explanation and Fundamentalism
- 38. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Dimensions of success of theories: 1 Empirical conﬁrmation (preferably direct) 2 Predictive success (preferably novel) 3 Non-empirical virtues: uniﬁcation, explanation, elegance, simplicity 4 Problem solving (preferably real problems), etc. Ioan Muntean String Theory: Explanation and Fundamentalism
- 39. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Dimensions of success of theories: 1 Empirical conﬁrmation (preferably direct) 2 Predictive success (preferably novel) 3 Non-empirical virtues: uniﬁcation, explanation, elegance, simplicity 4 Problem solving (preferably real problems), etc. 5 Fecundity Ioan Muntean String Theory: Explanation and Fundamentalism
- 40. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Dimensions of success of theories: 1 Empirical conﬁrmation (preferably direct) 2 Predictive success (preferably novel) 3 Non-empirical virtues: uniﬁcation, explanation, elegance, simplicity 4 Problem solving (preferably real problems), etc. 5 Fecundity 6 Meshing well with other scientiﬁc theories Ioan Muntean String Theory: Explanation and Fundamentalism
- 41. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Dimensions of success of theories: 1 Empirical conﬁrmation (preferably direct) 2 Predictive success (preferably novel) 3 Non-empirical virtues: uniﬁcation, explanation, elegance, simplicity 4 Problem solving (preferably real problems), etc. 5 Fecundity 6 Meshing well with other scientiﬁc theories None of them is necessary and suﬃcient. Ioan Muntean String Theory: Explanation and Fundamentalism
- 42. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Dimensions of success of theories: 1 Empirical conﬁrmation (preferably direct) 2 Predictive success (preferably novel) 3 Non-empirical virtues: uniﬁcation, explanation, elegance, simplicity 4 Problem solving (preferably real problems), etc. 5 Fecundity 6 Meshing well with other scientiﬁc theories None of them is necessary and suﬃcient. Ioan Muntean String Theory: Explanation and Fundamentalism
- 43. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA narrow scope I give up the comparative aspects of Q2 and Q2’and focus on one QG program Question Is string theory a successful QG program? Dimensions of success of theories: 1 Empirical conﬁrmation (preferably direct) 2 Predictive success (preferably novel) 3 Non-empirical virtues: uniﬁcation, explanation, elegance, simplicity 4 Problem solving (preferably real problems), etc. 5 Fecundity 6 Meshing well with other scientiﬁc theories None of them is necessary and suﬃcient. Ioan Muntean String Theory: Explanation and Fundamentalism
- 44. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory Ioan Muntean String Theory: Explanation and Fundamentalism
- 45. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: Ioan Muntean String Theory: Explanation and Fundamentalism
- 46. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: the ultraviolet divergences of General Relativity and of Standard Model. Ioan Muntean String Theory: Explanation and Fundamentalism
- 47. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: the ultraviolet divergences of General Relativity and of Standard Model. no dimensionless free parameters. Ioan Muntean String Theory: Explanation and Fundamentalism
- 48. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: the ultraviolet divergences of General Relativity and of Standard Model. no dimensionless free parameters. Is the dominant research program in quantum gravity (QG) Ioan Muntean String Theory: Explanation and Fundamentalism
- 49. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: the ultraviolet divergences of General Relativity and of Standard Model. no dimensionless free parameters. Is the dominant research program in quantum gravity (QG) Is the (leading?) contender for a theory of everything: Ioan Muntean String Theory: Explanation and Fundamentalism
- 50. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: the ultraviolet divergences of General Relativity and of Standard Model. no dimensionless free parameters. Is the dominant research program in quantum gravity (QG) Is the (leading?) contender for a theory of everything: Advertised as: “a single theory that, in principle is capable of describing all phenomena” ((?, ix)). Ioan Muntean String Theory: Explanation and Fundamentalism
- 51. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: the ultraviolet divergences of General Relativity and of Standard Model. no dimensionless free parameters. Is the dominant research program in quantum gravity (QG) Is the (leading?) contender for a theory of everything: Advertised as: “a single theory that, in principle is capable of describing all phenomena” ((?, ix)). Heavily advertised in popularizing literature, perhaps the best known quantum gravity program Ioan Muntean String Theory: Explanation and Fundamentalism
- 52. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: the ultraviolet divergences of General Relativity and of Standard Model. no dimensionless free parameters. Is the dominant research program in quantum gravity (QG) Is the (leading?) contender for a theory of everything: Advertised as: “a single theory that, in principle is capable of describing all phenomena” ((?, ix)). Heavily advertised in popularizing literature, perhaps the best known quantum gravity program Could tell us new stories about the world: Ioan Muntean String Theory: Explanation and Fundamentalism
- 53. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: the ultraviolet divergences of General Relativity and of Standard Model. no dimensionless free parameters. Is the dominant research program in quantum gravity (QG) Is the (leading?) contender for a theory of everything: Advertised as: “a single theory that, in principle is capable of describing all phenomena” ((?, ix)). Heavily advertised in popularizing literature, perhaps the best known quantum gravity program Could tell us new stories about the world: can talk evolution of the universe before the Big Bang (interpreted as a collision of branes) Ioan Muntean String Theory: Explanation and Fundamentalism
- 54. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: the ultraviolet divergences of General Relativity and of Standard Model. no dimensionless free parameters. Is the dominant research program in quantum gravity (QG) Is the (leading?) contender for a theory of everything: Advertised as: “a single theory that, in principle is capable of describing all phenomena” ((?, ix)). Heavily advertised in popularizing literature, perhaps the best known quantum gravity program Could tell us new stories about the world: can talk evolution of the universe before the Big Bang (interpreted as a collision of branes) explains facts about black holes, dark matter etc. Ioan Muntean String Theory: Explanation and Fundamentalism
- 55. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons to . . . love string theory It solves some problems: the ultraviolet divergences of General Relativity and of Standard Model. no dimensionless free parameters. Is the dominant research program in quantum gravity (QG) Is the (leading?) contender for a theory of everything: Advertised as: “a single theory that, in principle is capable of describing all phenomena” ((?, ix)). Heavily advertised in popularizing literature, perhaps the best known quantum gravity program Could tell us new stories about the world: can talk evolution of the universe before the Big Bang (interpreted as a collision of branes) explains facts about black holes, dark matter etc. But these are promises and prospective Explanation and Fundamentalism Ioan Muntean String Theory: undertakings
- 56. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionMore reasons to. . . love ST Ioan Muntean String Theory: Explanation and Fundamentalism
- 57. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionMore reasons to. . . love ST It is “science in the making” Ioan Muntean String Theory: Explanation and Fundamentalism
- 58. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionMore reasons to. . . love ST It is “science in the making” It is mathematically fertile and can provide “mathematical predictions” (?) Ioan Muntean String Theory: Explanation and Fundamentalism
- 59. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionMore reasons to. . . love ST It is “science in the making” It is mathematically fertile and can provide “mathematical predictions” (?) It is open to interpretive questions (?) Ioan Muntean String Theory: Explanation and Fundamentalism
- 60. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionMore reasons to. . . love ST It is “science in the making” It is mathematically fertile and can provide “mathematical predictions” (?) It is open to interpretive questions (?) As any other QG, it is a fertile middle ground between philosophy (metaphysics and epistemology) and theoretical physics Ioan Muntean String Theory: Explanation and Fundamentalism
- 61. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionAmendments Ioan Muntean String Theory: Explanation and Fundamentalism
- 62. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionAmendments String theory does not have the features of a scientiﬁc theory Ioan Muntean String Theory: Explanation and Fundamentalism
- 63. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionAmendments String theory does not have the features of a scientiﬁc theory Call it a program/direction of research, not a theory Ioan Muntean String Theory: Explanation and Fundamentalism
- 64. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionAmendments String theory does not have the features of a scientiﬁc theory Call it a program/direction of research, not a theory Interpret it as a collection of mathematical models Ioan Muntean String Theory: Explanation and Fundamentalism
- 65. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionAmendments String theory does not have the features of a scientiﬁc theory Call it a program/direction of research, not a theory Interpret it as a collection of mathematical models 1 each model is false and has intentional falsities inserted Ioan Muntean String Theory: Explanation and Fundamentalism
- 66. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionAmendments String theory does not have the features of a scientiﬁc theory Call it a program/direction of research, not a theory Interpret it as a collection of mathematical models 1 each model is false and has intentional falsities inserted 2 the model does not latch onto the world Ioan Muntean String Theory: Explanation and Fundamentalism
- 67. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionAmendments String theory does not have the features of a scientiﬁc theory Call it a program/direction of research, not a theory Interpret it as a collection of mathematical models 1 each model is false and has intentional falsities inserted 2 the model does not latch onto the world string theory does not explains facts, at least not directly. Ioan Muntean String Theory: Explanation and Fundamentalism
- 68. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionAmendments String theory does not have the features of a scientiﬁc theory Call it a program/direction of research, not a theory Interpret it as a collection of mathematical models 1 each model is false and has intentional falsities inserted 2 the model does not latch onto the world string theory does not explains facts, at least not directly. it may predict mathematical facts or even provide mathematical results Ioan Muntean String Theory: Explanation and Fundamentalism
- 69. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons not to. . . love it Ioan Muntean String Theory: Explanation and Fundamentalism
- 70. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons not to. . . love it String theory is a “gloriﬁed” QFT (and nothing more) Ioan Muntean String Theory: Explanation and Fundamentalism
- 71. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons not to. . . love it String theory is a “gloriﬁed” QFT (and nothing more) “a chip of the same block” as QFT has its own skeleton in the closet Ioan Muntean String Theory: Explanation and Fundamentalism
- 72. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons not to. . . love it String theory is a “gloriﬁed” QFT (and nothing more) “a chip of the same block” as QFT has its own skeleton in the closet String theory: Ioan Muntean String Theory: Explanation and Fundamentalism
- 73. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons not to. . . love it String theory is a “gloriﬁed” QFT (and nothing more) “a chip of the same block” as QFT has its own skeleton in the closet String theory: is background dependent (Smolin, Rovelli, Penrose) Ioan Muntean String Theory: Explanation and Fundamentalism
- 74. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons not to. . . love it String theory is a “gloriﬁed” QFT (and nothing more) “a chip of the same block” as QFT has its own skeleton in the closet String theory: is background dependent (Smolin, Rovelli, Penrose) does not seem to address deep philosophical issues (?) Ioan Muntean String Theory: Explanation and Fundamentalism
- 75. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons not to. . . love it String theory is a “gloriﬁed” QFT (and nothing more) “a chip of the same block” as QFT has its own skeleton in the closet String theory: is background dependent (Smolin, Rovelli, Penrose) does not seem to address deep philosophical issues (?) never solved or addressed the measurement problem Ioan Muntean String Theory: Explanation and Fundamentalism
- 76. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons not to. . . love it String theory is a “gloriﬁed” QFT (and nothing more) “a chip of the same block” as QFT has its own skeleton in the closet String theory: is background dependent (Smolin, Rovelli, Penrose) does not seem to address deep philosophical issues (?) never solved or addressed the measurement problem All known string theories are perturbation theories Ioan Muntean String Theory: Explanation and Fundamentalism
- 77. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionSome reasons not to. . . love it String theory is a “gloriﬁed” QFT (and nothing more) “a chip of the same block” as QFT has its own skeleton in the closet String theory: is background dependent (Smolin, Rovelli, Penrose) does not seem to address deep philosophical issues (?) never solved or addressed the measurement problem All known string theories are perturbation theories String solutions are unstable (?) Ioan Muntean String Theory: Explanation and Fundamentalism
- 78. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA reason to hate it: background dependency Ioan Muntean String Theory: Explanation and Fundamentalism
- 79. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA reason to hate it: background dependency ST presupposes a spacetime background and by this it deﬁes general relativity (???) Ioan Muntean String Theory: Explanation and Fundamentalism
- 80. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA reason to hate it: background dependency ST presupposes a spacetime background and by this it deﬁes general relativity (???) Philosophers do not like this dependency either (See Introduction to ?) Ioan Muntean String Theory: Explanation and Fundamentalism
- 81. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA reason to hate it: background dependency ST presupposes a spacetime background and by this it deﬁes general relativity (???) Philosophers do not like this dependency either (See Introduction to ?) So does QFT, it involves a ﬁxed spacetime geometry (a priori?) Ioan Muntean String Theory: Explanation and Fundamentalism
- 82. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA reason to hate it: background dependency ST presupposes a spacetime background and by this it deﬁes general relativity (???) Philosophers do not like this dependency either (See Introduction to ?) So does QFT, it involves a ﬁxed spacetime geometry (a priori?) But this is against the very principle of general relativity. Ioan Muntean String Theory: Explanation and Fundamentalism
- 83. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA reason to hate it: background dependency ST presupposes a spacetime background and by this it deﬁes general relativity (???) Philosophers do not like this dependency either (See Introduction to ?) So does QFT, it involves a ﬁxed spacetime geometry (a priori?) But this is against the very principle of general relativity. In String Theory geometry is not dynamical anymore. Ioan Muntean String Theory: Explanation and Fundamentalism
- 84. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionA reason to hate it: background dependency ST presupposes a spacetime background and by this it deﬁes general relativity (???) Philosophers do not like this dependency either (See Introduction to ?) So does QFT, it involves a ﬁxed spacetime geometry (a priori?) But this is against the very principle of general relativity. In String Theory geometry is not dynamical anymore. It is like the “unmoved mover” or the ether. Ioan Muntean String Theory: Explanation and Fundamentalism
- 85. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionThe prodigal ST Ioan Muntean String Theory: Explanation and Fundamentalism
- 86. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionThe prodigal ST “What is very frustrating is that . . . string theory does not seem to fully incorporate the basic lesson of GR, which is that space and time are dynamical rather than ﬁxed, and relational rather than absolute . . . all that happens is that some strings move against this ﬁxed background and interact with one another.” ((?, 159)) Ioan Muntean String Theory: Explanation and Fundamentalism
- 87. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionThe prodigal ST “What is very frustrating is that . . . string theory does not seem to fully incorporate the basic lesson of GR, which is that space and time are dynamical rather than ﬁxed, and relational rather than absolute . . . all that happens is that some strings move against this ﬁxed background and interact with one another.” ((?, 159)) Roughly speaking, ST replicates the mistake of Newtonian physics and overlooks some central achievements of GR. Ioan Muntean String Theory: Explanation and Fundamentalism
- 88. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionThe prodigal ST “What is very frustrating is that . . . string theory does not seem to fully incorporate the basic lesson of GR, which is that space and time are dynamical rather than ﬁxed, and relational rather than absolute . . . all that happens is that some strings move against this ﬁxed background and interact with one another.” ((?, 159)) Roughly speaking, ST replicates the mistake of Newtonian physics and overlooks some central achievements of GR. i.e. it does mesh well with mature/successful/well-accepted scientiﬁc theories. Ioan Muntean String Theory: Explanation and Fundamentalism
- 89. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionBleak philosophy of string theory: conﬁrmation andprediction Is ST conﬁrmed directly? Ioan Muntean String Theory: Explanation and Fundamentalism
- 90. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionBleak philosophy of string theory: conﬁrmation andprediction Is ST conﬁrmed directly? No, it is not. Ioan Muntean String Theory: Explanation and Fundamentalism
- 91. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionBleak philosophy of string theory: conﬁrmation andprediction Is ST conﬁrmed directly? No, it is not. Is ST successful in providing novel predictions? Ioan Muntean String Theory: Explanation and Fundamentalism
- 92. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionBleak philosophy of string theory: conﬁrmation andprediction Is ST conﬁrmed directly? No, it is not. Is ST successful in providing novel predictions? No, it is not. Ioan Muntean String Theory: Explanation and Fundamentalism
- 93. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionBleak philosophy of string theory: conﬁrmation andprediction Is ST conﬁrmed directly? No, it is not. Is ST successful in providing novel predictions? No, it is not. Some predictions are in sight in “string cosmology” or stringy black holes Ioan Muntean String Theory: Explanation and Fundamentalism
- 94. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionBleak philosophy of string theory: conﬁrmation andprediction Is ST conﬁrmed directly? No, it is not. Is ST successful in providing novel predictions? No, it is not. Some predictions are in sight in “string cosmology” or stringy black holes I would not apply a “naive falsiﬁcationism” to string theory. Ioan Muntean String Theory: Explanation and Fundamentalism
- 95. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionApply GOF falsiﬁcationism to string theory? Ioan Muntean String Theory: Explanation and Fundamentalism
- 96. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionApply GOF falsiﬁcationism to string theory? No data, no falsiﬁcation, no science Ioan Muntean String Theory: Explanation and Fundamentalism
- 97. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionApply GOF falsiﬁcationism to string theory? No data, no falsiﬁcation, no science Hence string theory is closer to: Ioan Muntean String Theory: Explanation and Fundamentalism
- 98. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionApply GOF falsiﬁcationism to string theory? No data, no falsiﬁcation, no science Hence string theory is closer to: Mathematics Ioan Muntean String Theory: Explanation and Fundamentalism
- 99. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionApply GOF falsiﬁcationism to string theory? No data, no falsiﬁcation, no science Hence string theory is closer to: Mathematics Metaphysics Ioan Muntean String Theory: Explanation and Fundamentalism
- 100. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionApply GOF falsiﬁcationism to string theory? No data, no falsiﬁcation, no science Hence string theory is closer to: Mathematics Metaphysics Speculation Ioan Muntean String Theory: Explanation and Fundamentalism
- 101. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionApply GOF falsiﬁcationism to string theory? No data, no falsiﬁcation, no science Hence string theory is closer to: Mathematics Metaphysics Speculation Mysticism, new-age cults or even religion (it creates its own lingo). Ioan Muntean String Theory: Explanation and Fundamentalism
- 102. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionApply GOF falsiﬁcationism to string theory? No data, no falsiﬁcation, no science Hence string theory is closer to: Mathematics Metaphysics Speculation Mysticism, new-age cults or even religion (it creates its own lingo). Some deemed ST (and QG) as “postmodern physics” (Nambu) Ioan Muntean String Theory: Explanation and Fundamentalism
- 103. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionApply GOF falsiﬁcationism to string theory? No data, no falsiﬁcation, no science Hence string theory is closer to: Mathematics Metaphysics Speculation Mysticism, new-age cults or even religion (it creates its own lingo). Some deemed ST (and QG) as “postmodern physics” (Nambu) Several physicists aired these worries: L. Smolin, P. Woit, R. Penrose Ioan Muntean String Theory: Explanation and Fundamentalism
- 104. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionApply GOF falsiﬁcationism to string theory? No data, no falsiﬁcation, no science Hence string theory is closer to: Mathematics Metaphysics Speculation Mysticism, new-age cults or even religion (it creates its own lingo). Some deemed ST (and QG) as “postmodern physics” (Nambu) Several physicists aired these worries: L. Smolin, P. Woit, R. Penrose Ioan Muntean String Theory: Explanation and Fundamentalism
- 105. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionExperimental agnosticism Stay agnostic about its direct experimental conﬁrmation Ioan Muntean String Theory: Explanation and Fundamentalism
- 106. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionExperimental agnosticism Stay agnostic about its direct experimental conﬁrmation Ioan Muntean String Theory: Explanation and Fundamentalism
- 107. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionExperimental agnosticism Stay agnostic about its direct experimental conﬁrmation “Test me if you can!” Ioan Muntean String Theory: Explanation and Fundamentalism
- 108. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionExperimental agnosticism Stay agnostic about its direct experimental conﬁrmation “Test me if you can!” Credits go to http://icanhascheeseburger.com Ioan Muntean String Theory: Explanation and Fundamentalism
- 109. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues Ioan Muntean String Theory: Explanation and Fundamentalism
- 110. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues What theoretical dimensions of scientiﬁc success are known? Ioan Muntean String Theory: Explanation and Fundamentalism
- 111. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues What theoretical dimensions of scientiﬁc success are known? 1 Uniﬁcation Ioan Muntean String Theory: Explanation and Fundamentalism
- 112. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues What theoretical dimensions of scientiﬁc success are known? 1 Uniﬁcation 2 Explanation Ioan Muntean String Theory: Explanation and Fundamentalism
- 113. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues What theoretical dimensions of scientiﬁc success are known? 1 Uniﬁcation 2 Explanation 3 Elegancy, Cohesion, Beauty, Simplicity, you name it. . . Ioan Muntean String Theory: Explanation and Fundamentalism
- 114. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues What theoretical dimensions of scientiﬁc success are known? 1 Uniﬁcation 2 Explanation 3 Elegancy, Cohesion, Beauty, Simplicity, you name it. . . 4 Problem Solving Ioan Muntean String Theory: Explanation and Fundamentalism
- 115. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues What theoretical dimensions of scientiﬁc success are known? 1 Uniﬁcation 2 Explanation 3 Elegancy, Cohesion, Beauty, Simplicity, you name it. . . 4 Problem Solving 1 is obvious and recognized as such (but deserves attention, too) Ioan Muntean String Theory: Explanation and Fundamentalism
- 116. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues What theoretical dimensions of scientiﬁc success are known? 1 Uniﬁcation 2 Explanation 3 Elegancy, Cohesion, Beauty, Simplicity, you name it. . . 4 Problem Solving 1 is obvious and recognized as such (but deserves attention, too) 3 diﬃcult to deﬁne, vague, ambiguous Ioan Muntean String Theory: Explanation and Fundamentalism
- 117. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues What theoretical dimensions of scientiﬁc success are known? 1 Uniﬁcation 2 Explanation 3 Elegancy, Cohesion, Beauty, Simplicity, you name it. . . 4 Problem Solving 1 is obvious and recognized as such (but deserves attention, too) 3 diﬃcult to deﬁne, vague, ambiguous 4 is a interesting topic in itself (Ex: string and anomalies) Ioan Muntean String Theory: Explanation and Fundamentalism
- 118. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues What theoretical dimensions of scientiﬁc success are known? 1 Uniﬁcation 2 Explanation 3 Elegancy, Cohesion, Beauty, Simplicity, you name it. . . 4 Problem Solving 1 is obvious and recognized as such (but deserves attention, too) 3 diﬃcult to deﬁne, vague, ambiguous 4 is a interesting topic in itself (Ex: string and anomalies) Here I tackle 2 and relatedly, 1. Ioan Muntean String Theory: Explanation and Fundamentalism
- 119. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionLess bleak philosophy of string theory: some virtues What theoretical dimensions of scientiﬁc success are known? 1 Uniﬁcation 2 Explanation 3 Elegancy, Cohesion, Beauty, Simplicity, you name it. . . 4 Problem Solving 1 is obvious and recognized as such (but deserves attention, too) 3 diﬃcult to deﬁne, vague, ambiguous 4 is a interesting topic in itself (Ex: string and anomalies) Here I tackle 2 and relatedly, 1. Why 2? Ioan Muntean String Theory: Explanation and Fundamentalism
- 120. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionDoes string theory “latch onto reality”? If so, how? Ioan Muntean String Theory: Explanation and Fundamentalism
- 121. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionDoes string theory “latch onto reality”? If so, how? If string explanation is succesful, one can try to run an “inference from the best explanation”. Ioan Muntean String Theory: Explanation and Fundamentalism
- 122. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionDoes string theory “latch onto reality”? If so, how? If string explanation is succesful, one can try to run an “inference from the best explanation”. But this inference needs to be precedeed by an analysis of the surplus structure of string theory. Ioan Muntean String Theory: Explanation and Fundamentalism
- 123. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionDoes string theory “latch onto reality”? If so, how? If string explanation is succesful, one can try to run an “inference from the best explanation”. But this inference needs to be precedeed by an analysis of the surplus structure of string theory. Other related questions: Ioan Muntean String Theory: Explanation and Fundamentalism
- 124. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionDoes string theory “latch onto reality”? If so, how? If string explanation is succesful, one can try to run an “inference from the best explanation”. But this inference needs to be precedeed by an analysis of the surplus structure of string theory. Other related questions: Is ST or is it not “non-referential”? Ioan Muntean String Theory: Explanation and Fundamentalism
- 125. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionDoes string theory “latch onto reality”? If so, how? If string explanation is succesful, one can try to run an “inference from the best explanation”. But this inference needs to be precedeed by an analysis of the surplus structure of string theory. Other related questions: Is ST or is it not “non-referential”? Do we have reasons to believe in the reality of strings (or branes or whatever?) Ioan Muntean String Theory: Explanation and Fundamentalism
- 126. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionDoes string theory “latch onto reality”? If so, how? If string explanation is succesful, one can try to run an “inference from the best explanation”. But this inference needs to be precedeed by an analysis of the surplus structure of string theory. Other related questions: Is ST or is it not “non-referential”? Do we have reasons to believe in the reality of strings (or branes or whatever?) What reason do we have to embrace a “string realism”? Ioan Muntean String Theory: Explanation and Fundamentalism
- 127. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionWhat is needed in the metaphysics of string theory? Ioan Muntean String Theory: Explanation and Fundamentalism
- 128. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionWhat is needed in the metaphysics of string theory? As in QM or QFT, we cannot “read oﬀ” the ontology from their equations Ioan Muntean String Theory: Explanation and Fundamentalism
- 129. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionWhat is needed in the metaphysics of string theory? As in QM or QFT, we cannot “read oﬀ” the ontology from their equations Hard to diﬀerentiate the surplus from the real elements of the theory. Ioan Muntean String Theory: Explanation and Fundamentalism
- 130. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionWhat is needed in the metaphysics of string theory? As in QM or QFT, we cannot “read oﬀ” the ontology from their equations Hard to diﬀerentiate the surplus from the real elements of the theory. We cannot cherry-pick the equations and interpret them Ioan Muntean String Theory: Explanation and Fundamentalism
- 131. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionWhat is needed in the metaphysics of string theory? As in QM or QFT, we cannot “read oﬀ” the ontology from their equations Hard to diﬀerentiate the surplus from the real elements of the theory. We cannot cherry-pick the equations and interpret them Diﬀerentiate explanatory ﬁctions from real explanatory entities Ioan Muntean String Theory: Explanation and Fundamentalism
- 132. Philosophy and Quantum Gravity programs Explanation and string theory Two stances The nutshell version of string theory Philosophy of Science and String Theory Some case studies of string explanations String metaphysics? Rejoinders and ConclusionWhat is needed in the metaphysics of string theory? As in QM or QFT, we cannot “read oﬀ” the ontology from their equations Hard to diﬀerentiate the surplus from the real elements of the theory. We cannot cherry-pick the equations and interpret them Diﬀerentiate explanatory ﬁctions from real explanatory entities Perhaps we need some lessons from mainstream metaphysics about fundamentality. Ioan Muntean String Theory: Explanation and Fundamentalism
- 133. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Ioan Muntean String Theory: Explanation and Fundamentalism
- 134. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Look at the explanatory store of String Theory: what is explained? Ioan Muntean String Theory: Explanation and Fundamentalism
- 135. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Look at the explanatory store of String Theory: what is explained? Primarily, I argue, string theory explains features of other theories: Ioan Muntean String Theory: Explanation and Fundamentalism
- 136. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Look at the explanatory store of String Theory: what is explained? Primarily, I argue, string theory explains features of other theories: 1 Constants and Parameters: Newton’s constant; Ioan Muntean String Theory: Explanation and Fundamentalism
- 137. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Look at the explanatory store of String Theory: what is explained? Primarily, I argue, string theory explains features of other theories: 1 Constants and Parameters: Newton’s constant; 2 Structures: the fermion-boson duality of the Standard Model, the group structure of the Standard Model; Ioan Muntean String Theory: Explanation and Fundamentalism
- 138. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Look at the explanatory store of String Theory: what is explained? Primarily, I argue, string theory explains features of other theories: 1 Constants and Parameters: Newton’s constant; 2 Structures: the fermion-boson duality of the Standard Model, the group structure of the Standard Model; 3 The gauge nature of General Relativity; Ioan Muntean String Theory: Explanation and Fundamentalism
- 139. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Look at the explanatory store of String Theory: what is explained? Primarily, I argue, string theory explains features of other theories: 1 Constants and Parameters: Newton’s constant; 2 Structures: the fermion-boson duality of the Standard Model, the group structure of the Standard Model; 3 The gauge nature of General Relativity; 4 Facts which are taken as “brute” in other theories; Ioan Muntean String Theory: Explanation and Fundamentalism
- 140. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Look at the explanatory store of String Theory: what is explained? Primarily, I argue, string theory explains features of other theories: 1 Constants and Parameters: Newton’s constant; 2 Structures: the fermion-boson duality of the Standard Model, the group structure of the Standard Model; 3 The gauge nature of General Relativity; 4 Facts which are taken as “brute” in other theories; 5 Its own limitations: inconsistencies, incompleteness. Ioan Muntean String Theory: Explanation and Fundamentalism
- 141. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Look at the explanatory store of String Theory: what is explained? Primarily, I argue, string theory explains features of other theories: 1 Constants and Parameters: Newton’s constant; 2 Structures: the fermion-boson duality of the Standard Model, the group structure of the Standard Model; 3 The gauge nature of General Relativity; 4 Facts which are taken as “brute” in other theories; 5 Its own limitations: inconsistencies, incompleteness. At this stage, it does not directly explain facts about/from the world Ioan Muntean String Theory: Explanation and Fundamentalism
- 142. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Look at the explanatory store of String Theory: what is explained? Primarily, I argue, string theory explains features of other theories: 1 Constants and Parameters: Newton’s constant; 2 Structures: the fermion-boson duality of the Standard Model, the group structure of the Standard Model; 3 The gauge nature of General Relativity; 4 Facts which are taken as “brute” in other theories; 5 Its own limitations: inconsistencies, incompleteness. At this stage, it does not directly explain facts about/from the world Therefore, “string explanation” is mainly an inter-theoretical relation Ioan Muntean String Theory: Explanation and Fundamentalism
- 143. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionMy proposal Look at the explanatory store of String Theory: what is explained? Primarily, I argue, string theory explains features of other theories: 1 Constants and Parameters: Newton’s constant; 2 Structures: the fermion-boson duality of the Standard Model, the group structure of the Standard Model; 3 The gauge nature of General Relativity; 4 Facts which are taken as “brute” in other theories; 5 Its own limitations: inconsistencies, incompleteness. At this stage, it does not directly explain facts about/from the world Therefore, “string explanation” is mainly an inter-theoretical relation Ioan Muntean String Theory: Explanation and Fundamentalism
- 144. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. Ioan Muntean String Theory: Explanation and Fundamentalism
- 145. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Ioan Muntean String Theory: Explanation and Fundamentalism
- 146. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Option 1: The D-N model Ioan Muntean String Theory: Explanation and Fundamentalism
- 147. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Option 1: The D-N model Are there laws/generalizations in String Theory? Ioan Muntean String Theory: Explanation and Fundamentalism
- 148. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Option 1: The D-N model Are there laws/generalizations in String Theory? Do we have facts to “explain”? Ioan Muntean String Theory: Explanation and Fundamentalism
- 149. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Option 1: The D-N model Are there laws/generalizations in String Theory? Do we have facts to “explain”? Do we have facts to use in the D-N explanation? Ioan Muntean String Theory: Explanation and Fundamentalism
- 150. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Option 1: The D-N model Are there laws/generalizations in String Theory? Do we have facts to “explain”? Do we have facts to use in the D-N explanation? Arguably, string theory does not have principles or laws Ioan Muntean String Theory: Explanation and Fundamentalism
- 151. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Option 1: The D-N model Are there laws/generalizations in String Theory? Do we have facts to “explain”? Do we have facts to use in the D-N explanation? Arguably, string theory does not have principles or laws Option 2: Causal model of explanation Ioan Muntean String Theory: Explanation and Fundamentalism
- 152. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Option 1: The D-N model Are there laws/generalizations in String Theory? Do we have facts to “explain”? Do we have facts to use in the D-N explanation? Arguably, string theory does not have principles or laws Option 2: Causal model of explanation No chance to see causation at work at this level Ioan Muntean String Theory: Explanation and Fundamentalism
- 153. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Option 1: The D-N model Are there laws/generalizations in String Theory? Do we have facts to “explain”? Do we have facts to use in the D-N explanation? Arguably, string theory does not have principles or laws Option 2: Causal model of explanation No chance to see causation at work at this level Option 3: Mathematical explanations Ioan Muntean String Theory: Explanation and Fundamentalism
- 154. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Option 1: The D-N model Are there laws/generalizations in String Theory? Do we have facts to “explain”? Do we have facts to use in the D-N explanation? Arguably, string theory does not have principles or laws Option 2: Causal model of explanation No chance to see causation at work at this level Option 3: Mathematical explanations Option 4: Explanations based on uniﬁcation Ioan Muntean String Theory: Explanation and Fundamentalism
- 155. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionString Explanation: another bleak philosophy? Gut reaction: “nothing new under the Sun”! Integrate String explanations in the existing models of explanation. What kind of explanation is at work in string theory? Option 1: The D-N model Are there laws/generalizations in String Theory? Do we have facts to “explain”? Do we have facts to use in the D-N explanation? Arguably, string theory does not have principles or laws Option 2: Causal model of explanation No chance to see causation at work at this level Option 3: Mathematical explanations Option 4: Explanations based on uniﬁcation Option 5: Functional explanations from symmetry Ioan Muntean String Theory: Explanation and Fundamentalism
- 156. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionDoes string uniﬁcation entail string explanation? Some uniﬁcatory elements of string theory play explanatory roles Ioan Muntean String Theory: Explanation and Fundamentalism
- 157. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionDoes string uniﬁcation entail string explanation? Some uniﬁcatory elements of string theory play explanatory roles I argue here that string explanation is also independent of uniﬁcation Ioan Muntean String Theory: Explanation and Fundamentalism
- 158. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionDoes string uniﬁcation entail string explanation? Some uniﬁcatory elements of string theory play explanatory roles I argue here that string explanation is also independent of uniﬁcation The elements that do not unify but explain are constraints of the models Ioan Muntean String Theory: Explanation and Fundamentalism
- 159. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionCan constraints explain? String theory is a mathematical model of the dynamics of strings Ioan Muntean String Theory: Explanation and Fundamentalism
- 160. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionCan constraints explain? String theory is a mathematical model of the dynamics of strings Which elements play the explanatory role? Ioan Muntean String Theory: Explanation and Fundamentalism
- 161. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionCan constraints explain? String theory is a mathematical model of the dynamics of strings Which elements play the explanatory role? Ioan Muntean String Theory: Explanation and Fundamentalism
- 162. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionCan constraints explain? String theory is a mathematical model of the dynamics of strings Which elements play the explanatory role? Unlike other cases, I do not couple here uniﬁcation and explanation–not that strongly Ioan Muntean String Theory: Explanation and Fundamentalism
- 163. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionCan constraints explain? String theory is a mathematical model of the dynamics of strings Which elements play the explanatory role? Unlike other cases, I do not couple here uniﬁcation and explanation–not that strongly String explanation is independent of uniﬁcation Ioan Muntean String Theory: Explanation and Fundamentalism
- 164. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionCan constraints explain? String theory is a mathematical model of the dynamics of strings Which elements play the explanatory role? Unlike other cases, I do not couple here uniﬁcation and explanation–not that strongly String explanation is independent of uniﬁcation historically they came at diﬀerent moments Ioan Muntean String Theory: Explanation and Fundamentalism
- 165. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionCan constraints explain? String theory is a mathematical model of the dynamics of strings Which elements play the explanatory role? Unlike other cases, I do not couple here uniﬁcation and explanation–not that strongly String explanation is independent of uniﬁcation historically they came at diﬀerent moments Both physical and mathematical constraints explain Ioan Muntean String Theory: Explanation and Fundamentalism
- 166. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionCan constraints explain? String theory is a mathematical model of the dynamics of strings Which elements play the explanatory role? Unlike other cases, I do not couple here uniﬁcation and explanation–not that strongly String explanation is independent of uniﬁcation historically they came at diﬀerent moments Both physical and mathematical constraints explain Mathematical constraints Ioan Muntean String Theory: Explanation and Fundamentalism
- 167. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionCan constraints explain? String theory is a mathematical model of the dynamics of strings Which elements play the explanatory role? Unlike other cases, I do not couple here uniﬁcation and explanation–not that strongly String explanation is independent of uniﬁcation historically they came at diﬀerent moments Both physical and mathematical constraints explain Mathematical constraints String theory should render the probabilities of quantum events in the interval [0, 1] Ioan Muntean String Theory: Explanation and Fundamentalism
- 168. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory String Explanations Some case studies of string explanations Rejoinders and ConclusionCan constraints explain? String theory is a mathematical model of the dynamics of strings Which elements play the explanatory role? Unlike other cases, I do not couple here uniﬁcation and explanation–not that strongly String explanation is independent of uniﬁcation historically they came at diﬀerent moments Both physical and mathematical constraints explain Mathematical constraints String theory should render the probabilities of quantum events in the interval [0, 1] I place string explanation at the intersection of uniﬁcation and mathematical formalism. Ioan Muntean String Theory: Explanation and Fundamentalism
- 169. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQG: What is at stake? Ioan Muntean String Theory: Explanation and Fundamentalism
- 170. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQG: What is at stake? CONT: Spacetime is continuous Ioan Muntean String Theory: Explanation and Fundamentalism
- 171. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQG: What is at stake? CONT: Spacetime is continuous POINTS: Fundamental entities are pointlike particles Ioan Muntean String Theory: Explanation and Fundamentalism
- 172. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQG: What is at stake? CONT: Spacetime is continuous POINTS: Fundamental entities are pointlike particles BACKGROUND: Fundamental entities move in a ﬁxed background spacetime Ioan Muntean String Theory: Explanation and Fundamentalism
- 173. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesLoop quantum gravity Ioan Muntean String Theory: Explanation and Fundamentalism
- 174. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesLoop quantum gravity Denies: Ioan Muntean String Theory: Explanation and Fundamentalism
- 175. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesLoop quantum gravity Denies: BACKGROUND (in the letter and the spirit of GR), Ioan Muntean String Theory: Explanation and Fundamentalism
- 176. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesLoop quantum gravity Denies: BACKGROUND (in the letter and the spirit of GR), CONT (assumes discrete manifolds). Ioan Muntean String Theory: Explanation and Fundamentalism
- 177. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesLoop quantum gravity Denies: BACKGROUND (in the letter and the spirit of GR), CONT (assumes discrete manifolds). Assumes (tacitly): Ioan Muntean String Theory: Explanation and Fundamentalism
- 178. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesLoop quantum gravity Denies: BACKGROUND (in the letter and the spirit of GR), CONT (assumes discrete manifolds). Assumes (tacitly): POINTLIKE Ioan Muntean String Theory: Explanation and Fundamentalism
- 179. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesLoop quantum gravity Denies: BACKGROUND (in the letter and the spirit of GR), CONT (assumes discrete manifolds). Assumes (tacitly): POINTLIKE Loops are fundamental entities Ioan Muntean String Theory: Explanation and Fundamentalism
- 180. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesLoop quantum gravity Denies: BACKGROUND (in the letter and the spirit of GR), CONT (assumes discrete manifolds). Assumes (tacitly): POINTLIKE Loops are fundamental entities The relations among loops deﬁne spacetime (no BACKGROUND needed) Ioan Muntean String Theory: Explanation and Fundamentalism
- 181. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesLoop quantum gravity Denies: BACKGROUND (in the letter and the spirit of GR), CONT (assumes discrete manifolds). Assumes (tacitly): POINTLIKE Loops are fundamental entities The relations among loops deﬁne spacetime (no BACKGROUND needed) Geometry is discrete. Ioan Muntean String Theory: Explanation and Fundamentalism
- 182. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesLoop quantum gravity Denies: BACKGROUND (in the letter and the spirit of GR), CONT (assumes discrete manifolds). Assumes (tacitly): POINTLIKE Loops are fundamental entities The relations among loops deﬁne spacetime (no BACKGROUND needed) Geometry is discrete. See C. Rovelli, L. Smolin, A. Ashtekar etc. Ioan Muntean String Theory: Explanation and Fundamentalism
- 183. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString theory Ioan Muntean String Theory: Explanation and Fundamentalism
- 184. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString theory Keeps: Ioan Muntean String Theory: Explanation and Fundamentalism
- 185. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString theory Keeps: (provisionally. . . ) BACKGROUND Ioan Muntean String Theory: Explanation and Fundamentalism
- 186. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString theory Keeps: (provisionally. . . ) BACKGROUND tacitly CONT Ioan Muntean String Theory: Explanation and Fundamentalism
- 187. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString theory Keeps: (provisionally. . . ) BACKGROUND tacitly CONT Note: ways to combine NOT CONT with NOT POINTLIKE Ioan Muntean String Theory: Explanation and Fundamentalism
- 188. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString theory Keeps: (provisionally. . . ) BACKGROUND tacitly CONT Note: ways to combine NOT CONT with NOT POINTLIKE Denies (strongly): Ioan Muntean String Theory: Explanation and Fundamentalism
- 189. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString theory Keeps: (provisionally. . . ) BACKGROUND tacitly CONT Note: ways to combine NOT CONT with NOT POINTLIKE Denies (strongly): POINTLIKE Ioan Muntean String Theory: Explanation and Fundamentalism
- 190. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString theory Keeps: (provisionally. . . ) BACKGROUND tacitly CONT Note: ways to combine NOT CONT with NOT POINTLIKE Denies (strongly): POINTLIKE In other words, the fundamental nature of the world resembles more spaghetti/pasta than balls. Ioan Muntean String Theory: Explanation and Fundamentalism
- 191. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is advertised in QG? Explain the nature of space and time (esp. Loop QG) Ioan Muntean String Theory: Explanation and Fundamentalism
- 192. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is advertised in QG? Explain the nature of space and time (esp. Loop QG) Unify GR and QM (or QFT) (esp. string theory) Ioan Muntean String Theory: Explanation and Fundamentalism
- 193. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is advertised in QG? Explain the nature of space and time (esp. Loop QG) Unify GR and QM (or QFT) (esp. string theory) Quantize gravity Ioan Muntean String Theory: Explanation and Fundamentalism
- 194. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is advertised in QG? Explain the nature of space and time (esp. Loop QG) Unify GR and QM (or QFT) (esp. string theory) Quantize gravity Explain what happens at Planck scale (not achieved yet) Ioan Muntean String Theory: Explanation and Fundamentalism
- 195. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFour Assumptions Ioan Muntean String Theory: Explanation and Fundamentalism
- 196. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFour Assumptions (QG-UNIF) The uniﬁcation of all physical interactions, including gravity, is possible within one theory (the quantum gravity program). Ioan Muntean String Theory: Explanation and Fundamentalism
- 197. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFour Assumptions (QG-UNIF) The uniﬁcation of all physical interactions, including gravity, is possible within one theory (the quantum gravity program). (FUND) There is one fundamental entity in nature that can unify all known particles and interactions. Ioan Muntean String Theory: Explanation and Fundamentalism
- 198. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFour Assumptions (QG-UNIF) The uniﬁcation of all physical interactions, including gravity, is possible within one theory (the quantum gravity program). (FUND) There is one fundamental entity in nature that can unify all known particles and interactions. (SUSY) There is supersymmetry in nature. Ioan Muntean String Theory: Explanation and Fundamentalism
- 199. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFour Assumptions (QG-UNIF) The uniﬁcation of all physical interactions, including gravity, is possible within one theory (the quantum gravity program). (FUND) There is one fundamental entity in nature that can unify all known particles and interactions. (SUSY) There is supersymmetry in nature. (D>4) Physical spacetime may have a diﬀerent dimensionality and topology than the usual D=4 four-dimensional of the GR. Strings may live on subspaces of the physical spacetime and physical interactions may be conﬁned to some subspaces of the physical spacetime. Ioan Muntean String Theory: Explanation and Fundamentalism
- 200. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is denied in ST? Ioan Muntean String Theory: Explanation and Fundamentalism
- 201. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is denied in ST? Denies POINTLIKE: Reality can be described by a model in which the fundamental objects are point-like particles among which there are interactions. Ioan Muntean String Theory: Explanation and Fundamentalism
- 202. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is denied in ST? Denies POINTLIKE: Reality can be described by a model in which the fundamental objects are point-like particles among which there are interactions. Denies D=4: Point-like particles live in a spacetime with 4 (3+1) dimensions (three spatial dimensions and one temporal dimension) Ioan Muntean String Theory: Explanation and Fundamentalism
- 203. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is denied in ST? Denies POINTLIKE: Reality can be described by a model in which the fundamental objects are point-like particles among which there are interactions. Denies D=4: Point-like particles live in a spacetime with 4 (3+1) dimensions (three spatial dimensions and one temporal dimension) Denies SYM: The fundamental symmetries of the world are those instantiated by experiments in normal/standard conditions with elementary particles. Ioan Muntean String Theory: Explanation and Fundamentalism
- 204. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQG-UNIF Ioan Muntean String Theory: Explanation and Fundamentalism
- 205. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQG-UNIF The ideal of uniﬁcation has a good support in the history of physics ? Ioan Muntean String Theory: Explanation and Fundamentalism
- 206. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQG-UNIF The ideal of uniﬁcation has a good support in the history of physics ? We get in time more successful uniﬁcations than we get failed uniﬁcations. Ioan Muntean String Theory: Explanation and Fundamentalism
- 207. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQG-UNIF The ideal of uniﬁcation has a good support in the history of physics ? We get in time more successful uniﬁcations than we get failed uniﬁcations. optimistic meta-induction on uniﬁcation Ioan Muntean String Theory: Explanation and Fundamentalism
- 208. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQG-UNIF The ideal of uniﬁcation has a good support in the history of physics ? We get in time more successful uniﬁcations than we get failed uniﬁcations. optimistic meta-induction on uniﬁcation Critics admit in earnest the ST achieves uniﬁcation (??). Ioan Muntean String Theory: Explanation and Fundamentalism
- 209. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQG-UNIF The ideal of uniﬁcation has a good support in the history of physics ? We get in time more successful uniﬁcations than we get failed uniﬁcations. optimistic meta-induction on uniﬁcation Critics admit in earnest the ST achieves uniﬁcation (??). But do we really need it? Some other QG programs do not unify (Rovelli, Weinstein) Ioan Muntean String Theory: Explanation and Fundamentalism
- 210. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesUniﬁcation. The headlined feature of ST Ioan Muntean String Theory: Explanation and Fundamentalism
- 211. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesUniﬁcation. The headlined feature of ST Some mantras about string theory: Ioan Muntean String Theory: Explanation and Fundamentalism
- 212. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesUniﬁcation. The headlined feature of ST Some mantras about string theory: 1 General Relativity can be inferred from ST as a low limit energy: Ioan Muntean String Theory: Explanation and Fundamentalism
- 213. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesUniﬁcation. The headlined feature of ST Some mantras about string theory: 1 General Relativity can be inferred from ST as a low limit energy: 2 The Standard model, i.e. a Yang-Mills theory based on the group SU(3) ⊗ SU(2) ⊗ U(1) emerges from the theory. Ioan Muntean String Theory: Explanation and Fundamentalism
- 214. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesUniﬁcation. The headlined feature of ST Some mantras about string theory: 1 General Relativity can be inferred from ST as a low limit energy: 2 The Standard model, i.e. a Yang-Mills theory based on the group SU(3) ⊗ SU(2) ⊗ U(1) emerges from the theory. Dissenters admit this as a virtue. ?? Ioan Muntean String Theory: Explanation and Fundamentalism
- 215. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesUniﬁcation. The headlined feature of ST Some mantras about string theory: 1 General Relativity can be inferred from ST as a low limit energy: 2 The Standard model, i.e. a Yang-Mills theory based on the group SU(3) ⊗ SU(2) ⊗ U(1) emerges from the theory. Dissenters admit this as a virtue. ?? But at what price 1 and 2? Ioan Muntean String Theory: Explanation and Fundamentalism
- 216. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe serendipity of string theory “General relativity is arising within the framework of a consistent quantum theory. Ordinary QFT does not allow gravity to exist; string theory requires it.” (?, 4) “It is striking that Einstein’s equation turns up in what seems to be a rather out-of-the-way place, as the condition for Weyl invariance of a two dimensional ﬁeld theory. String Theory provides the physical connection between these two ideas.” ? Ioan Muntean String Theory: Explanation and Fundamentalism
- 217. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesYet another string uniﬁcation: dynamics and interaction Ioan Muntean String Theory: Explanation and Fundamentalism
- 218. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesYet another string uniﬁcation: dynamics and interaction QFT and the Standard Model have two set of laws for particles: Ioan Muntean String Theory: Explanation and Fundamentalism
- 219. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesYet another string uniﬁcation: dynamics and interaction QFT and the Standard Model have two set of laws for particles: Propagations Ioan Muntean String Theory: Explanation and Fundamentalism
- 220. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesYet another string uniﬁcation: dynamics and interaction QFT and the Standard Model have two set of laws for particles: Propagations Interactions Ioan Muntean String Theory: Explanation and Fundamentalism
- 221. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesYet another string uniﬁcation: dynamics and interaction QFT and the Standard Model have two set of laws for particles: Propagations Interactions In string theory, both propagation and interaction of particles are explained by one set of equations. Ioan Muntean String Theory: Explanation and Fundamentalism
- 222. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesYet another string uniﬁcation: dynamics and interaction QFT and the Standard Model have two set of laws for particles: Propagations Interactions In string theory, both propagation and interaction of particles are explained by one set of equations. This looks nice on paper, but in practice it involves super-symmetry. . . Ioan Muntean String Theory: Explanation and Fundamentalism
- 223. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesNo more inﬁnities No divergences in string theory because: Ioan Muntean String Theory: Explanation and Fundamentalism
- 224. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesNo more inﬁnities No divergences in string theory because: there is one type of world-sheet, the oriented Riemann surface Ioan Muntean String Theory: Explanation and Fundamentalism
- 225. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesNo more inﬁnities No divergences in string theory because: there is one type of world-sheet, the oriented Riemann surface has a unique world-sheet topology Ioan Muntean String Theory: Explanation and Fundamentalism
- 226. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesNo more inﬁnities No divergences in string theory because: there is one type of world-sheet, the oriented Riemann surface has a unique world-sheet topology the topology is UV ﬁnite, with one Feynman diagram Ioan Muntean String Theory: Explanation and Fundamentalism
- 227. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesNo more inﬁnities No divergences in string theory because: there is one type of world-sheet, the oriented Riemann surface has a unique world-sheet topology the topology is UV ﬁnite, with one Feynman diagram So it is in a better position than QFT Ioan Muntean String Theory: Explanation and Fundamentalism
- 228. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuper-symmetry Ioan Muntean String Theory: Explanation and Fundamentalism
- 229. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuper-symmetry String theory in its current formulation needs supersymmetry because Ioan Muntean String Theory: Explanation and Fundamentalism
- 230. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuper-symmetry String theory in its current formulation needs supersymmetry because A fermionic (and bosonic) ﬁeld on strings needs an extra ﬁeld, the super-symmetric ﬁeld (SUSY) Ioan Muntean String Theory: Explanation and Fundamentalism
- 231. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuper-symmetry String theory in its current formulation needs supersymmetry because A fermionic (and bosonic) ﬁeld on strings needs an extra ﬁeld, the super-symmetric ﬁeld (SUSY) Bosonic string theory does not need SUSY, but they are incomplete and inconsistent Ioan Muntean String Theory: Explanation and Fundamentalism
- 232. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuper-symmetry String theory in its current formulation needs supersymmetry because A fermionic (and bosonic) ﬁeld on strings needs an extra ﬁeld, the super-symmetric ﬁeld (SUSY) Bosonic string theory does not need SUSY, but they are incomplete and inconsistent To get the Yang-Mills ﬁelds and symmetries a very intricate topology of spacetime is needed Ioan Muntean String Theory: Explanation and Fundamentalism
- 233. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHistory: the humble and shady origins of string theory Ioan Muntean String Theory: Explanation and Fundamentalism
- 234. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHistory: the humble and shady origins of string theory Hard to deﬁne: there are several family of models in ST Ioan Muntean String Theory: Explanation and Fundamentalism
- 235. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHistory: the humble and shady origins of string theory Hard to deﬁne: there are several family of models in ST String theory underwent several plastic surgery procedures (“string revolutions”) Ioan Muntean String Theory: Explanation and Fundamentalism
- 236. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHistory: the humble and shady origins of string theory Hard to deﬁne: there are several family of models in ST String theory underwent several plastic surgery procedures (“string revolutions”) Has humble origins: Ioan Muntean String Theory: Explanation and Fundamentalism
- 237. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHistory: the humble and shady origins of string theory Hard to deﬁne: there are several family of models in ST String theory underwent several plastic surgery procedures (“string revolutions”) Has humble origins: Originated in the S-matrix formalism (of bygone days) Ioan Muntean String Theory: Explanation and Fundamentalism
- 238. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHistory: the humble and shady origins of string theory Hard to deﬁne: there are several family of models in ST String theory underwent several plastic surgery procedures (“string revolutions”) Has humble origins: Originated in the S-matrix formalism (of bygone days) ST was used to correct the hadron model Ioan Muntean String Theory: Explanation and Fundamentalism
- 239. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHistory: the humble and shady origins of string theory Hard to deﬁne: there are several family of models in ST String theory underwent several plastic surgery procedures (“string revolutions”) Has humble origins: Originated in the S-matrix formalism (of bygone days) ST was used to correct the hadron model It modeled the interaction of two quarks as being carried by a string. Ioan Muntean String Theory: Explanation and Fundamentalism
- 240. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHistory: the humble and shady origins of string theory Hard to deﬁne: there are several family of models in ST String theory underwent several plastic surgery procedures (“string revolutions”) Has humble origins: Originated in the S-matrix formalism (of bygone days) ST was used to correct the hadron model It modeled the interaction of two quarks as being carried by a string. The ends of the string were a quark and an antiquark Ioan Muntean String Theory: Explanation and Fundamentalism
- 241. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHistory: the humble and shady origins of string theory Hard to deﬁne: there are several family of models in ST String theory underwent several plastic surgery procedures (“string revolutions”) Has humble origins: Originated in the S-matrix formalism (of bygone days) ST was used to correct the hadron model It modeled the interaction of two quarks as being carried by a string. The ends of the string were a quark and an antiquark Three quarks can be composed to build a baryon. Ioan Muntean String Theory: Explanation and Fundamentalism
- 242. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHistory: the humble and shady origins of string theory Hard to deﬁne: there are several family of models in ST String theory underwent several plastic surgery procedures (“string revolutions”) Has humble origins: Originated in the S-matrix formalism (of bygone days) ST was used to correct the hadron model It modeled the interaction of two quarks as being carried by a string. The ends of the string were a quark and an antiquark Three quarks can be composed to build a baryon. But QCD completely ruled out the original string theory Ioan Muntean String Theory: Explanation and Fundamentalism
- 243. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST is a QFT program Ioan Muntean String Theory: Explanation and Fundamentalism
- 244. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST is a QFT program It does not solve the philosophical problems of QM or QFT Ioan Muntean String Theory: Explanation and Fundamentalism
- 245. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST is a QFT program It does not solve the philosophical problems of QM or QFT It gives up the principles of GR Ioan Muntean String Theory: Explanation and Fundamentalism
- 246. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST is a QFT program It does not solve the philosophical problems of QM or QFT It gives up the principles of GR It adds stringy problems on the top of the existing problems (Weingard) Ioan Muntean String Theory: Explanation and Fundamentalism
- 247. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST is a QFT program It does not solve the philosophical problems of QM or QFT It gives up the principles of GR It adds stringy problems on the top of the existing problems (Weingard) Are we really, really, really ready to give up relativity for short distances? Ioan Muntean String Theory: Explanation and Fundamentalism
- 248. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST is a QFT program It does not solve the philosophical problems of QM or QFT It gives up the principles of GR It adds stringy problems on the top of the existing problems (Weingard) Are we really, really, really ready to give up relativity for short distances? Some philosophers would be happy to entertain this possibility: Albert, Maudlin, i.a. Ioan Muntean String Theory: Explanation and Fundamentalism
- 249. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST is a QFT program It does not solve the philosophical problems of QM or QFT It gives up the principles of GR It adds stringy problems on the top of the existing problems (Weingard) Are we really, really, really ready to give up relativity for short distances? Some philosophers would be happy to entertain this possibility: Albert, Maudlin, i.a. Physicists are less enthusiastic Ioan Muntean String Theory: Explanation and Fundamentalism
- 250. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST is a QFT program It does not solve the philosophical problems of QM or QFT It gives up the principles of GR It adds stringy problems on the top of the existing problems (Weingard) Are we really, really, really ready to give up relativity for short distances? Some philosophers would be happy to entertain this possibility: Albert, Maudlin, i.a. Physicists are less enthusiastic This is sometimes advertised as a virtue of ST. Ioan Muntean String Theory: Explanation and Fundamentalism
- 251. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST is a QFT program It does not solve the philosophical problems of QM or QFT It gives up the principles of GR It adds stringy problems on the top of the existing problems (Weingard) Are we really, really, really ready to give up relativity for short distances? Some philosophers would be happy to entertain this possibility: Albert, Maudlin, i.a. Physicists are less enthusiastic This is sometimes advertised as a virtue of ST. Ioan Muntean String Theory: Explanation and Fundamentalism
- 252. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesIs ST a speciﬁc QG? Ioan Muntean String Theory: Explanation and Fundamentalism
- 253. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesIs ST a speciﬁc QG? All other QG programs integrate general relativity with quantum mechanics simpliciter Ioan Muntean String Theory: Explanation and Fundamentalism
- 254. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesIs ST a speciﬁc QG? All other QG programs integrate general relativity with quantum mechanics simpliciter String theory is a grand uniﬁcation model: GR raise from a QFT formalism (a Standard Model formalism) Ioan Muntean String Theory: Explanation and Fundamentalism
- 255. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesIs ST a speciﬁc QG? All other QG programs integrate general relativity with quantum mechanics simpliciter String theory is a grand uniﬁcation model: GR raise from a QFT formalism (a Standard Model formalism) Other QG integrate QM into GR Ioan Muntean String Theory: Explanation and Fundamentalism
- 256. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesIs ST a speciﬁc QG? All other QG programs integrate general relativity with quantum mechanics simpliciter String theory is a grand uniﬁcation model: GR raise from a QFT formalism (a Standard Model formalism) Other QG integrate QM into GR Hence ST is not strictly speaking a QG program because it is centred on the Standard Model, on QFT in fact (Rickles, 2010) Ioan Muntean String Theory: Explanation and Fundamentalism
- 257. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhy “super” is not good Ioan Muntean String Theory: Explanation and Fundamentalism
- 258. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhy “super” is not good There is Super-Symmetry in the Standard Model (SSSM): most likely, false Ioan Muntean String Theory: Explanation and Fundamentalism
- 259. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhy “super” is not good There is Super-Symmetry in the Standard Model (SSSM): most likely, false Super-gravity (SUGRAV): most likely false Ioan Muntean String Theory: Explanation and Fundamentalism
- 260. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhy “super” is not good There is Super-Symmetry in the Standard Model (SSSM): most likely, false Super-gravity (SUGRAV): most likely false Superstring theory uses SUSY in a diﬀerent manner. Not as a conjunction of SSM and SUGRAV Ioan Muntean String Theory: Explanation and Fundamentalism
- 261. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhy “super” is not good There is Super-Symmetry in the Standard Model (SSSM): most likely, false Super-gravity (SUGRAV): most likely false Superstring theory uses SUSY in a diﬀerent manner. Not as a conjunction of SSM and SUGRAV it employs the mathematical apparatus of them Ioan Muntean String Theory: Explanation and Fundamentalism
- 262. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhy “super” is not good There is Super-Symmetry in the Standard Model (SSSM): most likely, false Super-gravity (SUGRAV): most likely false Superstring theory uses SUSY in a diﬀerent manner. Not as a conjunction of SSM and SUGRAV it employs the mathematical apparatus of them Philosophical question: can we combine/unify two false models into a model closer to truth than the uniﬁed models? Ioan Muntean String Theory: Explanation and Fundamentalism
- 263. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuperstring Theory Ioan Muntean String Theory: Explanation and Fundamentalism
- 264. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuperstring Theory Green and Schwarz (1984) Ioan Muntean String Theory: Explanation and Fundamentalism
- 265. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuperstring Theory Green and Schwarz (1984) No tachyons Ioan Muntean String Theory: Explanation and Fundamentalism
- 266. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuperstring Theory Green and Schwarz (1984) No tachyons Finite and consistent Ioan Muntean String Theory: Explanation and Fundamentalism
- 267. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuperstring Theory Green and Schwarz (1984) No tachyons Finite and consistent Symmetry group: SO(32) Ioan Muntean String Theory: Explanation and Fundamentalism
- 268. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSuperstring Theory Green and Schwarz (1984) No tachyons Finite and consistent Symmetry group: SO(32) D=10 Ioan Muntean String Theory: Explanation and Fundamentalism
- 269. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFive types of string theories Ioan Muntean String Theory: Explanation and Fundamentalism
- 270. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFive types of string theories Bosonic string theory: D=26, with no symmetry, in which strings vibrate only in the bosonic mode. Ioan Muntean String Theory: Explanation and Fundamentalism
- 271. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFive types of string theories Bosonic string theory: D=26, with no symmetry, in which strings vibrate only in the bosonic mode. Type I String Theory: fermions and bosons: D=10 and supersymmetry is present. Ioan Muntean String Theory: Explanation and Fundamentalism
- 272. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFive types of string theories Bosonic string theory: D=26, with no symmetry, in which strings vibrate only in the bosonic mode. Type I String Theory: fermions and bosons: D=10 and supersymmetry is present. Type II-A: Supersymmetry is present and strings are open and closed. D-branes are also subspaces on which strings are attached. Fermions are not chiral. Ioan Muntean String Theory: Explanation and Fundamentalism
- 273. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFive types of string theories Bosonic string theory: D=26, with no symmetry, in which strings vibrate only in the bosonic mode. Type I String Theory: fermions and bosons: D=10 and supersymmetry is present. Type II-A: Supersymmetry is present and strings are open and closed. D-branes are also subspaces on which strings are attached. Fermions are not chiral. Type II-B: same as Type II-A, but includes chirality. Ioan Muntean String Theory: Explanation and Fundamentalism
- 274. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFive types of string theories Bosonic string theory: D=26, with no symmetry, in which strings vibrate only in the bosonic mode. Type I String Theory: fermions and bosons: D=10 and supersymmetry is present. Type II-A: Supersymmetry is present and strings are open and closed. D-branes are also subspaces on which strings are attached. Fermions are not chiral. Type II-B: same as Type II-A, but includes chirality. Heterotic ST: Only closed strings. D=10 on left movers, and D=26 on right movers Ioan Muntean String Theory: Explanation and Fundamentalism
- 275. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesFive types of string theories Bosonic string theory: D=26, with no symmetry, in which strings vibrate only in the bosonic mode. Type I String Theory: fermions and bosons: D=10 and supersymmetry is present. Type II-A: Supersymmetry is present and strings are open and closed. D-branes are also subspaces on which strings are attached. Fermions are not chiral. Type II-B: same as Type II-A, but includes chirality. Heterotic ST: Only closed strings. D=10 on left movers, and D=26 on right movers Several types of heterotic string theories exist Ioan Muntean String Theory: Explanation and Fundamentalism
- 276. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString Theory and spacetime Ioan Muntean String Theory: Explanation and Fundamentalism
- 277. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString Theory and spacetime Unlike other QG programs, string theory’s structure of spacetime is more complicated: Ioan Muntean String Theory: Explanation and Fundamentalism
- 278. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString Theory and spacetime Unlike other QG programs, string theory’s structure of spacetime is more complicated: Dimensionality D>4 Ioan Muntean String Theory: Explanation and Fundamentalism
- 279. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString Theory and spacetime Unlike other QG programs, string theory’s structure of spacetime is more complicated: Dimensionality D>4 Exotic topologies Ioan Muntean String Theory: Explanation and Fundamentalism
- 280. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString Theory and spacetime Unlike other QG programs, string theory’s structure of spacetime is more complicated: Dimensionality D>4 Exotic topologies Compactiﬁcation Ioan Muntean String Theory: Explanation and Fundamentalism
- 281. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString Theory and spacetime Unlike other QG programs, string theory’s structure of spacetime is more complicated: Dimensionality D>4 Exotic topologies Compactiﬁcation The dynamics of spacetime is codiﬁed by the “dilaton” ﬁeld Ioan Muntean String Theory: Explanation and Fundamentalism
- 282. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString Theory and spacetime Unlike other QG programs, string theory’s structure of spacetime is more complicated: Dimensionality D>4 Exotic topologies Compactiﬁcation The dynamics of spacetime is codiﬁed by the “dilaton” ﬁeld The GR physicists would insist: Ioan Muntean String Theory: Explanation and Fundamentalism
- 283. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesString Theory and spacetime Unlike other QG programs, string theory’s structure of spacetime is more complicated: Dimensionality D>4 Exotic topologies Compactiﬁcation The dynamics of spacetime is codiﬁed by the “dilaton” ﬁeld The GR physicists would insist: So what? What determines the structure of the convoluted spacetime? Ioan Muntean String Theory: Explanation and Fundamentalism
- 284. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBACKGROUND in ST Ioan Muntean String Theory: Explanation and Fundamentalism
- 285. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBACKGROUND in ST There is a way to answer BACKGROUND: Ioan Muntean String Theory: Explanation and Fundamentalism
- 286. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBACKGROUND in ST There is a way to answer BACKGROUND: ST can be formulated in curved spacetime ((?, ch. 3)) Ioan Muntean String Theory: Explanation and Fundamentalism
- 287. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBACKGROUND in ST There is a way to answer BACKGROUND: ST can be formulated in curved spacetime ((?, ch. 3)) So replace η with G Ioan Muntean String Theory: Explanation and Fundamentalism
- 288. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBACKGROUND in ST There is a way to answer BACKGROUND: ST can be formulated in curved spacetime ((?, ch. 3)) So replace η with G Here we have a perturbation theory Ioan Muntean String Theory: Explanation and Fundamentalism
- 289. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBACKGROUND in ST There is a way to answer BACKGROUND: ST can be formulated in curved spacetime ((?, ch. 3)) So replace η with G Here we have a perturbation theory Here we go again! Ioan Muntean String Theory: Explanation and Fundamentalism
- 290. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe naive solution to BACKGROUND Ioan Muntean String Theory: Explanation and Fundamentalism
- 291. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe naive solution to BACKGROUND Curved spacetime is a formed by a collection of gravitons Ioan Muntean String Theory: Explanation and Fundamentalism
- 292. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe naive solution to BACKGROUND Curved spacetime is a formed by a collection of gravitons Gravitons are states of strings Ioan Muntean String Theory: Explanation and Fundamentalism
- 293. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe naive solution to BACKGROUND Curved spacetime is a formed by a collection of gravitons Gravitons are states of strings So the background spacetime is in itself dynamical. Ioan Muntean String Theory: Explanation and Fundamentalism
- 294. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe naive solution to BACKGROUND Curved spacetime is a formed by a collection of gravitons Gravitons are states of strings So the background spacetime is in itself dynamical. Do string theorists beg the question? Ioan Muntean String Theory: Explanation and Fundamentalism
- 295. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBackground spacetime as a interaction among strings Ioan Muntean String Theory: Explanation and Fundamentalism
- 296. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBackground spacetime as a interaction among strings Diﬀerent G, B and Φ ﬁelds give diﬀerent backgrounds Ioan Muntean String Theory: Explanation and Fundamentalism
- 297. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBackground spacetime as a interaction among strings Diﬀerent G, B and Φ ﬁelds give diﬀerent backgrounds But Φ0 = λ is the coupling constant among strings. Ioan Muntean String Theory: Explanation and Fundamentalism
- 298. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBackground spacetime as a interaction among strings Diﬀerent G, B and Φ ﬁelds give diﬀerent backgrounds But Φ0 = λ is the coupling constant among strings. The coupling constant is determined by the dynamics. Ioan Muntean String Theory: Explanation and Fundamentalism
- 299. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBackground spacetime as a interaction among strings Diﬀerent G, B and Φ ﬁelds give diﬀerent backgrounds But Φ0 = λ is the coupling constant among strings. The coupling constant is determined by the dynamics. In ST ﬁelds can propagate only in speciﬁc background spacetimes, strongly constrained. Ioan Muntean String Theory: Explanation and Fundamentalism
- 300. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST and Lorentz invariance Ioan Muntean String Theory: Explanation and Fundamentalism
- 301. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST and Lorentz invariance “The basic physical consistency conditions are few in number. We require Lorentz invariance, and we require that quantum mechanical probabilities be positive and conserved—to date, nothing in string theory seems to require that the standard quantum mechanical framework be modiﬁed, though it would be interesting to learn otherwise” (Polchinski 1998, 1:116). Ioan Muntean String Theory: Explanation and Fundamentalism
- 302. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST as a conservative program Ioan Muntean String Theory: Explanation and Fundamentalism
- 303. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST as a conservative program Tasks for a bosonic ST Ioan Muntean String Theory: Explanation and Fundamentalism
- 304. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST as a conservative program Tasks for a bosonic ST Quantize a classical entity, the string Ioan Muntean String Theory: Explanation and Fundamentalism
- 305. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST as a conservative program Tasks for a bosonic ST Quantize a classical entity, the string Try to recover Lorentz invariance Ioan Muntean String Theory: Explanation and Fundamentalism
- 306. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST as a conservative program Tasks for a bosonic ST Quantize a classical entity, the string Try to recover Lorentz invariance Eliminate tachyonic modes and ghost ﬁelds Ioan Muntean String Theory: Explanation and Fundamentalism
- 307. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST as a conservative program Tasks for a bosonic ST Quantize a classical entity, the string Try to recover Lorentz invariance Eliminate tachyonic modes and ghost ﬁelds Problems: Ioan Muntean String Theory: Explanation and Fundamentalism
- 308. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST as a conservative program Tasks for a bosonic ST Quantize a classical entity, the string Try to recover Lorentz invariance Eliminate tachyonic modes and ghost ﬁelds Problems: Assumes a classical concept of spacetime manifold, as does QFT Ioan Muntean String Theory: Explanation and Fundamentalism
- 309. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST as a conservative program Tasks for a bosonic ST Quantize a classical entity, the string Try to recover Lorentz invariance Eliminate tachyonic modes and ghost ﬁelds Problems: Assumes a classical concept of spacetime manifold, as does QFT It has various techniques of quantization (conformal, BRST, ligh-cone) each ascertaining to diﬀerent results Ioan Muntean String Theory: Explanation and Fundamentalism
- 310. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST as a conservative program Tasks for a bosonic ST Quantize a classical entity, the string Try to recover Lorentz invariance Eliminate tachyonic modes and ghost ﬁelds Problems: Assumes a classical concept of spacetime manifold, as does QFT It has various techniques of quantization (conformal, BRST, ligh-cone) each ascertaining to diﬀerent results piggybacks on classical mechanics and special relativity Ioan Muntean String Theory: Explanation and Fundamentalism
- 311. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesST as a conservative program Tasks for a bosonic ST Quantize a classical entity, the string Try to recover Lorentz invariance Eliminate tachyonic modes and ghost ﬁelds Problems: Assumes a classical concept of spacetime manifold, as does QFT It has various techniques of quantization (conformal, BRST, ligh-cone) each ascertaining to diﬀerent results piggybacks on classical mechanics and special relativity Is it a good candidate for a TOE or a fundamental theory if it bypasses GR? Ioan Muntean String Theory: Explanation and Fundamentalism
- 312. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model Ioan Muntean String Theory: Explanation and Fundamentalism
- 313. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model Take a string (open or closed) Ioan Muntean String Theory: Explanation and Fundamentalism
- 314. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model Take a string (open or closed) Write down its action (roughly, it is the area of the string worldsheet) Ioan Muntean String Theory: Explanation and Fundamentalism
- 315. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model Take a string (open or closed) Write down its action (roughly, it is the area of the string worldsheet) Nambu Goto SNG Ioan Muntean String Theory: Explanation and Fundamentalism
- 316. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model Take a string (open or closed) Write down its action (roughly, it is the area of the string worldsheet) Nambu Goto SNG Polyakov: T √ SNB−σ = SP = − d2 σ −hhαβ ∂α X µ ∂ α X ν 2 Ioan Muntean String Theory: Explanation and Fundamentalism
- 317. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model Take a string (open or closed) Write down its action (roughly, it is the area of the string worldsheet) Nambu Goto SNG Polyakov: T √ SNB−σ = SP = − d2 σ −hhαβ ∂α X µ ∂ α X ν 2 Look at the symmetries of the action Ioan Muntean String Theory: Explanation and Fundamentalism
- 318. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model Take a string (open or closed) Write down its action (roughly, it is the area of the string worldsheet) Nambu Goto SNG Polyakov: T √ SNB−σ = SP = − d2 σ −hhαβ ∂α X µ ∂ α X ν 2 Look at the symmetries of the action Poincare group: Lorentz and translations (global) Ioan Muntean String Theory: Explanation and Fundamentalism
- 319. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model Take a string (open or closed) Write down its action (roughly, it is the area of the string worldsheet) Nambu Goto SNG Polyakov: T √ SNB−σ = SP = − d2 σ −hhαβ ∂α X µ ∂ α X ν 2 Look at the symmetries of the action Poincare group: Lorentz and translations (global) Reparametrization group (local) Ioan Muntean String Theory: Explanation and Fundamentalism
- 320. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model Take a string (open or closed) Write down its action (roughly, it is the area of the string worldsheet) Nambu Goto SNG Polyakov: T √ SNB−σ = SP = − d2 σ −hhαβ ∂α X µ ∂ α X ν 2 Look at the symmetries of the action Poincare group: Lorentz and translations (global) Reparametrization group (local) Weyl scaling (local) Ioan Muntean String Theory: Explanation and Fundamentalism
- 321. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model Take a string (open or closed) Write down its action (roughly, it is the area of the string worldsheet) Nambu Goto SNG Polyakov: T √ SNB−σ = SP = − d2 σ −hhαβ ∂α X µ ∂ α X ν 2 Look at the symmetries of the action Poincare group: Lorentz and translations (global) Reparametrization group (local) Weyl scaling (local) Let it vibrate in a (ﬂat?) spacetime with D dimensions Ioan Muntean String Theory: Explanation and Fundamentalism
- 322. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model quantized Ioan Muntean String Theory: Explanation and Fundamentalism
- 323. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model quantized Quantize the string action (ﬁrst quantization): Ioan Muntean String Theory: Explanation and Fundamentalism
- 324. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model quantized Quantize the string action (ﬁrst quantization): Several procedures are available: Ioan Muntean String Theory: Explanation and Fundamentalism
- 325. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model quantized Quantize the string action (ﬁrst quantization): Several procedures are available: Covariant Ioan Muntean String Theory: Explanation and Fundamentalism
- 326. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model quantized Quantize the string action (ﬁrst quantization): Several procedures are available: Covariant BRST Ioan Muntean String Theory: Explanation and Fundamentalism
- 327. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model quantized Quantize the string action (ﬁrst quantization): Several procedures are available: Covariant BRST Light cone Ioan Muntean String Theory: Explanation and Fundamentalism
- 328. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model quantized Quantize the string action (ﬁrst quantization): Several procedures are available: Covariant BRST Light cone Impose canonical commutation relations Ioan Muntean String Theory: Explanation and Fundamentalism
- 329. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe toy model quantized Quantize the string action (ﬁrst quantization): Several procedures are available: Covariant BRST Light cone Impose canonical commutation relations Look at its spectrum and what it contains Ioan Muntean String Theory: Explanation and Fundamentalism
- 330. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe closed string spectrum Ioan Muntean String Theory: Explanation and Fundamentalism
- 331. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe closed string spectrum αµ −ik(τ +σ) 2 X µ (τ, σ) = xµ µ L 2 + 2 p (τ + σ) + i 2 S √S k e k k=0 µ xµ 2 αµ −ik(τ −σ) ¯k XR (τ, σ) = 2 + S 2 p µ (τ ¯ − σ) + i √S2 k e k=0 Ioan Muntean String Theory: Explanation and Fundamentalism
- 332. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model Ioan Muntean String Theory: Explanation and Fundamentalism
- 333. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. Ioan Muntean String Theory: Explanation and Fundamentalism
- 334. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: Ioan Muntean String Theory: Explanation and Fundamentalism
- 335. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: 1 Tachyonic states, because of the 1 M2 |0 = − |0 α Ioan Muntean String Theory: Explanation and Fundamentalism
- 336. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: 1 Tachyonic states, because of the 1 M2 |0 = − |0 α 2 Spin-2 bosonic states Ioan Muntean String Theory: Explanation and Fundamentalism
- 337. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: 1 Tachyonic states, because of the 1 M2 |0 = − |0 α 2 Spin-2 bosonic states 3 Negative norm states Ioan Muntean String Theory: Explanation and Fundamentalism
- 338. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: 1 Tachyonic states, because of the 1 M2 |0 = − |0 α 2 Spin-2 bosonic states 3 Negative norm states Which of them needs to stay, which goes? Ioan Muntean String Theory: Explanation and Fundamentalism
- 339. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: 1 Tachyonic states, because of the 1 M2 |0 = − |0 α 2 Spin-2 bosonic states 3 Negative norm states Which of them needs to stay, which goes? It depends: Ioan Muntean String Theory: Explanation and Fundamentalism
- 340. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: 1 Tachyonic states, because of the 1 M2 |0 = − |0 α 2 Spin-2 bosonic states 3 Negative norm states Which of them needs to stay, which goes? It depends: If string theory is a model of hadrons, all need to go. Ioan Muntean String Theory: Explanation and Fundamentalism
- 341. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: 1 Tachyonic states, because of the 1 M2 |0 = − |0 α 2 Spin-2 bosonic states 3 Negative norm states Which of them needs to stay, which goes? It depends: If string theory is a model of hadrons, all need to go. And that was not possible. Ioan Muntean String Theory: Explanation and Fundamentalism
- 342. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: 1 Tachyonic states, because of the 1 M2 |0 = − |0 α 2 Spin-2 bosonic states 3 Negative norm states Which of them needs to stay, which goes? It depends: If string theory is a model of hadrons, all need to go. And that was not possible. 3. can be stripped out. Ioan Muntean String Theory: Explanation and Fundamentalism
- 343. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: 1 Tachyonic states, because of the 1 M2 |0 = − |0 α 2 Spin-2 bosonic states 3 Negative norm states Which of them needs to stay, which goes? It depends: If string theory is a model of hadrons, all need to go. And that was not possible. 3. can be stripped out. 1. cannot be eliminated and Ioan Muntean String Theory: Explanation and Fundamentalism
- 344. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSome constraints on the toy model The spectra (for both open and closed strings) look “ugly”. It has: 1 Tachyonic states, because of the 1 M2 |0 = − |0 α 2 Spin-2 bosonic states 3 Negative norm states Which of them needs to stay, which goes? It depends: If string theory is a model of hadrons, all need to go. And that was not possible. 3. can be stripped out. 1. cannot be eliminated and 2. is a real surprise, itMuntean signature of gravitation Ioan is the String Theory: Explanation and Fundamentalism
- 345. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirasoro operators Ioan Muntean String Theory: Explanation and Fundamentalism
- 346. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirasoro operators They are used to eliminate negative norm states Ioan Muntean String Theory: Explanation and Fundamentalism
- 347. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirasoro operators They are used to eliminate negative norm states Open : D [Lm , Ln ] = (m − n) Ln+n + 12 m3 − m δm+n,0 Closed : D [Lm , Ln ] = (m − n) Ln+n + 12 m3 − m δm+n,0 ¯ ¯ ¯ D Lm , Ln = (m − n) Ln+n + 12 m3 − m δm+n,0 Ioan Muntean String Theory: Explanation and Fundamentalism
- 348. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirasoro operators They are used to eliminate negative norm states Open : D [Lm , Ln ] = (m − n) Ln+n + 12 m3 − m δm+n,0 Closed : D [Lm , Ln ] = (m − n) Ln+n + 12 m3 − m δm+n,0 ¯ ¯ ¯ D Lm , Ln = (m − n) Ln+n + 12 m3 − m δm+n,0 I follow here the notation in: ? Ioan Muntean String Theory: Explanation and Fundamentalism
- 349. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirasoro operators They are used to eliminate negative norm states Open : D [Lm , Ln ] = (m − n) Ln+n + 12 m3 − m δm+n,0 Closed : D [Lm , Ln ] = (m − n) Ln+n + 12 m3 − m δm+n,0 ¯ ¯ ¯ D Lm , Ln = (m − n) Ln+n + 12 m3 − m δm+n,0 I follow here the notation in: ? by working on the expectation values of the Virasoro operators, one can infer: Ioan Muntean String Theory: Explanation and Fundamentalism
- 350. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirasoro operators They are used to eliminate negative norm states Open : D [Lm , Ln ] = (m − n) Ln+n + 12 m3 − m δm+n,0 Closed : D [Lm , Ln ] = (m − n) Ln+n + 12 m3 − m δm+n,0 ¯ ¯ ¯ D Lm , Ln = (m − n) Ln+n + 12 m3 − m δm+n,0 I follow here the notation in: ? by working on the expectation values of the Virasoro operators, one can infer: First condition of “physicality”: No ghost ﬁelds (with negative norm states) Ioan Muntean String Theory: Explanation and Fundamentalism
- 351. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirasoro operators They are used to eliminate negative norm states Open : D [Lm , Ln ] = (m − n) Ln+n + 12 m3 − m δm+n,0 Closed : D [Lm , Ln ] = (m − n) Ln+n + 12 m3 − m δm+n,0 ¯ ¯ ¯ D Lm , Ln = (m − n) Ln+n + 12 m3 − m δm+n,0 I follow here the notation in: ? by working on the expectation values of the Virasoro operators, one can infer: First condition of “physicality”: No ghost ﬁelds (with negative norm states) Applied to the bosonic ST, this renders: D=26, a=1 Ioan Muntean String Theory: Explanation and Fundamentalism
- 352. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirtues and vices Ioan Muntean String Theory: Explanation and Fundamentalism
- 353. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirtues and vices The original bosonic ST has: Ioan Muntean String Theory: Explanation and Fundamentalism
- 354. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirtues and vices The original bosonic ST has: 1 Ghost states Ioan Muntean String Theory: Explanation and Fundamentalism
- 355. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirtues and vices The original bosonic ST has: 1 Ghost states 2 Tachyonic modes Ioan Muntean String Theory: Explanation and Fundamentalism
- 356. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirtues and vices The original bosonic ST has: 1 Ghost states 2 Tachyonic modes 3 A massless spin-2 particle Ioan Muntean String Theory: Explanation and Fundamentalism
- 357. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirtues and vices The original bosonic ST has: 1 Ghost states 2 Tachyonic modes 3 A massless spin-2 particle Originally, 3. was a vice of the theory, then it became a virtue (identiﬁed with the graviton). Ioan Muntean String Theory: Explanation and Fundamentalism
- 358. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirtues and vices The original bosonic ST has: 1 Ghost states 2 Tachyonic modes 3 A massless spin-2 particle Originally, 3. was a vice of the theory, then it became a virtue (identiﬁed with the graviton). In bosonic string theory, there is no way to eliminate 2. Ioan Muntean String Theory: Explanation and Fundamentalism
- 359. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirtues and vices The original bosonic ST has: 1 Ghost states 2 Tachyonic modes 3 A massless spin-2 particle Originally, 3. was a vice of the theory, then it became a virtue (identiﬁed with the graviton). In bosonic string theory, there is no way to eliminate 2. There are several constraints and symmetries that can eliminate 1. but that entails: Ioan Muntean String Theory: Explanation and Fundamentalism
- 360. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirtues and vices The original bosonic ST has: 1 Ghost states 2 Tachyonic modes 3 A massless spin-2 particle Originally, 3. was a vice of the theory, then it became a virtue (identiﬁed with the graviton). In bosonic string theory, there is no way to eliminate 2. There are several constraints and symmetries that can eliminate 1. but that entails: D=26 Ioan Muntean String Theory: Explanation and Fundamentalism
- 361. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesVirtues and vices The original bosonic ST has: 1 Ghost states 2 Tachyonic modes 3 A massless spin-2 particle Originally, 3. was a vice of the theory, then it became a virtue (identiﬁed with the graviton). In bosonic string theory, there is no way to eliminate 2. There are several constraints and symmetries that can eliminate 1. but that entails: D=26 Can’t get rid of 2. and 3. Ioan Muntean String Theory: Explanation and Fundamentalism
- 362. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is X (σ, τ )? Ioan Muntean String Theory: Explanation and Fundamentalism
- 363. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is X (σ, τ )? Here is where ST is open to interpretations. Ioan Muntean String Theory: Explanation and Fundamentalism
- 364. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is X (σ, τ )? Here is where ST is open to interpretations. Two interpretations Ioan Muntean String Theory: Explanation and Fundamentalism
- 365. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is X (σ, τ )? Here is where ST is open to interpretations. Two interpretations the GR “friendly” interpretation: X a system of coordinates Ioan Muntean String Theory: Explanation and Fundamentalism
- 366. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesWhat is X (σ, τ )? Here is where ST is open to interpretations. Two interpretations the GR “friendly” interpretation: X a system of coordinates GR “unfriendly” interpretation, inspired by QFT: X is a bosonic ﬁeld on the worldsheet Ioan Muntean String Theory: Explanation and Fundamentalism
- 367. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model Ioan Muntean String Theory: Explanation and Fundamentalism
- 368. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model what is needed to eliminate tachyons and explain more than the graviton? Ioan Muntean String Theory: Explanation and Fundamentalism
- 369. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model what is needed to eliminate tachyons and explain more than the graviton? Supersymetry (SUSY), inter alia Ioan Muntean String Theory: Explanation and Fundamentalism
- 370. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model what is needed to eliminate tachyons and explain more than the graviton? Supersymetry (SUSY), inter alia What is SUSY in string theory? Ioan Muntean String Theory: Explanation and Fundamentalism
- 371. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model what is needed to eliminate tachyons and explain more than the graviton? Supersymetry (SUSY), inter alia What is SUSY in string theory? Mainly, it is an extra ﬁeld that can be put: Ioan Muntean String Theory: Explanation and Fundamentalism
- 372. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model what is needed to eliminate tachyons and explain more than the graviton? Supersymetry (SUSY), inter alia What is SUSY in string theory? Mainly, it is an extra ﬁeld that can be put: On the worldsheet (Ramond-Neveu-Schwarz model, RNS) Ioan Muntean String Theory: Explanation and Fundamentalism
- 373. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model what is needed to eliminate tachyons and explain more than the graviton? Supersymetry (SUSY), inter alia What is SUSY in string theory? Mainly, it is an extra ﬁeld that can be put: On the worldsheet (Ramond-Neveu-Schwarz model, RNS) On the real spacetime (Green-Schwarz model, GS) Ioan Muntean String Theory: Explanation and Fundamentalism
- 374. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model what is needed to eliminate tachyons and explain more than the graviton? Supersymetry (SUSY), inter alia What is SUSY in string theory? Mainly, it is an extra ﬁeld that can be put: On the worldsheet (Ramond-Neveu-Schwarz model, RNS) On the real spacetime (Green-Schwarz model, GS) RNS adds a new term to the SP action Ioan Muntean String Theory: Explanation and Fundamentalism
- 375. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model what is needed to eliminate tachyons and explain more than the graviton? Supersymetry (SUSY), inter alia What is SUSY in string theory? Mainly, it is an extra ﬁeld that can be put: On the worldsheet (Ramond-Neveu-Schwarz model, RNS) On the real spacetime (Green-Schwarz model, GS) RNS adds a new term to the SP action The new term is a Majorana spinor Ψ with two components Ψ− Ψ+ Ioan Muntean String Theory: Explanation and Fundamentalism
- 376. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model what is needed to eliminate tachyons and explain more than the graviton? Supersymetry (SUSY), inter alia What is SUSY in string theory? Mainly, it is an extra ﬁeld that can be put: On the worldsheet (Ramond-Neveu-Schwarz model, RNS) On the real spacetime (Green-Schwarz model, GS) RNS adds a new term to the SP action The new term is a Majorana spinor Ψ with two components Ψ− Ψ+ It is fermionic in nature Ioan Muntean String Theory: Explanation and Fundamentalism
- 377. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY on the world-sheet: the RNS model what is needed to eliminate tachyons and explain more than the graviton? Supersymetry (SUSY), inter alia What is SUSY in string theory? Mainly, it is an extra ﬁeld that can be put: On the worldsheet (Ramond-Neveu-Schwarz model, RNS) On the real spacetime (Green-Schwarz model, GS) RNS adds a new term to the SP action The new term is a Majorana spinor Ψ with two components Ψ− Ψ+ It is fermionic in nature The bosonic ﬁeld X (σ, τ ) stays, too. Ioan Muntean String Theory: Explanation and Fundamentalism
- 378. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe SUSY transformation Ioan Muntean String Theory: Explanation and Fundamentalism
- 379. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe SUSY transformation With SUSY we need the new transformation . Ioan Muntean String Theory: Explanation and Fundamentalism
- 380. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe SUSY transformation With SUSY we need the new transformation . It is a Majorana spinor, too. Ioan Muntean String Theory: Explanation and Fundamentalism
- 381. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe SUSY transformation With SUSY we need the new transformation . It is a Majorana spinor, too. The two transformations are now supersymmetric: Ioan Muntean String Theory: Explanation and Fundamentalism
- 382. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesThe SUSY transformation With SUSY we need the new transformation . It is a Majorana spinor, too. The two transformations are now supersymmetric: δXµ = ¯Ψµ δΨµ = −iρα ∂α Xµ Ioan Muntean String Theory: Explanation and Fundamentalism
- 383. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBoundary conditions of the open string Ioan Muntean String Theory: Explanation and Fundamentalism
- 384. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBoundary conditions of the open string Two movers (similar to progressive and regressive waves): left movers Ψµ , right movers Ψµ . + − Ioan Muntean String Theory: Explanation and Fundamentalism
- 385. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBoundary conditions of the open string Two movers (similar to progressive and regressive waves): left movers Ψµ , right movers Ψµ . + − at σ = 0 we take: Ψ+ (0, τ ) = Ψ− (0, τ ) µ µ Ioan Muntean String Theory: Explanation and Fundamentalism
- 386. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBoundary conditions of the open string Two movers (similar to progressive and regressive waves): left movers Ψµ , right movers Ψµ . + − at σ = 0 we take: Ψ+ (0, τ ) = Ψ− (0, τ ) µ µ Two types of boundary conditions at σ = π (called sectors): Ioan Muntean String Theory: Explanation and Fundamentalism
- 387. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBoundary conditions of the open string Two movers (similar to progressive and regressive waves): left movers Ψµ , right movers Ψµ . + − at σ = 0 we take: Ψ+ (0, τ ) = Ψ− (0, τ ) µ µ Two types of boundary conditions at σ = π (called sectors): Ramond (R) sector: Ψ+ (π, τ ) = Ψ− (π, τ ) µ µ Ioan Muntean String Theory: Explanation and Fundamentalism
- 388. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBoundary conditions of the open string Two movers (similar to progressive and regressive waves): left movers Ψµ , right movers Ψµ . + − at σ = 0 we take: Ψ+ (0, τ ) = Ψ− (0, τ ) µ µ Two types of boundary conditions at σ = π (called sectors): Ramond (R) sector: Ψ+ (π, τ ) = Ψ− (π, τ ) µ µ Neveu-Schwarz (NS) sector: Ψ+ (π, τ ) = −Ψ− (π, τ ) µ µ Ioan Muntean String Theory: Explanation and Fundamentalism
- 389. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesBoundary conditions of the open string Two movers (similar to progressive and regressive waves): left movers Ψµ , right movers Ψµ . + − at σ = 0 we take: Ψ+ (0, τ ) = Ψ− (0, τ ) µ µ Two types of boundary conditions at σ = π (called sectors): Ramond (R) sector: Ψ+ (π, τ ) = Ψ− (π, τ ) µ µ Neveu-Schwarz (NS) sector: Ψ+ (π, τ ) = −Ψ− (π, τ ) µ µ Each b.c. gives diﬀerent spectra. Moreover there are now 8 combinations: open/closed strings, R/NS sectors, left/right movers Ioan Muntean String Theory: Explanation and Fundamentalism
- 390. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesMore spectra Each sector has its own spectrum: Ioan Muntean String Theory: Explanation and Fundamentalism
- 391. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesMore spectra Each sector has its own spectrum: The R sector: µ µ Ψ− (σ, τ ) = √1 2 n dn e −in(τ −σ) Ψµ (σ, τ ) = + √1 2 n µ dn e −in(τ +σ) Ioan Muntean String Theory: Explanation and Fundamentalism
- 392. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesMore spectra Each sector has its own spectrum: The R sector: µ µ Ψ− (σ, τ ) = √1 2 n dn e −in(τ −σ) Ψµ (σ, τ ) = + √1 2 n µ dn e −in(τ +σ) the NS sector: µ µ Ψ− (σ, τ ) = √1 2 r br e −ir (τ −σ) Ψµ (σ, τ ) = − √1 2 r µ br e −ir (τ +σ) Ioan Muntean String Theory: Explanation and Fundamentalism
- 393. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQuantization in RNS Ioan Muntean String Theory: Explanation and Fundamentalism
- 394. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQuantization in RNS Same procedure, but on the Majorana spinor. Ioan Muntean String Theory: Explanation and Fundamentalism
- 395. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQuantization in RNS Same procedure, but on the Majorana spinor. Constraints to eliminate the negative norm states are called super-Virasoro constraints. Ioan Muntean String Theory: Explanation and Fundamentalism
- 396. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQuantization in RNS Same procedure, but on the Majorana spinor. Constraints to eliminate the negative norm states are called super-Virasoro constraints. Negative norm states can be eliminated as in bosonic ST. Ioan Muntean String Theory: Explanation and Fundamentalism
- 397. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQuantization in RNS Same procedure, but on the Majorana spinor. Constraints to eliminate the negative norm states are called super-Virasoro constraints. Negative norm states can be eliminated as in bosonic ST. Lorentz invariance is recovered Ioan Muntean String Theory: Explanation and Fundamentalism
- 398. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesQuantization in RNS Same procedure, but on the Majorana spinor. Constraints to eliminate the negative norm states are called super-Virasoro constraints. Negative norm states can be eliminated as in bosonic ST. Lorentz invariance is recovered As a result, D=10. Ioan Muntean String Theory: Explanation and Fundamentalism
- 399. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSidestep: “simple” equations in ST? Ioan Muntean String Theory: Explanation and Fundamentalism
- 400. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSidestep: “simple” equations in ST? Maybe the equation of motion of a superstring in light-coordinate: ∂+ Ψµ = ∂− Ψµ = 0 − + ∂+ ∂− X µ = 0 Ioan Muntean String Theory: Explanation and Fundamentalism
- 401. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSidestep: “simple” equations in ST? Maybe the equation of motion of a superstring in light-coordinate: ∂+ Ψµ = ∂− Ψµ = 0 − + ∂+ ∂− X µ = 0 And its conservation laws: ∂+ Ψµ = ∂− Ψµ = 0 − + ∂− T++ = ∂+ T−− = 0 Ioan Muntean String Theory: Explanation and Fundamentalism
- 402. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSidestep: “simple” equations in ST? Maybe the equation of motion of a superstring in light-coordinate: ∂+ Ψµ = ∂− Ψµ = 0 − + ∂+ ∂− X µ = 0 And its conservation laws: ∂+ Ψµ = ∂− Ψµ = 0 − + ∂− T++ = ∂+ T−− = 0 can ﬁt on a t-shirt Ioan Muntean String Theory: Explanation and Fundamentalism
- 403. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model Ioan Muntean String Theory: Explanation and Fundamentalism
- 404. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model In GS (Green-Schwarz, mainly in ?) model, you put the SUSY on the real spacetime coordinates Ioan Muntean String Theory: Explanation and Fundamentalism
- 405. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model In GS (Green-Schwarz, mainly in ?) model, you put the SUSY on the real spacetime coordinates Space becomes space+superspace Ioan Muntean String Theory: Explanation and Fundamentalism
- 406. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model In GS (Green-Schwarz, mainly in ?) model, you put the SUSY on the real spacetime coordinates Space becomes space+superspace Coordinates are enlarge to: Ioan Muntean String Theory: Explanation and Fundamentalism
- 407. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model In GS (Green-Schwarz, mainly in ?) model, you put the SUSY on the real spacetime coordinates Space becomes space+superspace Coordinates are enlarge to: (you bet) super-coordinates. θA (Grassman variables) Ioan Muntean String Theory: Explanation and Fundamentalism
- 408. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model In GS (Green-Schwarz, mainly in ?) model, you put the SUSY on the real spacetime coordinates Space becomes space+superspace Coordinates are enlarge to: (you bet) super-coordinates. θA (Grassman variables) Super coordinates anticommute (unlike coordinates). Ioan Muntean String Theory: Explanation and Fundamentalism
- 409. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model In GS (Green-Schwarz, mainly in ?) model, you put the SUSY on the real spacetime coordinates Space becomes space+superspace Coordinates are enlarge to: (you bet) super-coordinates. θA (Grassman variables) Super coordinates anticommute (unlike coordinates). On the worldsheet we have: Ioan Muntean String Theory: Explanation and Fundamentalism
- 410. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model In GS (Green-Schwarz, mainly in ?) model, you put the SUSY on the real spacetime coordinates Space becomes space+superspace Coordinates are enlarge to: (you bet) super-coordinates. θA (Grassman variables) Super coordinates anticommute (unlike coordinates). On the worldsheet we have: 1 X µ (σ, θ) and Ioan Muntean String Theory: Explanation and Fundamentalism
- 411. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model In GS (Green-Schwarz, mainly in ?) model, you put the SUSY on the real spacetime coordinates Space becomes space+superspace Coordinates are enlarge to: (you bet) super-coordinates. θA (Grassman variables) Super coordinates anticommute (unlike coordinates). On the worldsheet we have: 1 X µ (σ, θ) and 2 Θa (σ, θ) ﬁelds. Ioan Muntean String Theory: Explanation and Fundamentalism
- 412. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model In GS (Green-Schwarz, mainly in ?) model, you put the SUSY on the real spacetime coordinates Space becomes space+superspace Coordinates are enlarge to: (you bet) super-coordinates. θA (Grassman variables) Super coordinates anticommute (unlike coordinates). On the worldsheet we have: 1 X µ (σ, θ) and 2 Θa (σ, θ) ﬁelds. Each term contribute to the symmetry of the action and has a super-Poincare group. Ioan Muntean String Theory: Explanation and Fundamentalism
- 413. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesSUSY of the spacetime and the GS model In GS (Green-Schwarz, mainly in ?) model, you put the SUSY on the real spacetime coordinates Space becomes space+superspace Coordinates are enlarge to: (you bet) super-coordinates. θA (Grassman variables) Super coordinates anticommute (unlike coordinates). On the worldsheet we have: 1 X µ (σ, θ) and 2 Θa (σ, θ) ﬁelds. Each term contribute to the symmetry of the action and has a super-Poincare group. The Θ ﬁeld has a special symmetry called “Kappa symmetry”. Ioan Muntean String Theory: Explanation and Fundamentalism
- 414. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesGS quantization Ioan Muntean String Theory: Explanation and Fundamentalism
- 415. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesGS quantization Very diﬃcult to quantize Ioan Muntean String Theory: Explanation and Fundamentalism
- 416. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesGS quantization Very diﬃcult to quantize Needs special decomposition Ioan Muntean String Theory: Explanation and Fundamentalism
- 417. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHow many super-symmetries? Ioan Muntean String Theory: Explanation and Fundamentalism
- 418. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHow many super-symmetries? There is no sense to have N > 2. Ioan Muntean String Theory: Explanation and Fundamentalism
- 419. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHow many super-symmetries? There is no sense to have N > 2. Usually two cases: Ioan Muntean String Theory: Explanation and Fundamentalism
- 420. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHow many super-symmetries? There is no sense to have N > 2. Usually two cases: N=1, one Grassman number, one fermionic coordinate, hence Type-I ST Ioan Muntean String Theory: Explanation and Fundamentalism
- 421. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesHow many super-symmetries? There is no sense to have N > 2. Usually two cases: N=1, one Grassman number, one fermionic coordinate, hence Type-I ST N=2 there are two fermionic coordinates (spinors) on the worldsheet, hence Type-II ST Ioan Muntean String Theory: Explanation and Fundamentalism
- 422. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesD-branes are for Yang-Mills ﬁelds Ioan Muntean String Theory: Explanation and Fundamentalism
- 423. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesD-branes are for Yang-Mills ﬁelds They exist in the spacetime and they are the surfaces where strings end. Ioan Muntean String Theory: Explanation and Fundamentalism
- 424. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesD-branes are for Yang-Mills ﬁelds They exist in the spacetime and they are the surfaces where strings end. they mesh well with non-supersymmetric ST (such as bosonic ST) but better with superstring theory. Ioan Muntean String Theory: Explanation and Fundamentalism
- 425. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesD-branes are for Yang-Mills ﬁelds They exist in the spacetime and they are the surfaces where strings end. they mesh well with non-supersymmetric ST (such as bosonic ST) but better with superstring theory. D-branes are usually used to infer all forces of the Standard Model. Ioan Muntean String Theory: Explanation and Fundamentalism
- 426. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesD-branes are for Yang-Mills ﬁelds They exist in the spacetime and they are the surfaces where strings end. they mesh well with non-supersymmetric ST (such as bosonic ST) but better with superstring theory. D-branes are usually used to infer all forces of the Standard Model. The current understanding is that gravitation escapes the branes. Ioan Muntean String Theory: Explanation and Fundamentalism
- 427. Some assumptions String uniﬁcation Philosophy and Quantum Gravity programs Problems at the foundation Explanation and string theory SUSY = Super-symmetry The nutshell version of string theory Skip: Background dependence Some case studies of string explanations The toy bosonic string theory Rejoinders and Conclusion Two SUSYs The D-branesD-branes are for Yang-Mills ﬁelds They exist in the spacetime and they are the surfaces where strings end. they mesh well with non-supersymmetric ST (such as bosonic ST) but better with superstring theory. D-branes are usually used to infer all forces of the Standard Model. The current understanding is that gravitation escapes the branes. N=2 there are two fermionic coordinates (spinors) on the worldsheet, hence Type-II ST Ioan Muntean String Theory: Explanation and Fundamentalism
- 428. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionWhat string explanation could look like Some constraints do explain in string theory. Ioan Muntean String Theory: Explanation and Fundamentalism
- 429. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionWhat string explanation could look like Some constraints do explain in string theory. By eliminating the ghost ﬁeld in bosonic string theory you get a spin-2 ﬁeld Ioan Muntean String Theory: Explanation and Fundamentalism
- 430. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionWhat string explanation could look like Some constraints do explain in string theory. By eliminating the ghost ﬁeld in bosonic string theory you get a spin-2 ﬁeld In order to eliminate tachyons one needs to move to supersymmetry Ioan Muntean String Theory: Explanation and Fundamentalism
- 431. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionWhat string explanation could look like Some constraints do explain in string theory. By eliminating the ghost ﬁeld in bosonic string theory you get a spin-2 ﬁeld In order to eliminate tachyons one needs to move to supersymmetry explaining away anomalies of the standard model one can gain insight into the nature of the duality between bosons and fermions Ioan Muntean String Theory: Explanation and Fundamentalism
- 432. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionWhat string explanation could look like Some constraints do explain in string theory. By eliminating the ghost ﬁeld in bosonic string theory you get a spin-2 ﬁeld In order to eliminate tachyons one needs to move to supersymmetry explaining away anomalies of the standard model one can gain insight into the nature of the duality between bosons and fermions all these look like unexpected explanations (and some actually work) Ioan Muntean String Theory: Explanation and Fundamentalism
- 433. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionWhat string explanation could look like Some constraints do explain in string theory. By eliminating the ghost ﬁeld in bosonic string theory you get a spin-2 ﬁeld In order to eliminate tachyons one needs to move to supersymmetry explaining away anomalies of the standard model one can gain insight into the nature of the duality between bosons and fermions all these look like unexpected explanations (and some actually work) Uniﬁcation is not necessarily the engine of these explanations. Ioan Muntean String Theory: Explanation and Fundamentalism
- 434. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFacts, constants, and string theory One can try to explain Λ, but it is not that easy. There are no-go results Ioan Muntean String Theory: Explanation and Fundamentalism
- 435. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFacts, constants, and string theory One can try to explain Λ, but it is not that easy. There are no-go results Explain why Newton’s constant is small by heterotic string theory in two regimes: strong coupling and weak coupling. Ioan Muntean String Theory: Explanation and Fundamentalism
- 436. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFacts, constants, and string theory One can try to explain Λ, but it is not that easy. There are no-go results Explain why Newton’s constant is small by heterotic string theory in two regimes: strong coupling and weak coupling. There are attempts to explain Big-Bang, SSB ,etc. by smoothing out singularities before Big-Bang Ioan Muntean String Theory: Explanation and Fundamentalism
- 437. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFacts, constants, and string theory One can try to explain Λ, but it is not that easy. There are no-go results Explain why Newton’s constant is small by heterotic string theory in two regimes: strong coupling and weak coupling. There are attempts to explain Big-Bang, SSB ,etc. by smoothing out singularities before Big-Bang Ioan Muntean String Theory: Explanation and Fundamentalism
- 438. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFermions out of string theory? Ioan Muntean String Theory: Explanation and Fundamentalism
- 439. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFermions out of string theory? Can we infer fermions? No Ioan Muntean String Theory: Explanation and Fundamentalism
- 440. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFermions out of string theory? Can we infer fermions? No But we can write down the fermionic and bosonic ﬁelds Ioan Muntean String Theory: Explanation and Fundamentalism
- 441. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFermions out of string theory? Can we infer fermions? No But we can write down the fermionic and bosonic ﬁelds Is this enough? Ioan Muntean String Theory: Explanation and Fundamentalism
- 442. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFermions out of string theory? Can we infer fermions? No But we can write down the fermionic and bosonic ﬁelds Is this enough? No, the usual Yang-Mills symmetries are missing. Ioan Muntean String Theory: Explanation and Fundamentalism
- 443. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFermions out of string theory? Can we infer fermions? No But we can write down the fermionic and bosonic ﬁelds Is this enough? No, the usual Yang-Mills symmetries are missing. ST in this formulation does not produce YM symmetries, but fermionic ﬁelds Ioan Muntean String Theory: Explanation and Fundamentalism
- 444. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionFermions out of string theory? Can we infer fermions? No But we can write down the fermionic and bosonic ﬁelds Is this enough? No, the usual Yang-Mills symmetries are missing. ST in this formulation does not produce YM symmetries, but fermionic ﬁelds These are not physical or spacetime bosons and fermions. Ioan Muntean String Theory: Explanation and Fundamentalism
- 445. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionStandard Model out of string theory? Go statistical Ioan Muntean String Theory: Explanation and Fundamentalism
- 446. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionStandard Model out of string theory? Go statistical It is possible and doable Ioan Muntean String Theory: Explanation and Fundamentalism
- 447. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionStandard Model out of string theory? Go statistical It is possible and doable But: too many consistent string models that do the explanatory job Ioan Muntean String Theory: Explanation and Fundamentalism
- 448. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionStandard Model out of string theory? Go statistical It is possible and doable But: too many consistent string models that do the explanatory job String theory needs to explain its own limitation and the choice of the right model Ioan Muntean String Theory: Explanation and Fundamentalism
- 449. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionStandard Model out of string theory? Go statistical It is possible and doable But: too many consistent string models that do the explanatory job String theory needs to explain its own limitation and the choice of the right model YOu need to explain your choice of string model. You can do this by a statistical approach to models. Ioan Muntean String Theory: Explanation and Fundamentalism
- 450. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionStandard Model out of string theory? Go statistical It is possible and doable But: too many consistent string models that do the explanatory job String theory needs to explain its own limitation and the choice of the right model YOu need to explain your choice of string model. You can do this by a statistical approach to models. String theory needs the concept of naturalness Ioan Muntean String Theory: Explanation and Fundamentalism
- 451. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionGSO projection: a farewell to tachyons Ioan Muntean String Theory: Explanation and Fundamentalism
- 452. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionGSO projection: a farewell to tachyons Several attempts were made in order to eliminate tachyons Ioan Muntean String Theory: Explanation and Fundamentalism
- 453. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionGSO projection: a farewell to tachyons Several attempts were made in order to eliminate tachyons But the RNS still contains the annoying tachyonic ﬁeld. Ioan Muntean String Theory: Explanation and Fundamentalism
- 454. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionGSO projection: a farewell to tachyons Several attempts were made in order to eliminate tachyons But the RNS still contains the annoying tachyonic ﬁeld. There is a procedure called GSO (Gliozzi, Scherk, Olive) (?, Ch. 4) Ioan Muntean String Theory: Explanation and Fundamentalism
- 455. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionGSO projection: a farewell to tachyons Several attempts were made in order to eliminate tachyons But the RNS still contains the annoying tachyonic ﬁeld. There is a procedure called GSO (Gliozzi, Scherk, Olive) (?, Ch. 4) a parity operator G is deﬁned (determines the number of fermionic oscillations). Ioan Muntean String Theory: Explanation and Fundamentalism
- 456. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionGSO projection: a farewell to tachyons Several attempts were made in order to eliminate tachyons But the RNS still contains the annoying tachyonic ﬁeld. There is a procedure called GSO (Gliozzi, Scherk, Olive) (?, Ch. 4) a parity operator G is deﬁned (determines the number of fermionic oscillations). we keep only the states with a positive G-parity. Ioan Muntean String Theory: Explanation and Fundamentalism
- 457. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionGSO projection: a farewell to tachyons Several attempts were made in order to eliminate tachyons But the RNS still contains the annoying tachyonic ﬁeld. There is a procedure called GSO (Gliozzi, Scherk, Olive) (?, Ch. 4) a parity operator G is deﬁned (determines the number of fermionic oscillations). we keep only the states with a positive G-parity. this eliminates tachyons. Ioan Muntean String Theory: Explanation and Fundamentalism
- 458. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionUnexpected failures: some morals Ioan Muntean String Theory: Explanation and Fundamentalism
- 459. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionUnexpected failures: some morals RNS model is not able to eliminate tachyons without the GSO projection condition Ioan Muntean String Theory: Explanation and Fundamentalism
- 460. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionUnexpected failures: some morals RNS model is not able to eliminate tachyons without the GSO projection condition the GSO in general is considered ad-hoc Ioan Muntean String Theory: Explanation and Fundamentalism
- 461. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionUnexpected failures: some morals RNS model is not able to eliminate tachyons without the GSO projection condition the GSO in general is considered ad-hoc RNS model is not able to infer the Standard Model Ioan Muntean String Theory: Explanation and Fundamentalism
- 462. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionUnexpected failures: some morals RNS model is not able to eliminate tachyons without the GSO projection condition the GSO in general is considered ad-hoc RNS model is not able to infer the Standard Model that is possible only with: Ioan Muntean String Theory: Explanation and Fundamentalism
- 463. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionUnexpected failures: some morals RNS model is not able to eliminate tachyons without the GSO projection condition the GSO in general is considered ad-hoc RNS model is not able to infer the Standard Model that is possible only with: D-branes OR Ioan Muntean String Theory: Explanation and Fundamentalism
- 464. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionUnexpected failures: some morals RNS model is not able to eliminate tachyons without the GSO projection condition the GSO in general is considered ad-hoc RNS model is not able to infer the Standard Model that is possible only with: D-branes OR Charges on the endpoints of strings AND Ioan Muntean String Theory: Explanation and Fundamentalism
- 465. Philosophy and Quantum Gravity programs Explanation and string theory Naive explanations The nutshell version of string theory Sophisticated cases of string explanations Some case studies of string explanations Rejoinders and ConclusionUnexpected failures: some morals RNS model is not able to eliminate tachyons without the GSO projection condition the GSO in general is considered ad-hoc RNS model is not able to infer the Standard Model that is possible only with: D-branes OR Charges on the endpoints of strings AND SUSY on the spacetime manifold (the GS model) Ioan Muntean String Theory: Explanation and Fundamentalism
- 466. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionRejoinders Why do you decouple uniﬁcation from explanation? Ioan Muntean String Theory: Explanation and Fundamentalism
- 467. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionRejoinders Why do you decouple uniﬁcation from explanation? Are these indeed explanations or mere consequences of the string mathematics? Ioan Muntean String Theory: Explanation and Fundamentalism
- 468. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionRejoinders Why do you decouple uniﬁcation from explanation? Are these indeed explanations or mere consequences of the string mathematics? If there is such an explanatory mismatch, do we still talk about string theory and a fundamental theory? It is a good candidate for the ultimate/GUT? Ioan Muntean String Theory: Explanation and Fundamentalism
- 469. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionRejoinders Why do you decouple uniﬁcation from explanation? Are these indeed explanations or mere consequences of the string mathematics? If there is such an explanatory mismatch, do we still talk about string theory and a fundamental theory? It is a good candidate for the ultimate/GUT? can you connect explanatory advantages to prediction/conﬁrmation advantages? If not, is this science? Ioan Muntean String Theory: Explanation and Fundamentalism
- 470. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionA suggestion Perhaps we need to look at string explanations in the same way we bridge by explanation the domain of psychology and neuroscience Ioan Muntean String Theory: Explanation and Fundamentalism
- 471. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionA suggestion Perhaps we need to look at string explanations in the same way we bridge by explanation the domain of psychology and neuroscience Not all physical events of the brain are mirrored onto a mental state and viceversa Ioan Muntean String Theory: Explanation and Fundamentalism
- 472. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionA suggestion Perhaps we need to look at string explanations in the same way we bridge by explanation the domain of psychology and neuroscience Not all physical events of the brain are mirrored onto a mental state and viceversa There is an explanatory gap there. Ioan Muntean String Theory: Explanation and Fundamentalism
- 473. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionA suggestion Perhaps we need to look at string explanations in the same way we bridge by explanation the domain of psychology and neuroscience Not all physical events of the brain are mirrored onto a mental state and viceversa There is an explanatory gap there. String theory is not completely explanatory when it comes to Standard Model and General Relativity Ioan Muntean String Theory: Explanation and Fundamentalism
- 474. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionA suggestion Perhaps we need to look at string explanations in the same way we bridge by explanation the domain of psychology and neuroscience Not all physical events of the brain are mirrored onto a mental state and viceversa There is an explanatory gap there. String theory is not completely explanatory when it comes to Standard Model and General Relativity Reduction does not work here. Ioan Muntean String Theory: Explanation and Fundamentalism
- 475. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionConclusion There is explanation at work in string theory Ioan Muntean String Theory: Explanation and Fundamentalism
- 476. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionConclusion There is explanation at work in string theory IT does not look strongly coupled to uniﬁcaiton Ioan Muntean String Theory: Explanation and Fundamentalism
- 477. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionConclusion There is explanation at work in string theory IT does not look strongly coupled to uniﬁcaiton It is novel and unexpected Ioan Muntean String Theory: Explanation and Fundamentalism
- 478. Philosophy and Quantum Gravity programs Explanation and string theory The nutshell version of string theory Some case studies of string explanations Rejoinders and ConclusionReferences I Ioan Muntean String Theory: Explanation and Fundamentalism

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