The Principle of Mediocrity [cosmological speculations of Alexander Vilenkin]

Edge - The Third Culture ^ | September 15, 2006 | Alexander Vilenkin

[snarks_when_bored]

Intriguing speculative cosmology, to be taken cum grano salis for now...

Some recent articles by Alexander Vilenkin and various co-authors (#23 is written for philosophers of science rather than cosmologists):

The URL for this search is http://xxx.lanl.gov/find/grp_physics/1/au:+Vilenkin_Alexander/0/1/0/all/0/1

Showing results 1 through 25 (of 79 total) for au:vilenkin_alexander

1. astro-ph/0605465 [abs, ps, pdf, other] :

Title: Reionization from cosmic string loops
Authors: Ken D. Olum, Alexander Vilenkin
Comments: 7 pp., RevTeX, no figures
 

2. astro-ph/0605242 [abs, ps, pdf, other] :

Title: The vacuum energy crisis
Authors: Alexander Vilenkin
Comments: 4 pages, no figures; invited "perspective" article in "Science" (4 May 2006)
Journal-ref: Science 312 (2006) 1148-1149
 

3. hep-th/0605015 [abs, ps, pdf, other] :

Title: Eternal observers and bubble abundances in the landscape
Authors: Vitaly Vanchurin, Alexander Vilenkin
Journal-ref: Phys.Rev. D74 (2006) 043520
 

4. hep-th/0602264 [abs, ps, pdf, other] :

Title: Probabilities in the landscape
Authors: Alexander Vilenkin
Comments: Discussion in Sec. IV.A corrected and clarified
 

5. hep-th/0601162 [abs, ps, pdf, other] :

Title: Probabilities in the Bousso-Polchinski multiverse
Authors: Delia Schwartz-Perlov, Alexander Vilenkin
Comments: 21 pages, 7 figures Minor changes made
Journal-ref: JCAP 0606 (2006) 010
 

6. gr-qc/0511159 [abs, ps, pdf, other] :

Title: Scaling of cosmic string loops
Authors: Vitaly Vanchurin, Ken D. Olum, Alexander Vilenkin
Comments: Added discussion of gravitational wave bounds; other minor changes
 

7. hep-th/0509184 [abs, ps, pdf, other] :

Title: Probabilities in the inflationary multiverse
Authors: Jaume Garriga, Delia Schwartz-Perlov, Alexander Vilenkin, Sergei Winitzki
Comments: 18 pages, RevTeX 4, 2 figures. Discussion of the full probability in Sec.VI is sharpened; the conclusions are strengthened. Note added explaining the relation to recent work by Easther, Lim and Martin. Some references added
Journal-ref: JCAP 0601 (2006) 017
 

8. hep-th/0508135 [abs, ps, pdf, other] :

Title: Cosmic strings: progress and problems
Authors: Alexander Vilenkin
Comments: minor changes; added references
 

9. hep-th/0508005 [abs, ps, pdf, other] :

Title: Anthropic prediction for Lambda and the Q catastrophe
Authors: Jaume Garriga, Alexander Vilenkin
Comments: 20 pages, 1 figure
 

10. gr-qc/0501040 [abs, ps, pdf, other] :

Title: Cosmic string scaling in flat space
Authors: Vitaly Vanchurin, Ken Olum, Alexander Vilenkin
Comments: 13 pages,7 figures
Journal-ref: Phys.Rev. D72 (2005) 063514
 

11. hep-th/0410222 [abs, ps, pdf, other] :

Title: Gravitational radiation from cosmic (super)strings: bursts, stochastic background, and observational windows
Authors: Thibault Damour, Alexander Vilenkin
Comments: 16 pages, 6 figures
Journal-ref: Phys.Rev. D71 (2005) 063510
 

12. gr-qc/0409055 [abs, ps, pdf, other] :

Title: Eternal inflation and chaotic terminology
Authors: Alexander Vilenkin
Comments: 5 pages, no figures
 

13. astro-ph/0407586 [abs, ps, pdf, other] :

Title: Anthropic predictions: the case of the cosmological constant
Authors: Alexander Vilenkin
Comments: 14 pages, 1 fugure. Contribution to "Universe or Multiverse", ed. by B.J. Carr, to be published by Cambridge University Press
 

14. astro-ph/0405606 [abs, ps, pdf, other] :

Title: Early reionization by cosmic strings revisited
Authors: Levon Pogosian, Alexander Vilenkin
Comments: 5 pages, a new paragraph added, matches the version accepted to PRD
Journal-ref: Phys.Rev. D70 (2004) 063523
 

15. astro-ph/0404497 [abs, ps, pdf, other] :

Title: Anthropic predictions for vacuum energy and neutrino masses
Authors: Levon Pogosian, Alexander Vilenkin, Max Tegmark
Comments: 9 pages, 4 figures
Journal-ref: JCAP 0407 (2004) 005
 

16. hep-th/0312007 [abs, ps, pdf, other] :

Title: Formation and evolution of cosmic D-strings
Authors: Gia Dvali, Alexander Vilenkin
Comments: Added discussion and references
Journal-ref: JCAP 0403 (2004) 010
 

17. hep-th/0310034 [abs, ps, pdf, other] :

Title: Dark energy equation of state and anthropic selection
Authors: Jaume Garriga, Andrei Linde, Alexander Vilenkin
Comments: 22 pages, 8 figs
Journal-ref: Phys.Rev. D69 (2004) 063521
 

18. hep-th/0309236 [abs, ps, pdf, other] :

Title: Inflating magnetically charged braneworlds
Authors: Inyong Cho (LPT, Orsay), Alexander Vilenkin (Tufts University)
Comments: 35 pages, revtex, 18 eps figures
Journal-ref: Phys.Rev. D69 (2004) 045005
 

19. gr-qc/0305025 [abs, ps, pdf, other] :

Title: Creation of massive particles in a tunneling universe
Authors: Jooyoo Hong, Alexander Vilenkin, Serge Winitzki
Comments: 32 pages, 1 figure
Journal-ref: Phys.Rev. D68 (2003) 023521
 

20. astro-ph/0304536 [abs, ps, pdf, other] :

Title: Anthropic predictions for neutrino masses
Authors: Max Tegmark (MIT), Alexander Vilenkin (Tufts), Levon Pogosian (Tufts)
Comments: Revised to match accepted PRD version. Added references, discussion of very heavy neutrinos, analytic growth factor fit. 9 pages, 4 figs. Color figs and links at this http URL
Journal-ref: Phys.Rev. D71 (2005) 103523
 

21. hep-th/0304219 [abs, ps, pdf, other] :

Title: Gravity of superheavy higher-dimensional global defects
Authors: Inyong Cho (LPT, Orsay), Alexander Vilenkin (Tufts University)
Comments: 19 pages, revtex, 6 eps figures
Journal-ref: Phys.Rev. D68 (2003) 025013
 

22. hep-th/0304043 [abs, ps, pdf, other] :

Title: Cosmic Attractors and Gauge Hierarchy
Authors: Gia Dvali, Alexander Vilenkin
Journal-ref: Phys.Rev. D70 (2004) 063501
 

23. physics/0302071 [abs, ps, pdf, other] :

Title: Philosophical Implications of Inflationary Cosmology
Authors: Joshua Knobe, Ken D. Olum, Alexander Vilenkin
Comments: 25 pages; v2: revised version to appear in British Journal for the Philosophy of Science
Subj-class: Physics and Society; History of Physics
 

24. hep-th/0209217 [abs, ps, pdf, other] :

Title: Solitonic D-branes and brane annihilation
Authors: Gia Dvali, Alexander Vilenkin
Comments: a typo corrected
Journal-ref: Phys.Rev. D67 (2003) 046002
 

25. gr-qc/0204061 [abs, ps, pdf, other] :

Title: Quantum cosmology and eternal inflation
Author: Alexander Vilenkin
Comments: To appear in "The Future of Theoretical Physics and Cosmology", proceedings of the conference in honor of Stephen Hawking's 60'th birthday
 

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[snarks_when_bored]

Plop plop fizz fizz...

[snarks_when_bored]

A slight correction (to the original and to my post):  the passage which reads

An estimate of the number of distinct histories that can unfold in an O-region between the big bang and the present gives 10 to the power 10150 . This number is fantastically huge, but the important point is that the number is finite.

should instead read

An estimate of the number of distinct histories that can unfold in an O-region between the big bang and the present gives 10 to the power 10¹⁵⁰. This number is fantastically huge, but the important point is that the number is finite.

That is, Vilenkin is speaking of the gargantuan number

10¹⁰¹⁵⁰

[grey_whiskers]

Something smells here.

Late at night and I am busy on a political piece, but I will divert a few neurons to this.

I am reminded of the passage in one of Feynman's books about psychology being "cargo-cult science".

At first blush some of this talk seems to be reducing physics to mush--playing with assumed bell-curve distributions of constants which cannot by definition be checked.

What was that about "not falsifiable"?? 95% confidence level is still (technically) not falsified...

The other odd thought popping into my head (ok, alright, one of *many* -- as other Freepers know only too well by now) is this: "God does not play dice with the Universe" by a strange paradox, is true--by this presentation, the Universe itself is itself merely the result of ONE throw of the dice.

And so within any O-region, it appears "God does not play dice" because all we see is one throw.

What happens when two inflationary regions "just happen" to be close enough to encounter or interact with each other?

What are the odds of such a thing happening?

And why didn't *I* get to live in the Universe where Reagan beat Ford for the GOP nomination in 1976 and Carter never happened?

Thanks, Snarks, for the article. Good to the last drop as usual.

Cheers!

[Cacique]

Bumpity Bump

[snarks_when_bored]

Hey, g_w, up late as usual, eh?

What happens when two inflationary regions "just happen" to be close enough to encounter or interact with each other?

What are the odds of such a thing happening?

I've not seen a calculation of those odds, but they're probably quite small. This passage appears relevant:

With inflation, the two competing processes are the decay of the false vacuum and its “reproduction” by rapid expansion of the inflating regions. My calculations, and those of Andrei Linde, show that false-vacuum regions multiply much faster than they decay, and thus their volume grows without bound. At this very moment, some distant parts of the universe are undergoing exponential inflationary expansion. Other regions like ours, where inflation has ended, are also constantly being produced. They form “island universes” in the inflating sea of false vacuum. Because of inflation, the space between the islands rapidly expands, making room for more island universes to form.

Inflation is thus a runaway process that has stopped in our neighborhood, but still continues in other parts of the universe, causing them to expand at a furious rate and constantly spawning new island universes like our own.

However, let me also quote a passage from a different article (I quoted this passage in a post on another thread):

The following paragraph from page 3 of Anthony Aguirre & Steve Gratton, "Inflation Without a Beginning: a null boundary proposal" (2003, PDF format) is somewhat relevant, I think (my red fonting):

"An observer within a bubble can never leave, but will eventually be encountered by an encroaching bubble wall after a typical time τ_coll, where τ_coll^-1 is related to the r-integral of Eq. (5) by some transformation between the bubble observer's proper time τ and cosmic time t. Since this rate depends on t−t₀, a patient and very sturdy observer could in principle discover the global time at which it formed by counting the frequency of incoming bubbles."

From this point of view, islands colliding appears possible...

[Erasmus]

According to the new picture, distant parts of the universe are in the state of explosive, accelerated expansion, called “inflation”. The expansion is so fast that in a tiny fraction of a second a region the size of an atom is blown to dimensions much greater than the entire currently observable universe.

Okay, listen up everybody, important safety tip: Don't cross the beams!

[ModelBreaker]

Bump for further reading.

[Erasmus]

Did you find that out by Googling it?

< }B^)

[snarks_when_bored]

Did you find that out by Googling it?

Nope. I relied on

1. a (vague) memory of Vilenkin's article #23 on the list in post #1:  Philosophical Implications of Inflationary Cosmology" (PDF),
2. a sense for the size of the quantity Vilenkin was trying to quantify, and
3. a sense for the way in which physicists approximate quantities.

But having just checked the article, the number appears near the bottom of page 3...

[Iris7]

From your post,

"According to string theory, the quantities we call "constants of nature" — like Newton's gravitational constant or the electron mass — may in fact be variables that can take a wide spectrum of values. This has been discussed on Edge by Lenny Susskind. Despite some recent fire that string theory has attracted, it remains the best candidate we now have for the fundamental theory of nature."

The following is from http://en.wikipedia.org/wiki/Richard_Feynman

"Shortly before his death, (Richard) Feynman criticized string theory in an interview. These words have been much-quoted by opponents of the string-theoretic direction for particle physics ever since.

'I don't like that they're not calculating anything,' he said. "I don't like that they don't check their ideas. I don't like that for anything that disagrees with an experiment, they cook up an explanation -- a fix-up to say, 'Well, it still might be true.'"

[PatrickHenry]

SciencePing

An elite subset of the Evolution list. See the list's explanation at my freeper homepage. Then FReepmail to be added or dropped.

[phantomworker]

The expansion is caused by a peculiar form of matter, called “false vacuum”, which produces a strong repulsive force.

So that's why some things have been so repulsive lately. LOL /s

Not sure if it's junk science, but an intriguing article. Worth a reread.

[Doctor Stochastic]

95% confidence level is still (technically) not falsified...

But "95%" is an arbitrary number used because an early statistics book had a table of 5% confindence widths. (Things were done by hand then.) The "correct" confidence level is not a mathematical concept but is set by the practical consequences of making one decision or another.

[Doctor Stochastic]

And so within any O-region, it appears "God does not play dice" because all we see is one throw.

But in QM, even when we see over 10**23 throws, things still behave as if at random. There would be experimental consequences were such not the case.

[grey_whiskers]

I get your point--but it was late at night, and my mind was busy with this piece.

Cheers!

[grey_whiskers]

But "95%" is an arbitrary number used because an early statistics book had a table of 5% confindence widths. (Things were done by hand then.) The "correct" confidence level is not a mathematical concept but is set by the practical consequences of making one decision or another.

As a practical ansatz, yes. But if something still has a 5% chance of being true, you haven't falsified it.

Secondly, if we can never tell that any other O-regions exist, then the entire concept of O-regions is "non-falsifiable" empirically.

And that gives me paws pause it what purports to be *science* which is based on systematic observation, experiment, yada yada. You know the drill.

Cheers!

[doc30]

My personal favorite view of such a Mediocracy perspective is quantum mechanical. I really like the idea that all quantum outcomes occur, but we are perceiving the path of one particular series oif outcomes.

[phantomworker]

But in QM, even when we see over 10**23 throws, things still behave as if at random. There would be experimental consequences were such not the case.

Plus, when throwing dice or tossing a coin, there is the memoryless property.

[VadeRetro]

Gads! Never heard of this before. Where have I been?