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Universe or Multiverse? (new w/cosmic natural selection chapter)

  1. Apr 20, 2007 #1

    marcus

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    This is a new book from Cambridge University Press, scheduled to go on sale 30 June 2007, available now for pre-order
    http://www.amazon.com/Universe-Mult...1968818?ie=UTF8&s=books&qid=1177093483&sr=1-1

    The Cambridge.org webpage for the book is here
    http://www.cambridge.org/catalogue/catalogue.asp?isbn=9780521848411

    It gives the table of contents, with prominent chapter-author names such as:

    Lee Smolin
    Alexander Vilenkin
    Frank Wilczek
    Steven Weinberg
    George Ellis
    John Barrow
    Paul Davies
    Stephen Hawking
    James Hartle
    Leonard Susskind
    Max Tegmark
    Andrei Linde

    and more.

    It will probably become a widely read and impactful book. We have already seen and discussed some of the chapters here at PF Beyond forum, as they appeared in preprint form on arxiv.
     
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  3. Apr 20, 2007 #2

    marcus

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    Here's what the Cambridge.org website gives for the book's TOC

    ==quote==
    Part I. Overviews: 1. Introduction and overview Bernard Carr; 2. Living in the multiverse Steven Weinberg; 3. Enlightenment, knowledge, ignorance, temptation Frank Wilczek; Part II. Cosmology and Astrophysics: 4. Cosmology and the multiverse Martin J. Rees; 5. The anthropic principle revisited Bernard Carr; 6. Cosmology from the top down S. W. Hawking; 7. The multiverse hierarchy Max Tegmark; 8. The inflationary universe Andrei Linde; 9. A model of anthropic reasoning addressing the dark to ordinary matter coincidence Frank Wilczek; 10. Anthropic predictions: the case of the cosmological constant Alexander Vilenkin; 11. The definition and classification of universes James D. Bjorken; 12. M/string theory and anthropic reasoning Renata Kallosh; 13. The anthropic principle, dark energy and the LHC Savas Dimopoulos and Scott Thomas; Part III. Particle Physics and Quantum Theory: 14. Quarks, electrons and atoms in closely related universes Craig J. Hogan; 15. The fine-tuning problems of particle physics and anthropic mechanisms John F. Donoghue; 16. The anthropic landscape of string theory Leonard Susskind; 17. Cosmology and the many-worlds interpretation of quantum mechanics V. F. Mukhanov; 18. Anthropic reasoning and quantum cosmology James. B. Hartle; 19. Micro-anthropic principle for quantum theory Brandon Carter; Part IV. More General Philosophical Issues: 20. Scientific alternatives to the anthropic principle Lee Smolin; 21. Making predictions in a multiverse: conundrums, dangers, coincidences Anthony Aguirre; 22. Multiverses: description, uniqueness and testing George Ellis; 23. Predictions and tests of multiverse theories Don N. Page; 24. Observation selection theory and cosmological fine-tuning Nick Bostrom; 25. Are anthropic arguments, involving multiverses and beyond, legitimate? William R. Stoeger; 26. The multiverse hypothesis: a theistic perspective Robin Collins; 27. Living in a simulated universe John D. Barrow; 28. Universes galore: where will it all end? Paul Davies.
    ==endquote==

    Several of the exact chapters can be found on arxiv by searching under author name and title keywords. In other cases, if the exact essay is not available there will be SIMILAR articles on the same topics, with slightly different titles, by the same author.

    Probably the most important chapter, IMO, is one that is already available online. The book will give it additional visibility.

    http://arxiv.org/abs/hep-th/0407213
    Scientific alternatives to the anthropic principle
    Lee Smolin
    Contribution to "Universe or Multiverse", ed. by Bernard Carr et. al., to be published by Cambridge University Press. Some references and clarifications added

    "It is explained in detail why the Anthropic Principle (AP) cannot yield any falsifiable predictions, and therefore cannot be a part of science. Cases which have been claimed as successful predictions from the AP are shown to be not that. Either they are uncontroversial applications of selection principles in one universe (as in Dicke's argument), or the predictions made do not actually logically depend on any assumption about life or intelligence, but instead depend only on arguments from observed facts (as in the case of arguments by Hoyle and Weinberg). The Principle of Mediocrity is also examined and shown to be unreliable, as arguments for factually true conclusions can easily be modified to lead to false conclusions by reasonable changes in the specification of the ensemble in which we are assumed to be typical.
    We show however that it is still possible to make falsifiable predictions from theories of multiverses, if the ensemble predicted has certain properties specified here. An example of such a falsifiable multiverse theory is cosmological natural selection. It is reviewed here and it is argued that the theory remains unfalsified. But it is very vulnerable to falsification by current observations, which shows that it is a scientific theory.
    The consequences for recent discussions of the AP in the context of string theory are discussed."
     
    Last edited: Apr 20, 2007
  4. Apr 20, 2007 #3

    marcus

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    CNS hypothesis

    The new book's "Scientific Alternatives" chapter contains the
    CNS hypothesis

    which challenges us to find some fundamental physical parameter which is not already well-adapted for the formation of astrophysical black holes and whose adjustment would make them more abundant.

    The physical parameter should be a dimensionless number (like a mass ratio or a coupling constant) input to the standard models of matter and cosmology.

    By way of illustration, Smolin has calculated that if an astronomer happened to find a neutron star for which he could reliably determine the mass was greater than 1.7 solar, this would show that a certain number--a quark mass ratio--could be adjusted to make neutron stars more apt to collapse and produce black holes. It would be possible to "improve" the parameter, making black holes more abundant, and this would refute the CNS hypothesis.

    The CNS hypothethis is that all fundamental parameters are already at local optimum for astrophysical black hole formation, so it can can be refuted by finding a small adjustment of ANY parameter which physicists reason would conduce to more black holes. So the hypothesis appears highly exposed to possible falsification and it is remarkable that it has not been falsified as yet.

    In particular so far no neutron star has been reliably shown more massive than 1.7 solar (there is a case but the uncertainty is large enough to make it dubious). However many neutron stars have been discovered and a number of their masses determined. So the CNS hypothesis continues to survive testing and remains so-far unrefuted.

    In 2006 Vilenkin tried to refute it on other grounds, involving another numerical parameter, but seems to have failed.

    This CNS hypothesis represents a very interesting outstanding challenge. If it did turn out that the input parameters to our basic models are all well-adapted to black hole formation, this would be remarkable and would call for explanation.

    The CNS hypothesis is also a falsifiable prediction of a certain branching cosmology concept which goes back to John Archibald Wheeler.
    It is probably the only clearcut falsifiable prediction made so far by any of the "multiverse" concepts.

    This is why it is of key importance in the context of this new book.
     
    Last edited: Apr 20, 2007
  5. Apr 20, 2007 #4

    cristo

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    Thanks for the link, marcus. Bernard Carr mentioned to me in an interview that this book was coming out at some point later in the year; so it's good to have a peek! Whilst I probably won't understand much of it, it seems like some of the chapters will be an interesting read! So, thanks again for the link!
     
  6. Apr 20, 2007 #5
    Here is a list of the arXiv preprint articles mentioned by Marcus.
     
  7. Apr 20, 2007 #6

    marcus

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    Thanks to you both!
    Jennifer that is a handy bit of web-gathering which was kind of you to do. It makes the thread considerably more useful. (aren't search engines great!)
    Cristo, it is good to know you are in direct touch with the book's editor Bernard Carr. (math and astronomy at QMUL) I hope to be favored with some firsthand bits of news of astronomical goings-on at University of London.
     
    Last edited: Apr 20, 2007
  8. Apr 20, 2007 #7

    cristo

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    Well, I'm not there yet; but as of September then yes, I shall post anything that may be of interest!
     
  9. Jun 13, 2007 #8

    marcus

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    Universe or Multiverse? goes on sale this month and it is listed (available for pre-order) by both US and UK amazon

    I for one do not intend to buy it, the book is expensive and has many chapters by authors whose multi-speculations I'm not interested in. But I'm interested in how the book sells and how it is reviewed.

    At present the US and UK salesranks are both right around one million.

    http://www.amazon.co.uk/Universe-Multiverse-Bernard-Carr/dp/0521848415

    http://www.amazon.com/Universe-Multiverse-Bernard-Carr/dp/0521848415

    The book is intended, in part, to fuel controversy---it has essays both for and against introducing the Anthropic Principle into otherwise scientific discourse.
    Both favorable and critical of multiverse-visions related to Eternal Inflation Scenarios and to the near-infinity of string theories (the "Landscape of String Vacua").

    It is also intended, I believe, to help FRAME the Multi-Uni controversy productively by getting different points of view clearly laid out.

    If the salesrank would drop from 1,000,000 down to a few thousand, then I might try to get ahold of a copy just to see what it was that other people were reading.

    ================
    BTW no disrespect intended to Bernard Carr. I have a high regard for him and think he did a real service getting this book together.
    And Carr might turn out to be Cristo's thesis advisor or favorite professor at Queen Mary London, so critics should remember that and control themselves :smile:
    ================

    another BTW: Sean Carroll has a set of slides to a talk where the version of cosmology is oddly similar to Smolin CNS----he explicitly assumes Quantum Gravity will smooth out the relevant classic Gen Rel singularities and he has baby universes pinching off from blackholes and growing up to become "universes like ours". In other words a reproductive picture.

    http://cosmicvariance.com/2007/06/11/latest-declamations-about-the-arrow-of-time/

    http://preposterousuniverse.com/talks/time-colloq-07/

    Sean Carroll strikes me as a bit like a weathervane, so this may be a sign that CNS-like reproductive cosmology schemes are gaining favor.
    ================
    UPDATE: the book's US amazon salesrank is still around 1,000,000
    but in contrast to that, just in the past 20 hours its UK salesrank has jumped to 57,000 or so.
     
    Last edited: Jun 14, 2007
  10. Jun 16, 2007 #9
    I read "Life of the cosmos" from Smolin. I find the CNS principle at least more attractive than the Anthropic principle (which I don't find attractive at all.)
    However I have a maybe stupid thought:
    In the CNS it seems, that the number of black holes in maximized.
    This means, a single black hole will be smaller.
    Nobody knows of course what happens inside a black holes, but I find it somehow strange to assume, that a tiny little black hole of one gramm can produce the same kind of baby universe as one say as big as our milky way.
    Does anybody know, why the size of the black holes produced is, as far as I can tell, Smolin not worth a single sentence in his book?
     
  11. Jun 16, 2007 #10

    marcus

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    remember that the CNS hypothesis is that the fundamental constants are at a LOCAL maximum, not a global maximum.

    the hypothesis is that you can't find a small change to the parameters that would make holes more abundant

    I don't see why that follows, Micha. Can't the total amount of available material vary? Also the fundamental parameters would influence the probability that a given bit of material ends up in a black hole, rather than in a dead dwarf or neutron star. At least in some scenarios, I'd say. So I don't think more implies smaller.

    the only processes to make BH that I see produce BH of stellar mass----essentially two or more solar masses. the idea that there are processes producing gram-size BH is possible, but speculative.

    there has even been some Quantum Gravity research that found a minimum size for BH. I am skeptical about whether significant numbers of very small exist. but that is a judgement call.

    maybe you see a possible way to make a small, evolutionary, change in the standard model parameters that could cause big increase in numbers of tiny holes. I don't see it.

    =================

    I think we are really talking about how could a STELLAR MASS hole produce a universe. How can one account for the enormous increase in mass?

    Inflation.

    Inflation greatly increases the total amount of matter in the universe.

    A certain amount of inflation is generic in LQC models---it happens naturally without having to put an "inflaton" scalar field in "by hand".

    there is a paper by Ganashyam Date about this---look for G Date author with the arxiv search engine if you want. Also Bojowald has some papers about naturalness of inflation in LQC.
     
    Last edited: Jun 16, 2007
  12. Jun 17, 2007 #11
    Think SMBH's as Einstein-Rosen Bridges:biggrin:

    They have Event Horizons 'covering' the singularities:biggrin:
     
  13. Jun 17, 2007 #12

    Fra

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    Scientific method

    I think these evolutionary topics is an interesting focus point.

    It seems many people maintan som Poppian ideals that evolution takes place be rejecting falsified theories. And for that evolution or scientific process to work, a theory must be principally falsifiable to start with.

    When you consider that, it seems to be almost obvious, and hard to argue with. But I think that the question asked to which the poppian ideal is the answer to, can be improved. And the improvement is more in line with a deeper evolutionary thinking.

    Popper's idea seems to be that we come up with a theory, and continue to test it, until it's proven wrong, then we replace it. But the popper framwork doesn't seem to make explicit, a prediction of the new theory. In my opinon his is the non-trivial step, where the focus should be, isn't it?

    So it seems what we should be looking for is a theory, that suggest how we should update theory_n to theory_(n+1) in the event of falsification.

    Again, how would one falsify such a "theory of theories"? It seems to me the answer is that the winner lives/grows and the looser dies/shrinks. A true evolutionary ideal.

    So, I don't see how falsifibility is a reasonably sufficient condition. I would also like to see a defined response plan, to a falsification event, so that the theory will live/evolve on, also in hard "times".

    /Fredrik
     
  14. Jun 17, 2007 #13
    You are probably right. In an open universe, some material would never go into a black hole. In a closed universe with a big crunch, eventually all material will go into a black hole again.


    I did not want to advocate for tiny black holes. Just trying to use them as an extreme example to make my point clear.


    Exactly. This is my concern. Expecting energy conservation to hold would probably be too naive, but a whole new universe from a one stellar mass black hole is somehow hard to swallow. Marcus, I will look up the papers. But do you know of any intuitive argument how inflation is able to do this? And what about entropy then? A bing bang like singularity and a black hole should differ in the entropy by many, many orders of magnitude.
     
  15. Jun 17, 2007 #14
    The idea of a multiverse looks interesting but the universe is starting to look like an infinite Russian nested doll...isn't it?
     
  16. Jun 17, 2007 #15

    Chronos

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    An interesting point, jonegil. The matryoshka dolls analogy is a good one. At some point, as Hawking noted, our universe will refuse to downsize. Assuming the planck temperature is the upper limit seems reasonable.
     
  17. Jun 23, 2007 #16

    marcus

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    book now on sale in UK, appears in US next month

    The Universe or Multiverse? collection of different people's viewpoints has gone on sale in UK
    and when I looked today the amazon salesrank was 32,293

    which is pretty good for a serious book IMO
    http://www.amazon.com/Universe-Mult...1968818?ie=UTF8&s=books&qid=1177093483&sr=1-1
    http://www.cambridge.org/catalogue/catalogue.asp?isbn=9780521848411

    the book presents essays from all sides of a complicated controversy so there is no single message or central personality to be interviewed by BBC and take part in public debates. So it would be hard to sell such a book.

    But a remarkable list of authors contributed. Maybe if one could stage a brawl between seven or eight of them---including Nobel Laureates.

    Here's a short sample I gave earlier, of some of the authors who contributed chapters

    Lee Smolin
    Alexander Vilenkin
    Frank Wilczek
    Steven Weinberg
    George Ellis
    John Barrow
    Paul Davies
    Stephen Hawking
    James Hartle
    Leonard Susskind
    Max Tegmark
    Andrei Linde
     
    Last edited: Jun 23, 2007
  18. Jun 24, 2007 #17
    Hi Marcus,

    1 - The cover art of ‘Universe or Multiverse?’ sure looks like a Calabi-Yau Manifold [CYM].

    One might even argue that this art is a looping string, stringing loop or STROOP?

    A 3D-complex CYM may even have innate electromagnetism and function as a twistfoam [as opposed to a spinfoam]?

    The US available date is 31 July.

    http://amazon.com/s/ref=nb_ss_gw/10...=search-alias=aps&field-keywords=bernard+carr


    2 - It is good to see physics beginning to list almost all the possibilities, sort of like a ‘differential diagnosis’ rather the usual “I’m right, you’re wrong” argument so often used in the conflict among variants of LQG and String theories.

    The difficulty lies in assigning the probable likelihood of these different possibilities.

    ‘Ito Calulus’ or other future ‘Gauss Prize’ recipients “for Applications of Mathematics” may be of assistance. This may even include mathematical game theory if energy economics is found to have a role.

    http://www.mathunion.org/medals/2006/GaussPrize2006-Ito.pdf


    3 - Assistance may also be warranted from ‘Rolf Nevanlinna Prize‘ recipients for “Mathematical Aspects of Information Sciences”. Particle physics and cosmology do seem to contain information that is likely transformed rather than simply lost or retained intact.

    http://www.mathunion.org/General/Prizes/Nevanlinna/index.html


    4 - Have you reviewed ‘Morse theory‘. Apparently Maxwell as well as Witten thought this might be useful for “analyzing the topology of a manifold by studying differentiable functions on that manifold” as “anharmonic oscillators“. Morse theory has aspects consistent with mathematical game theory.

    http://en.wikipedia.org/wiki/Morse_theory
     
  19. Jun 24, 2007 #18
    I'd thought of blackholes to mini whiteholes leading to creation of space..ie black holes convert matter to space in another universe or possibly this same one but in a different place.
     
  20. Jun 24, 2007 #19

    marcus

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    Good. You got a corner of that idea on your own! It goes back to J. A. Wheeler in the 1970s I think. Not sure about that. doesnt necessarily involve the "white hole" idea-----the versions I heard never involved mention of white hole.

    Just a straightforward collapse to BH our universe and spacetime continuing in a big bang from the pit of the BH. Inflation takes care of supplying the matter and energy for the new section of universe.

    The special thing that Smolin did in around 1994 was to think of a version of the idea that you could TEST by conventional astronomical means.

    If you want to develop a theoretical idea, the key is to make it FALSIFIABLE, so that it makes some prediction which a future experiment or astronomical observation could negate. then you are doing empirical science.

    Several people including yourself, apparently, and including J.A. Wheeler have thought of versions of this idea. So far only Smolin managed to come up with a version which can be DISPROVED----and therefore is empirically testable.

    His version is a reproductive cosmology in which the physical characteristics of the universe evolve so as to make universes richer in black holes----because universes that make lots of babies come to dominate the population.

    Therefore if we are in a typical example, the physical characteristics of our universe should appear to be "fine-tuned" (actually evolutionarily adapted) to produce lots of babies.

    This leads to certain physical/astrophysical predictions which can be tested. If the contrary is observed, then Smolin's version fails the test and is shot down.
    If not, then it passes the test and gains credit.

    I like that version because of the testability.
     
  21. Jun 25, 2007 #20
    thats a sweet idea...

    ...my whiteholes though appear at plancksize in the nuclei of subatomic particles and force space out at that level

    so yeah, i don't know how you'd look into that to test it, maybe you could recalibrate the LHC ???

    :biggrin:
     
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