9 What Is Reality?
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9 What Is Reality?

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Big Questions in Science series, (9 of 9). Class taught at AUC (University of Amsterdam) during the 2012-2013 fall semester.

Big Questions in Science series, (9 of 9). Class taught at AUC (University of Amsterdam) during the 2012-2013 fall semester.

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9 What Is Reality? 9 What Is Reality? Presentation Transcript

  • Big Questions in ScienceSebastian de Haro, fall 2012
  • Big Questions in Science, fall 2012. SdH, AUC 2
  • Big Questions in Science, fall 2012. SdH, AUC 3
  • Big Questions in Science, fall 2012. SdH, AUC 4
  • Big Questions in Science, fall 2012. SdH, AUC 5
  • Robbert Dijkgraaf NRC 05-05-11: Total amount ofInformation on earth is 1 zettabyte bytes Big Questions in Science, fall 2012. SdH, AUC 6
  • 1 bitBig Questions in Science, fall 2012. SdH, AUC 2011. 7
  •  Wave-like pattern encoded in wave function: Big Questions in Science, fall 2012. SdH, AUC 8
  •  Wave propagation Big Questions in Science, fall 2012. SdH, AUC 9
  • Big Questions in Science, fall 2012. SdH, AUC 10
  • “Traditionally these are questions for philosophy, but philosophy is dead. Philosophy has not kept up with modern developments in science, particularly physics. Scientists have become the bearers of the torch of discovery in our quest for knowledge. The purpose of this book is to give the answers that are suggested by recent discoveries and theoretical advances. They lead us to a new picture of the universe and our place in it that is very different from the traditional one, and different even from the picture we might have painted just a decade or two ago. Still, the first sketches of the new concept can be traced back almost a century.” (The Grand Design).Big Questions in Science, fall 2012. SdH, AUC 11
  • Big Questions in Science, fall 2012. SdH, AUC 12
  • Big Questions in Science, fall 2012. SdH, AUC 13
  • ?Big Questions in Science, fall 2012. SdH, AUC 14
  •  Steven Weinberg:  Petty reductionism: whole to parts.  Grand reductionism: “To reduce the world of physical phenomena to a finite set of fundamental equations (or principles)” (Freeman Dyson). “Search for the common source of all explanations.” Big Questions in Science, fall 2012. SdH, AUC 15
  • The rest Biology ChemistryStatistical physics/condensed matterQuantum mechanics/relativity/class.mech Particle physics / gravity String Theory, M-theory Big Questions in Science, fall 2012. SdH, AUC 16
  •  Weinberg: “One of the members of the [SSC] board argued that we should not give the impression that we think that elementary particle physics is more fundamental than other fields, because it just tended to enrage our friends in other areas of physics. The reason we give the impression that we think that elementary particle physics is more fundamental than other branches of physics is because it is. I do not know how to defend the amounts being spent on particle physics without being frank about this.” Big Questions in Science, fall 2012. SdH, AUC 17
  •  Philip Anderson: “They [the results of particle physics] are in no sense more fundamental than what Alan Turing did in founding the computer science, or what Francis Crick and James Watson did in discovering the secret of life.” Big Questions in Science, fall 2012. SdH, AUC 18
  •  “By far the most important [prediction] is super symmetry which is fundamental to most attempts to unify Einsteins General Relativity with Quantum Theory. This would be confirmed by the discovery of super partners to the particles that we already know. The Superconducting Super Collider (the SSC) was being built in Texas and would have reached the energies at which super partners were expected. However, the United States went through a fit of feeling poor and canceled the project half way. At the risk of causing embarrassment, I have to say I think this was a very short sighted decision. I hope that the US, and other governments will do better in the next millennium. (Stephen Hawking, Millennium lecture)” Big Questions in Science, fall 2012. SdH, AUC 19
  • Intermediate areas: Therest De rest Biology Chemistry Statistical physics/condensed matter Quantum mechanics/relativity/class.mech Particle physics / gravity String Theory, M-theory Snaartheorie, M-theorie Big Questions in Science, fall 2012. SdH, AUC 20
  • Big Questions in Science, fall 2012. SdH, AUC 21
  • Big Questions in Science, fall 2012. SdH, AUC 22
  •  Singularities  Big Bang  Black Holes The problem of infinities Most serious: information loss Big Questions in Science, fall 2012. SdH, AUC 23
  • Big Questions in Science, fall 2012. SdH, AUC 24
  • Big Questions in Science, fall 2012. SdH, AUC 25
  •  Pierre-Simon Laplace (1749-1827).  Escape velocity.  Earth:  ‘Black star’: Big Questions in Science, fall 2012. SdH, AUC 26
  •  Einstein 1915: mass implies curvature of space-time. Curvature is perceived as gravitational attraction. Big Questions in Science, fall 2012. SdH, AUC 27
  •  Black hole itself cannot be seen. Indirect evidence: matter swallowed up by supermassive black object. Predictions: time delay, gravitational lensing. Big Questions in Science, fall 2012. SdH, AUC 28
  •  Black hole itself cannot be seen. Indirect evidence: matter swallowed up by supermassive black object. Predictions: time delay, gravitational lensing. Big Questions in Science, fall 2012. SdH, AUC 29
  •  If as heavy as the sun: one meter. Supermassive (one million suns): size of the solar system. Milky Way: Sagittarius A*. Big Questions in Science, fall 2012. SdH, AUC 30
  • Big Questions in Science, fall 2012. SdH, AUC 31
  • Big Questions in Science, fall 2012. SdH, AUC 32
  •  Free fall. Big Questions in Science, fall 2012. SdH, AUC 33
  •  Heaviest objects, not even light can escape. Fish in the water analogy. Free fall. Big Questions in Science, fall 2012. SdH, AUC 34
  •  1973 Bekenstein develops black hole thermodynamics. 1974 Hawking: black holes emit radiation. The key: quantum fluctuations of vacuum. Big Questions in Science, fall 2012. SdH, AUC 35
  • Big Questions in Science, fall 2012. SdH, AUC 36
  • Hawking Radiation Big Questions in Science, fall 2012. SdH, AUC 37
  •  If we wait long enough, the black hole will evaporate. Radiation contains no information about what went in. Information disappears. Black holes violate quantum mechanics. Big Questions in Science, fall 2012. SdH, AUC 38
  • Big Questions in Science, fall 2012. SdH, AUC 39
  • Big Questions in Science, fall 2012. SdH, AUC 40
  •  Black holes emit radiation. The radiation is thermal, contains no information. Information is lost. New level of unpredictability in physics. Big Questions in Science, fall 2012. SdH, AUC 41
  • Big Questions in Science, fall 2012. SdH, AUC 42
  • Big Questions in Science, fall 2012. SdH, AUC 43
  • Big Questions in Science, fall 2012. SdH, AUC 44
  • Big Questions in Science, fall 2012. SdH, AUC 45
  • Big Questions in Science, fall 2012. SdH, AUC 46
  • Big Questions in Science, fall 2012. SdH, AUC 47
  • Big Questions in Science, fall 2012. SdH, AUC 48
  • Big Questions in Science, fall 2012. SdH, AUC 49
  • Big Questions in Science, fall 2012. SdH, AUC 50
  •  Alice and the cat have different descriptions of reality. Their points of view are mutually exclusive. Describe black hole from point of view of an observer. Led to holographic principle. Big Questions in Science, fall 2012. SdH, AUC 51
  •  1993 Gerard ’t Hooft Thought experiment: box volume E R Entropy: measure # states # S~E Gravity in the Bulk Theory on Boundary Big Questions in Science, fall 2012. SdH, AUC 52
  •  ’t Hooft 1993 “dimensional reduction” Susskind 1994 “holography” Maldacena 1997 holography in string theory 2004 Hawking admits he lost his bet Big Questions in Science, fall 2012. SdH, AUC 53
  • There is no baby universe branching off, as I once thought. Theinformation remains firmly in our universe. I’m sorry to disappointscience fiction fans, but if information is preserved, there is nopossibility of using black holes to travel to other universes. If youjump into a black hole, your energy will be returned to our universebut in a mangled form which contains the information about whatyou were like but in a state where it can not be easily recognized. Itis like burning an encyclopedia. Information is not lost, if one keepsthe smoke and the ashes. But it is difficult to read. In 1997, KipThorne and I, bet John Preskill that information was lost in blackholes. The loser(s) of the bet were to provide the winner(s) with anencyclopedia of their own choice, from which information can berecovered with ease. I gave John an encyclopedia of baseball, butmaybe I should just have given him the ashes. Big Questions in Science, fall 2012. SdH, AUC 54
  •  Black holes can radiate, which gives rise to information paradox Paradigm to solve this problem: holography – confirmed by string theory: the world is 3- not 4-dimensional Gravity is a “fake” force Implications for reductionism? Big Questions in Science, fall 2012. SdH, AUC 55
  •  Gravity 5d 4d particle physics (QCD) Gravity 4d 3d particle physics Big Questions in Science, fall 2012. SdH, AUC 56
  • Temperature Hawking radiation Temperature materialSmall perturbations of black hole Electrical and thermal transport properties (conductivity) Big Questions in Science, fall 2012. SdH, AUC 57
  •  Common element in all holographic dualities: “long” distances in one theory correspond to “short” distances in the other. Big Questions in Science, fall 2012. SdH, AUC 58
  • Long-distance cutoff UV cutoff Big Questions in Science, fall 2012. SdH, AUC 59
  •  Gravity seems equivalent with physics of conducting materials Also connections with hydrodynamics Big Questions in Science, fall 2012. SdH, AUC 60
  • Big Questions in Science, fall 2012. SdH, AUC 61
  • Big Questions in Science, fall 2012. SdH, AUC 62
  • Big Bang String Theory Cosmology AstronomyParticle PhysicsQuantum Mechanics Oceanography Chemistry Biology Geology Medicine Sheldon Glashow (1975) Big Questions in Science, fall 2012. SdH, AUC 63
  •  Contextual models with local overlaps and interaction within general framework. Unity: connection of distant areas (IR/UV). Important question: Fundamental variables? Answer may depend on physical context. Roger Penrose : Grand reductionism does not exclude (rather, necessitates) philosophy. Connection math, arts, ethics. Big Questions in Science, fall 2012. SdH, AUC 64