Nebula NGC3603

Multiverse or Universe

An evening of discussion about the concept of a
multiplicity of possible of actual universes

Wednesday, March 26, 2003, 8 pm - 10 pm
TCSEQ, Room 200, Stanford University

Edited by Peter Y. Chou

Dr. Paul Davies
Professor of
Natural Philosophy
Australian Center
for Astrobiology,
Macquarie University
Sydney, Australia

Dr. Martin J. Rees
Royal Society
Research Professor
Cambridge University
United Kingdom

Dr. Andrei Linde
Professor of Physics
Department of Physics
Stanford University
Palo Alto, California

In recent years, advances in physics and cosmology have given the "multiverse" idea a plausible scientific basis. Its new lease on life can be traced to the popular theory of inflation, which held that a split second after the Big Bang the universe abruptly jumped in size by a huge factor. In the variant introduced by Andrei Linde, inflation spawns a network of branching "bubble" universes with different laws of physics operating inside of them. It has become fashionable to invoke some species of the multiverse theory to account for the well-known examples of parameter fine-tuning associated with the emergence of life in the observable universe where Earth has its home. The possibility of many universes raises deep scientific, philosophical, and theological questions. How does the multiverse modify our understanding of the ultimate origin of the physical universe in time? Does the cosmos reproduce forever? Can the multiverse theory be made consistent with Occam's razor? Is the theory falsifiable, and if so, how? If our universe, subtle, beautiful, and intelligible as it appears, is just, in Martin Rees's phrase, "one island in the cosmic archipelago," can it really be so special after all? To examine the conjectures that are so dramatically enlarging our cosmic perspective, three scientists will present their views on March 26, 2003, from 8-10 pm.
(sponsored by the John Templeton Foundation -

Professor Savas Dimopoulos of Stanford's Physics Department introduced the three speakers.
Dr. Paul Davies has an asteroid named after him, wrote over 25 scientific & popular books in science, and was awarded the 1995 Templeton Prize for Progress in Religion. Dr. Martin Rees has published over 500 scientific research papers, received nine honorary degrees, and was knighted by Queen Elizabeth in 1992. Dr. Andrei Linde created the inflationary universe paradigm, wrote over 150 papers on particle physics, and was awarded the 2002 Dirac Medal for theoretical physics. This was surely a stellar cast of speakers and the auditorium was packed to capacity despite the Stanford Spring break. I arrived half an hour early as did a friend Rudy Perez and we got good seats, sitting in the second row on the left aisle facing the lecturers. Here are my notes reconstructed with relevant web links. Still to be included are many diagrams sketched during the lecture. These will be added when I find their images in books or on the web.


Dr. Davies spoke first (8:14 pm) and thanked the John Templeton Foundation for sponsoring this symposium at Stanford. He then gave a PowerPoint presentation on his laptop computer (24 slides):
1) Medieval Woodcut showing man's head poking out
    of the earth's sphere to gaze at the stars.
2) Copernicus portrait: his revolution started it all—
    that we're no longer geocentric.
3) Billions of galaxies— many billion of light years away
4) Milky Way— with its billion of galaxies
5) Lesson of Copernicus— Earth is typical; "principle of
    mediocrity" (watchword of science for 400 years).
    Why is the universe mostly empty space?
    We couldn't live in the cold depth of space.
6) Brandon Carter— British cosmologist & astrophysicist
    postulated the Anthropic Principle:
    "the Universe has the conditions we observe because we are here."
7) Provocative Version of Anthropic Principle
8) Playing role of God— change mass of electron a little & universe will collapse
    Physics and cosmology are cunningly fine-tuned for life.
    Or as Fred Hoyle says:"The universe is a put-up job."
9) Strong Anthropic Principle (SAP): "the Universe must have those properties which allow life to
    develop within it at some stage in it's history." Mathematician Martin Gardner has proposed
    CRAP— "Completely Radical Anthropic Principle"
10) When I was a boy in bed, I asked this question:
      "Why are we living now?" (Slide: Milky Way Galaxy).
11) tnow = tuniverse
      (tuniverse / tatomic) = 1040
      When is Now?
12) (e2 / Gmp2) = 1040, where G = Gravitational constant, mp = proton mass
      (tuniverse / tatomic) = 1040
13) Robert Dicke predicted the residual cosmic radiation after the Big Bang. This led Penzias &
      Wilson at Bell Labs to realize that the excess noise temperature in a radio telescope might
      be extraterrestrial. And cosmology dramatically advanced.
14) thumans = t*
      Carbon didn't exist at the creation of the universe.
      Sir James Jeans: "We're the ashes of long-dead stars."
      There can't be any life until a generation of stars has been born & died.
15) Lifetime of stars:
      t* = (hc/Gmp2)tnuclear, where h = Planck's constant
      t* = (e2 / Gmp2)tatomic
      tnow = (e2 / Gmp2)tatomic = 1040
16) Conclusion: No surprise that we are living at the epoch at which the number...(?)
17) Why does space have 3-dimensions? Life will be a struggle if we didn't live in 3-dimensions.
18) Fred Hoyle's great C-O mystery.
      Helium is in primordial matter at the creation of the universe.
      Hoyle predicted spike for chemical reaction of 3 Helium atoms = Carbon atom
      Is this spectral evidence just a cosmic coincidence?
19) Freeman Dyson's di-proton demise:
      2 deuterons collide to form a helium atom.
      Helium universe will not have stable stars like our sun. Also no H2O.
20) Weak nuclear force. Heavy stars implode. Neutrons blast away (explode away).
      Crab Nebulae (1054 AD): disseminate carbon atoms around the universe.
21) Why is gravity so feeble? If any stronger, stars will burn out before life evolved. Universe
      would collapse. Universe must be old, hence big enough to allow time for life to evolve.
22) Ripples at the dawn of time (3 weeks ago photo: NY Times 3/11/2003)
      Incredibly smooth. Heat map showing what the universe looked like 380,000 years
      after the Big Bang (twinkling of an eye compared to 14 billion years age of universe).
23) Gravitation— large scale of the universe will grow.
      Galaxies —> Stars —> Planets —> Humans (Anthropic Principle)
      Catalog of fortuitous things.
24) Why is the universe so suspiciously Bio-friendly?


Dr. Martin Rees was the second speaker (8:35 pm). He proceeded to the projector and said:
"I will now give a "low-tech presentation" (referring to his transparencies compared to Davies'
digitized PowerPoint presentation). Dr. Rees' lecture was only 15 minutes long with only six
transparencies shown. But it was quite elegant and riveting.
1) This is my favorite image (an Ouroborus: snake biting its own tail) where the dimensions
    of the very large (universe) is compared to the very minute (atom), with man exactly
    in between. We're midway between atom and star— the geometric mean between
    atom and star for a man weighing 58 kilograms (The Micro/Nano Universe).
    [Circular Diagram with scale from 10-20 cm (atom) to 1025 cm (universe)]
2) Coincidence
    "Selection" from Ensemble
    The Canadian philosopher John Leslie said: "If you're in front of a
    firing squad of ten, and they all missed shooting you, you'll ask Why?"
3) Here's a diagram of a Mandelbrot set.
    It's a mystery— Why there's a recipe governing our universe?
4) The British philosopher & theologian William Paley (1743-1805)
    postulated the watch & watchmaker (teleological argument). Someone made
    the watch, so there must be a watchmaker. Applied to biology. My favorite
    teacher John Polkinghorne was a physicist who became a clergyman.
    Our universe is more than what we see. (still speculative— "health-warning sign")
    Throw away the "watch & watchmaker" model. If you have a large stocked clothing store,
    you'll find a suit that fits you just right. Our solar system is just one of many
    systems in the universe that have the criteria propitious for life.
    If there is a large stock of universes out there, then what follows?
5) Decision Tree: Question can in principle be answered by a theory that could
    acquire credibility by explanation. 6) How Many Big Bangs?: One or Many
    If One —> No role for anthropic explanations
    If Many —> Variety in the physical laws/constants
    If Variety —> No —> No role for anthropic explanations
    If Variety —> Yes —> By-laws governing in universe should be
                                         typical of anthropically allowed subset.


Dr. Andrei Linde was the third speaker (8:50 pm). He also used the projector but showed 20
transparencies. His talk was more technical than the talks of Davies and Rees. More equations and
diagrams were utilized as he elucidated his inflationary universe models. Whenever he showed
a transparency with lots of equations, he allayed the fears of his audience, "I'm not going to prove
these equations. I'm only going to point to them." This elicited lots of laughter. Linde was the most
humorous of the three speakers despite his more technical talk.

1) Self-Reproducing Inflationary Universe
    Scientific American 271, Nov. 1994, pp. 48-55
2) Standard Big Bang Theory
    (Digram of Size of Universe vs. Time showing Big Bang at origin,
    for closed, flat, and open universes, T = 2.7oK)
    Problems: a) What was before the singularity?
                    b) Why different parts of the universe began expanding simultaneously?
    Closed: surface of a globe (return back home)
    Flat: geometry of a table (square)
    Open: hyperbole (goes out to infinity)
    Whole universe expanded at the moment of the Big Bang.

3) Why space is almost exactly flat?          
lo = 1028 cm.
size if the observable
part of the universe
lp = 10-33 cm.
Planck's length
Why parallel lines do not intersect?
Why there are so many people on the Earth?
1088 particles in the observable part of the universe
4) Why our universe is so homogeneous?
    (dr/r) < 10-4, where r = density

5) What is the origin of galaxies?
    I don't like the word "principle." (referring to Anthropic Principle)
    "Principle" is invoked by people without good ideas. (laughter)
6) Whether the universe could be created differently?
    Why a = (1/137)?
    I have a friend who lived in Apt #137, and believes he's blessed.
    (Diagram of Chaotic inflation from A. Linde, 1983)
7) Simplest Model
    1) Klein-Gordon equation: f" + 3Hf' = -m2f, (where H = Hubble constant)
        (Note: Linde's slide showed .. & . above the first two f. Since I can't reproduce them
        in HTML, I've substituted " & ' instead to represent the 2nd & 1st derivative of f)
    2) Einstein equation (simplified): H2 = (a'/a)2 = (8p/3Mp2) x (m2f2/2)
    Solution for f > Mp [for any V(f) ~ fn]
    a ~ eHt (Inflation Equation)

Typical duration: 10-35
Behaving like an harmonic oscillator
Typical expression of the universe during inflation: 101012 times

10-33 cm x 101012 = 101012 cm
(the first factor is too small & negligent)

10-5 ~ dr/r ~ 10(m/Mp)

8) Universe expanding so fast (Diagram: 3-D sphere showing latitude & longitude)
9) Scalar field fluctuations: (Diagram: Regular sine wave becomes random fluctuations)
    This process produces perturbations
    of density which lead to galaxy
    formation and CMB (cosmic microwave background) anisotropy.
    Our galaxy is the result of quantum fluctuation.
10) The same quantum fluctuation that creates galaxies jump
      very high—then the universe expands exponentially
      and they produce enormous amount of space.
11) Computer Model
      (Diagram: a few non-overlapping curve lines)
12) Black field becomes White field
      (Diagram: Lots of overlapping curve lines).
13) Kandinsky Universe: our universe is a fractal
      (Diagram: Kandinsky's abstract art).
14) Polar universe (Diagram: lots of white snow-ice scene)
15) Computer Model (Diagram: 3-D rectangular box
      with mountain spikes coming out of top)
16) Red diamond shape inside Square (Diagram: 2-D box)
17) Diamond shape becomes colored (Diagram: 2-D box)
18) 2-Dimensional Diamond shape becomes 3-D mountain spikes
19) Inflationary bubble universes after Big-Bang
      (Diagram in Linde's Nov. 1994 Scientific American article)
20) Film: red universe; blue universe; green universe, exploding universe.


Q & A Session: (9:15 pm - 10 pm)

Q: How many universes are out there?
A: Linde: Inflationary universe produces new universes non-stop—
    much larger than 101012.
Q: What is the basis of the inflationary universe?
A: Linde: Inflationary theory explains the microwave radiation & homogeneity.
Q: Is there variation in the fine constant?
A: There is spatial dependence.
Q: What are some strategies to prove or disprove that there is a multiverse?
A: Rees: The balance is shifting to the multiverse.
    Need theory to describe the Big Bang.
A: Davies: There are many versions of the multiverse theory.
    Conjecture of least motives (?)     Universe can have babies— inherit mother's characteristics
    Need to test all the models.
A: Linde: My work was based on (?). We don't know about what's inside black holes.
    Equations of scalar field theory.
Q: (for Dr. Davies) Are we alone?
A: Davies: If you keep shuffling a deck of cards, we'll get everything in order.
    Sooner or later, planet will be created like our earth and generate
    human beings like you. After all, infinity is very big.
Q: (for all three speakers) What would you bet that your multiverse theory is true?
A: Rees: "Some physicist was asked whether he would stake his goldfish, dog, or child
    that his theory was correct, and replied that he would bet his dog.
    I would stake my dog that there's a multiverse out there."
A: Davies: "Me too, at the dog level. The top level is all mathematical."
A: Linde: "I'd bet my life! That's what I've been doing all these years!"
    (The audience burst into loud applause and laughter.)
Q: Is there a God of gods? Can the universe be self-regulating?
A: Davies: I'll be delivering a paper on this topic soon.
A: Linde: On Self-producing universes— if one produces faster,
    it will overtake all the others.
Q: Is the universe collapsing?
A: Davies: (unclear)
A: Linde: Future of universe— may collapse or expand forever.
    Boundary of blue or red (in diagram shown earlier).
Q: What can you say about edges, symmetry, and time between universes?
A: Linde: Water and ice are both H2O—
    same law of physics (water, ice, gas)
    different manifestation of the same law
    fish comes to the ice— can't swim into it.
    There are topologically different universes.
    What we're doing is bizarre enough.
Q: Are universes gravitational bound?
A: Linde: Yes, There are different kinds of dark matter.
A: Rees: Our universe's composition: 4% atoms, 23% dark matter, 73% dark energy.
Lots of big bangs will give different mixtures.
Last Q: Any further thoughts?
A: Davies: This multiverse is the latest big thing.
    I'll have an article in Friday's New York Times (3/28/03)
    (Note: As of 4/10/03, Davies' article has yet appeared.)
A: Rees: The multiverse has implication in theology & peaceful co-existence.
A: Linde: When I was in Russia 13 years ago, there was less freedom than in
    America. Here people will be more open-minded and throw eggs
    at people who talk about the anthropic principle.


The talks & discussions ended at 10 pm. A crowd gathered at some tables in the lobby to purchase and obtain autographs from Dr. Rees and Dr. Davies on many of their popular science books. Prof. Linde was busy answering further questions to around a dozen students on how the multiverse fits well with his inflationary model. Since Linde had left his 20 transparencies on the projector, I took this opportunity to fill some of the gaps in my 11 pages of notes (Several of Linde's transparencies were trimmed off at the top & bottom during his presentation).

After the three lecturers autographed their web pages for me, I heard Dr. Linde speaking to one of his students: "There is you and the universe that's the object of your investigation. But you must also consider a third factor— and that is consciousness! So you need to study all three together. Unfortunately, those who study consciousness, don't know enough physics. I've spoken to several at the Stanford Medical School engaged in brain research, but have not found them helpful." I then suggested to Prof. Linde that he contact some Hua-Yen Buddhists who have seen "tiers and tiers of universes" or Zen Masters who are enlightened. Prof. Linde acknowledged that's the direction he should pursue. When I asked him whether he meditated, he told me, "No. But I've been inspired by the Hindu philosophy and cosmology in my work." I forgot to ask him whether he knew of Joseph Campbell's story to Bill Moyers on the PBS Power of Myth program. Campbell told "Indra's Lesson"— how all the King's men "may count the number of drops in the ocean or number of sands on the beaches, but no one can ever count the number of universes out there."


This article appeared in the April 9, 2003 issue of Stanford Report:
"Beyond 'pi in the sky': Andrei Linde lauds the new era of precision cosmology"

This article appeared in the May 7, 2003 issue of San Diego Union-Tribune:
"Rees' Thesis: Famed cosmologist suggests time may be running out on the human species"

This article appeared in the May 18, 2003 issue of New York Times:
BOOK REVIEW: 'Our Final Hour': Global Warning [Martin Rees]
(By Dennis Overbye, May 18, 2003)

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| Linde: Self-Reproducing Inflationary Universe | Linde: Precision Cosmology | Linde: Cosmic Big Crunch |
| Linde: Inflation & String Cosmology | "What is your question?" | Origin of Universe | Age of Universe |
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© Peter Y. Chou,
P.O. Box 390707, Mountain View, CA 94039
email: (4-10-2003)