2010 11 psa montreal explanation and fundamentalism

Philosophy and Quantum Gravity programs
Explanation and string theory
The nutshell version of string theory
Some case studies of string explanations
Rejoinders and Conclusion

String 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

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?

Two 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





1 ambitious and reformist (integrated in a form of scientism).
Useful for metaphysics
2 useful in philosophy of science/physics. Can be normative
...



1 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?




Question Q1

In most cases, QG are prescriptive in respect of time, space,
quantization etc.




Question Q1

In most cases, QG are prescriptive in respect of time, space,
quantization etc.
???????


Philosophers should be doing this!
Sometimes philosophers help with insights in the problem of
space, time, change, dynamics, etc.



Philosophers 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


1’. 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.




Part-whole relations and QG.
For Structural Realism and QG see ?



2. 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

Question Q2’
Which Quantum Gravity program has the drawback D?




Question Q2

Question Q2’

This is discussed by fewer philosophers ???




Question Q2

Question Q2’

This is discussed by fewer philosophers ???
I plan to follow something similar here



A narrow scope



A narrow scope
I give up the comparative aspects of Q2 and Q2’and focus on
one QG program



A narrow scope
one QG program
Question
Is string theory a successful QG program?



A narrow scope
one QG program
Question
Dimensions of success of theories:



A narrow scope
one QG program
Question
1 Empirical conﬁrmation (preferably direct)



A narrow scope
one QG program
Question
2 Predictive success (preferably novel)



A narrow scope
one QG program
Question
3 Non-empirical virtues: uniﬁcation, explanation, elegance,
simplicity



A narrow scope
one QG program
Question
simplicity
4 Problem solving (preferably real problems), etc.



A narrow scope
one QG program
Question
simplicity
5 Fecundity



A narrow scope
one QG program
Question
simplicity
5 Fecundity
6 Meshing well with other scientiﬁc theories



A narrow scope
one QG program
Question
simplicity
5 Fecundity
6 Meshing well with other scientiﬁc theories
None of them is necessary and suﬃcient.


Some reasons to . . . love string theory



It solves some problems:



the ultraviolet divergences of General Relativity and of
Standard Model.



Standard Model.
no dimensionless free parameters.



Standard Model.
Is the dominant research program in quantum gravity (QG)



Standard Model.
Is the (leading?) contender for a theory of everything:



Standard Model.
Advertised as: “a single theory that, in principle is capable of
describing all phenomena” ((?, ix)).



Standard Model.
Heavily advertised in popularizing literature, perhaps the best
known quantum gravity program



Standard Model.
Could tell us new stories about the world:



Standard Model.
can talk evolution of the universe before the Big Bang
(interpreted as a collision of branes)



Standard Model.
explains facts about black holes, dark matter etc.


Standard Model.
explains facts about black holes, dark matter etc.
But these are promises and prospective Explanation and Fundamentalism
Ioan Muntean String Theory:
undertakings


More reasons to. . . love ST




It is “science in the making”




It is mathematically fertile and can provide “mathematical
predictions” (?)




predictions” (?)
It is open to interpretive questions (?)




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



Amendments



Amendments

String theory does not have the features of a scientiﬁc theory



Amendments

Call it a program/direction of research, not a theory



Amendments

Interpret it as a collection of mathematical models



Amendments

1 each model is false and has intentional falsities inserted



Amendments

2 the model does not latch onto the world



Amendments

string theory does not explains facts, at least not directly.



Amendments

string theory does not explains facts, at least not directly.
it may predict mathematical facts or even provide
mathematical results



Some 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




closet
String theory:




closet
String theory:
is background dependent (Smolin, Rovelli, Penrose)




closet
String theory:
does not seem to address deep philosophical issues (?)




closet
String theory:
never solved or addressed the measurement problem




closet
String theory:
All known string theories are perturbation theories




closet
String theory:
All known string theories are perturbation theories
String solutions are unstable (?)



A 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 ?)




Introduction to ?)
So does QFT, it involves a ﬁxed spacetime geometry (a
priori?)




Introduction to ?)
priori?)
But this is against the very principle of general relativity.




Introduction to ?)
priori?)
In String Theory geometry is not dynamical anymore.




Introduction to ?)
priori?)
In String Theory geometry is not dynamical anymore.
It is like the “unmoved mover” or the ether.



The prodigal ST



The 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))



The prodigal ST

another.” ((?, 159))
Roughly speaking, ST replicates the mistake of Newtonian
physics and overlooks some central achievements of GR.



The prodigal ST

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.



Bleak philosophy of string theory: conﬁrmation and
prediction

Is ST conﬁrmed directly?



prediction

No, it is not.



prediction

No, it is not.
Is ST successful in providing novel predictions?



prediction

No, it is not.
No, it is not.



prediction

No, it is not.
No, it is not.
Some predictions are in sight in “string cosmology” or stringy
black holes



prediction

No, it is not.
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.



Apply GOF falsiﬁcationism to string theory?




No data, no falsiﬁcation, no science




Hence string theory is closer to:




Mathematics




Mathematics
Metaphysics




Mathematics
Metaphysics
Speculation




Mathematics
Metaphysics
Speculation
Mysticism, new-age cults or even religion (it creates its own
lingo).




Mathematics
Metaphysics
Speculation
lingo).
Some deemed ST (and QG) as “postmodern physics”
(Nambu)




Mathematics
Metaphysics
Speculation
lingo).
Some deemed ST (and QG) as “postmodern physics”
(Nambu)
Several physicists aired these worries: L. Smolin, P. Woit, R.
Penrose



Experimental agnosticism

Stay agnostic about its direct experimental conﬁrmation





“Test me if you can!”





“Test me if you can!”

Credits go to
http://icanhascheeseburger.com


Less bleak philosophy of string theory: some virtues




What theoretical dimensions of scientiﬁc success are known?




1 Uniﬁcation




1 Uniﬁcation
2 Explanation




1 Uniﬁcation
2 Explanation
3 Elegancy, Cohesion, Beauty, Simplicity, you name it. . .




1 Uniﬁcation
2 Explanation
4 Problem Solving




1 Uniﬁcation
2 Explanation
4 Problem Solving
1 is obvious and recognized as such (but deserves attention,
too)




1 Unification
2 Explanation
4 Problem Solving
too)
3 difficult to define, vague, ambiguous




1 Uniﬁcation
2 Explanation
4 Problem Solving
too)
4 is a interesting topic in itself (Ex: string and anomalies)




1 Uniﬁcation
2 Explanation
4 Problem Solving
too)
Here I tackle 2 and relatedly, 1.




1 Uniﬁcation
2 Explanation
4 Problem Solving
too)
Here I tackle 2 and relatedly, 1.
Why 2?



Does 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.


2010 11 psa montreal explanation and fundamentalism

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