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

1. Big Questions in Science
Sebastian de Haro, fall 2012

2. Big Questions in Science, fall 2012. SdH, AUC 2

3. Big Questions in Science, fall 2012. SdH, AUC 3

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6. Robbert Dijkgraaf NRC 05-05-11: Total amount of
Information on earth is 1 zettabyte bytes
Big Questions in Science, fall 2012. SdH, AUC 6

7. 1 bit
Big Questions in Science, fall 2012. SdH, AUC
2011. 7

8.  Wave-like pattern encoded in wave function:
Big Questions in Science, fall 2012. SdH, AUC 8

9.  Wave propagation
Big Questions in Science, fall 2012. SdH, AUC 9

10. Big Questions in Science, fall 2012. SdH, AUC 10

11. “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

12. Big Questions in Science, fall 2012. SdH, AUC 12

13. Big Questions in Science, fall 2012. SdH, AUC 13

14. ?
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15.  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

16. The rest
Biology
Chemistry
Statistical physics/condensed matter
Quantum mechanics/relativity/class.mech
Particle physics / gravity
String Theory, M-theory
Big Questions in Science, fall 2012. SdH, AUC 16

17.  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

18.  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

19.  “By far the most important [prediction] is super symmetry
which is fundamental to most attempts to unify Einstein's
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

20. 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

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23.  Singularities
 Big Bang
 Black Holes
 The problem of infinities
 Most serious: information loss
Big Questions in Science, fall 2012. SdH, AUC 23

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26.  Pierre-Simon Laplace (1749-1827).
 Escape velocity.
 Earth:
 ‘Black star’:
Big Questions in Science, fall 2012. SdH, AUC 26

27.  Einstein 1915: mass implies curvature of space-time.
 Curvature is perceived as gravitational attraction.
Big Questions in Science, fall 2012. SdH, AUC 27

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 28

29.  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

30.  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

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33.  Free fall.
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34.  Heaviest objects, not even light can escape.
 Fish in the water analogy.
 Free fall.
Big Questions in Science, fall 2012. SdH, AUC 34

35.  1973 Bekenstein develops black hole thermodynamics.
 1974 Hawking: black holes emit radiation.
 The key: quantum fluctuations of vacuum.
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36. Big Questions in Science, fall 2012. SdH, AUC 36

37. Hawking Radiation
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38.  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

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41.  Black holes emit radiation.
 The radiation is thermal, contains no information.
 Information is lost.
 New level of unpredictability in physics.
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51.  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

52.  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

53.  ’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

54. There is no baby universe branching off, as I once thought. The
information remains firmly in our universe. I’m sorry to disappoint
science fiction fans, but if information is preserved, there is no
possibility of using black holes to travel to other universes. If you
jump into a black hole, your energy will be returned to our universe
but in a mangled form which contains the information about what
you were like but in a state where it can not be easily recognized. It
is like burning an encyclopedia. Information is not lost, if one keeps
the smoke and the ashes. But it is difficult to read. In 1997, Kip
Thorne and I, bet John Preskill that information was lost in black
holes. The loser(s) of the bet were to provide the winner(s) with an
encyclopedia of their own choice, from which information can be
recovered with ease. I gave John an encyclopedia of baseball, but
maybe I should just have given him the ashes.
Big Questions in Science, fall 2012. SdH, AUC 54

55.  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

56.  Gravity 5d 4d particle physics (QCD)
 Gravity 4d 3d particle physics
Big Questions in Science, fall 2012. SdH, AUC 56

57. Temperature Hawking radiation Temperature material
Small perturbations of black hole Electrical and thermal
transport properties
(conductivity)
Big Questions in Science, fall 2012. SdH, AUC 57

58.  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

59. Long-distance cutoff UV cutoff
Big Questions in Science, fall 2012. SdH, AUC 59

60.  Gravity seems equivalent with physics of
conducting materials
 Also connections with hydrodynamics
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61. Big Questions in Science, fall 2012. SdH, AUC 61

62. Big Questions in Science, fall 2012. SdH, AUC 62

63. Big Bang
String Theory Cosmology
Astronomy
Particle Physics
Quantum Mechanics
Oceanography
Chemistry
Biology Geology
Medicine
Sheldon Glashow
(1975)
Big Questions in Science, fall 2012. SdH, AUC 63

64.  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