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Question on Smolin's theory on Black Holes and new Universes

  1. Nov 30, 2014 #1
    Smolin has a theory that black holes in our Universe result in new Universes. He says Universes that are capable of creating black holes get to produce more Universes etc.

    http://www.space.com/21335-black-holes-time-universe-creation.html

    I was reminded of Smolin's ideas by this recent article:

    http://www.mnn.com/earth-matters/sp...ged-from-a-black-hole-in-a-higher-dimensional

    So I was wondering is Smolin's theory regarding the importance of black holes becoming more mainstream? Presumably it could never be proved? At least Black Holes seem to be a partition between our U and somewhere else.
     
    Last edited: Nov 30, 2014
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  3. Nov 30, 2014 #2

    Drakkith

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    I'd say it's about as mainstream as Santa powering his sleigh with depleted anti-uranium. o0)

    But seriously, I'd probably look at it as simply an interesting but unlikely possibility.
     
  4. Nov 30, 2014 #3

    Doug Huffman

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    Fitness landscapes and anthropic cosmologies are common topics not only at the Perimeter Institute where Smolin is associated, but also of Smolin's foil, Leonard Susskind at Stanford U. with his anthropic string theory landscape.

    Smolin predicted a maximum mass of neutron stars that has been verified but not yet Popper falsified. How that bears on your question of his credibility is quite up to the observer.

    As to 'partitions', Susskind defends and explains the mulitverse, that he calls Megaverse, quite well, enough that I understand it.
     
  5. Nov 30, 2014 #4
    Thanks Doug, I didn't know much of that. Coincidentally I think I also independently thought of the words partition and megaverse to describe the same ideas as Susskind.

    Thanks Drakkith, I was mainly trying to find out how likely other Cosmologists thought this is, compared to say branes or string theory or wormholes and other theories. If anything in our U can create a partition and gateway to somewhere else then from what I understand it a BH would have the best chance.
     
  6. Nov 30, 2014 #5

    Chronos

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    In Smolin's original cosmic natural selection hypothesis, circa 1992, he predicted a maximum neutron star mass of about 1.6 solar. While larger mass candidates were discovered over the years, the error bars remained large enough to accommodate the hypothesis until 2010; http://arxiv.org/abs/1010.5788, Shapiro delay measurement of a two solar mass neutron star. Smolin hedged his bet in 2004 to 2.5 solar masses; http://www.nat.vu.nl/~wimu/Varying-Constants-Papers/Smolin-Physica-2004.pdf, Cosmological natural selection as the explanation for the complexity of the universe. As far as I know he still holds to that prediction. At least in my mind, the original conjecture has been refuted.
     
  7. Nov 30, 2014 #6

    marcus

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    Doug, your mentioning fitness landscapes is the key thing. What distinguishes Smolin's idea is not that gravitational collapse may rebound "out the bottom" and create a new spacetime region (a form of "reproduction" :w )
    A number of physicists have proposed/considered the idea that (at least above some critical mass) a black hole collapse may result in a new spacetime region. At the present state of things we can't KNOW what happens instead of the formation of a singularity but it's not uncommon for quite mainstream people to doubt the formation of a classical singularity and to consider quantum gravity effects may cause a rebound (either back in our faces or out the back door, so to speak.)

    Your point about fitness landscape highlights what was original about Smolin's 1992 proposal. He suggested that reproductive fitness could explain some of the values of physical constants (ratios of masses of various particles, ratios of forces to each other, the constants in the laws of physics).
    If the constants could slightly MUTATE when a new region issued from collapse, then the universe would consist predominantly of regions where the laws and constants of physics were favorable for reproduction

    And so if one assumed we find ourselves in a fairly typical part of the universe we should be able to PREDICT some of the constants of the laws of physics by figuring out which values of the constants e.g. favored stable atoms of carbon and oxygen (because their molecules help gas clouds condense to form stars by radiating away heat, and so allow more stars and eventually more massive collapses.)
    The originality of the 1992 "Cosmic Natural Selection" (CNS) proposal was that it was NON-ANTHROPIC. It had nothing directly to do with life or humans or observers etc etc. It offered to explain features of the Standard Models of particle physics and of cosmology by reproductive fitness.
    The values of the constants are such as would place our region on a hilltop in the reproductive fitness landscape. A local maximum for the birthrate of viable offspring regions.

    I would say that collapse leading to rebound is a MAINSTREAM idea, and you would find 100s of researchers willing to take that seriously as a reasonable outcome of gravitational collapse. It is one of several ideas of what might actually happen (instead of formation of a "singularity", which is more a symptom of failure or breakdown of the classical theory). It is important not to confuse this with Smolin's idea. His idea was, assuming you do get new regions budding off from gravitational collapse, that the physical constants might evolve and might thereby be predictable.

    That's a lot bolder as a proposal. The best one can say is that it does seem to be falsifiable, as you indicate. One can try to find physics constants which, if significantly varied, like 5 or 10 percent (?) would this degrade the ability of clouds to radiate waste heat and massive stars to form and eventually collapse? Or at least would small variations like that NOT cause those abilities to increase? (that would be really bad for the idea!)
    There should be a lot of bold risky proposals for why the laws of nature are what they are, and not something different. I expect we will be seeing more such proposed as physics progresses and asks deeper questions. Offering possible explanations for the laws and constants could become increasingly part of the mainstream. We'll see :)
     
    Last edited: Nov 30, 2014
  8. Nov 30, 2014 #7

    marcus

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    BTW That new book The Singular Universe that Smolin coauthored with Roberto Unger seems to be on the point of release. Amazon is taking advance orders:
    https://www.amazon.com/The-Singular-Universe-Reality-Time/dp/1107074061
    I looked up "cosmological natural selection" in the book's index and it says that is discussed on pages
    454-460, 464, 499, 525, and 527-528.

    The book is published by Cambridge University Press. I'll check the Cambridge UP website to see if there is more information on it.
    http://www.cambridge.org/us/academi...-and-reality-time-proposal-natural-philosophy

    The book has nearly 600 pages (several ideas are discussed about how laws of nature can have evolved, obviously it is not solely about CNS). CUP is pricing it at around $30, which kind of surprised me. They must expect it to appeal to a wider audience than just academics.

    the Cambridge Press website lets you browse the book, TOC, sample chapter selections, index etc.
     
    Last edited by a moderator: May 7, 2017
  9. Nov 30, 2014 #8
    Thanks Marcus for clarifying the distinction, I was not aware of that. Both the collapse leading to rebound (to a new U?) and Smolin's theory have a certain elegance, not that that means anything of course.

    I would be very interested in learning how well this, and other speculative theories are accepted. Perhaps some kind of a ratings system amongst Cosmologists would help part timers know which one theories to take more seriously?
     
    Last edited: Nov 30, 2014
  10. Nov 30, 2014 #9

    marcus

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    If I were a professional cosmologist, doing research, I would take those theories seriously which were relevant to my specialty, and had not been disproven. If I was not studying the very start of expansion and how we can learn about it, I would not bother to make a serious evaluation.
    I would not be interested in answering the "big questions" I would focus on ideas that had a bearing on my research specialty.

    So, for researchers with a legitimate interest in bounce cosmology or in NONSINGULAR cosmology generally (where there is something besides a "singularity" at the start of expansion) there are special sessions at the international conferences where they can get together and present their papers and discuss, and there are REVIEW articles that survey the different models and approaches to modeling the start of expansion (and the conditions preceding and around that).

    I don't think I can give you any guidance about what YOU PERSONALLY should "take seriously" or not. If you were doing research in some type of bounce cosmology, you could publish in peer review professional journals on the same basis as other mainstream research--i.e if the quality met standards.
    You could deliver your papers at mainstream international conferences, at the appropriate parallel sessions, on the same basis as other--i.e if your research was up to standard. You could find other bounce cosmology specialists to argue with, about your various different approaches, and so on.

    But if you are not already involved I don't see any basis on which I could advise you. Why should anybody be more interested in this line of cosmology research than in, say inflation theories, or CmB interpretation, or galaxy-redshift counts as a key to structure, or dark matter distribution, or galaxy formation(!!!), or ages of star populations,...???

    Personally I find the mainstream research classified as "quantum cosmology" (which for the most part is quantum bounce cosmology) intensely fascinating--so I follow it with fairly close attention even though I have no career interest (I'm retired.)
    I'll get you a link to the QC papers since 2009, ranked by number of citation (a rough measure of importance in the QC category) to satisfy any curiosity, you can read the titles of the papers and sample abstracts here and there if you wish.
    But I cannot advise you. It would be extremely pretentious of someone to say "do be interested" or "don't be interested", fatuous even.
    You are or you aren't. If someone is, and is able to read the technical literature, I can suggest papers.

    I'll get that QC link. It is to the Stanford-SLAC research data base, using keyword "quantum cosmology"
    This is "quantum cosmology" since 2009, Inspire search:
    http://inspirehep.net/search?ln=en&ln=en&p= "quantum cosmology" and NOT d 1900->2008&of=hb&action_search=Search&sf=&so=d&rm=citation&rg=25&sc=0 (750 found as of 30 Nov 2014)

    You can see the QC research output is on the order of 10 papers per month, roughly 120 per year.
    I checked and roughly half are in the Loop QG approach and the other half are in various other approaches to quantum gravity and quantum cosmology. And I see no compelling reason to take such details (of rates and percentages) seriously as if they indicated something with longterm validity or relevance. Before year 2000 the Loop QG annual share was roughly zero, now it is 50%, other approaches percentage shares have changed as well during that time.. Research emphasis changes.
    Researcher interest shifts.
     
    Last edited: Dec 1, 2014
  11. Nov 30, 2014 #10

    marcus

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    Still, that said, if you want to look at a review article about bounce cosmologies that survey the rebound ("no-singularity") models of the start of expansion, tell me. I'll try to find something along those lines. Maybe other people will help find a "bounce cosmology" review article, or a "non-singular" cosmology review. I have a dim memory of seeing one by a Brazilian physicist named Pereira, a few years back. Not sure. It was a while ago. Something is bound to turn up if you really want to find one. :w
     
  12. Dec 1, 2014 #11

    Chronos

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    Yes, that is an interesting question. The consensus is often viewed as the latest SciAm or Nature article by an authority deemed notable by the popular press.
     
  13. Dec 1, 2014 #12

    marcus

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    It's so important to distinguish between the (fairly widespread) idea of gravitational rebound at extreme energy density and the (rather exceptional) idea of the evolution of natural laws and constants by reproductive success. In any case one's subjective "belief" or opinion about "likelihood" is not so important, what counts is the empirical evidence that eventually piles up and what gives the simplest best fit.
    To illustrate the ongoing research on quantum bounce cosmology, here's a paper by some physicists at University of Barcelona that just appeared last week:

    http://arxiv.org/abs/arXiv:1411.7611
    Viability of the Matter Bounce Scenario
    Jaume de Haro, Jaume Amorós
    (Submitted on 27 Nov 2014)
    It is shown that teleparallel F( T ) theories of gravity combined with Loop Quantum Cosmology support a Matter Bounce Scenario which is an alternative to the inflation scenario in the Big Bang paradigm. It is checked that these bouncing models provide theoretical data that fits well with the current observational data, allowing the viability of the Matter Bounce Scenario.
    9 pages. Communication to the ERE2014.

    To repeat this is to know about, one of the competing types of bounce model, not to believe in :)
    this type of bounce was pioneered by a prominent former string theorist, Robert Brandenberger (McGill U. , Montreal), who has gotten over into bounce cosmology. You can see a bunch of references to him and other Montreal people in the above paper's bibliography.
     
    Last edited: Dec 1, 2014
  14. Dec 1, 2014 #13
    Thanks Marcus. Does black hole collapse and then bounce mean an all new Universe with our Universe continuing on? Or is bounce the scenario that I remember from decades ago where our whole universe reverses and collapses to a singularity creating a whole new Universe?
     
    Last edited: Dec 1, 2014
  15. Dec 1, 2014 #14

    marcus

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    At this stage of the game the researchers are developing different models of collapse (BH or entire universe collapse) that do different things. Our role is not to believe this or that model but to be interested in them enough to learn a little bit about the various ones. Rovelli has been working on a model of BH that does not make a new region of spacetime. The bounce causes a gammaray burst right here in this universe, somewhat like a supernova explosion. It is greatly delayed by the gravitational time dilation in the intense gravity at the core. That is interesting because we might SEE such explosions, from BH that formed a long time ago and have finally reached the bursting point. It is not likely any such things, if they exist, are near enough to hurt us.

    Many other LQG researchers have worked on a BH collapse model "with our universe continuing on" like you said, where the bounce creates a new spacetime region.

    BH collapse and "Big Crunch" are two different trains of thought. You mention recalling discussion of how an entire universe might stop expanding and slowly begin to contract and eventually collapse. That is theoretically possible---it is different from a BH collapse (which is localized)---and such a global collapse may have resulted in a bounce and been the beginning of our expanding universe. That is an important feature of Loop Quantum Cosmology (Lqc) and there are hundreds of papers by many people studying that. Ooops, wife calling, have to go help with supper! Back later
     
  16. Dec 2, 2014 #15

    marcus

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    Tanelorn I guess the answer to both your questions is YES. For a substantial number of researchers (I don't know exactly how many) BH collapse does mean our universe continues on, we just see a conventional BH horizon (with maybe a little Hawking radiation---a slow evaporation) but inside, at the center, instead of a singularity there is a bounce creating a new expanding region of spacetime. There are variations on that theme.

    And your second question was really about whole universe collapse, not BH collapse. There too, the formation of a singularity is avoided by quantum effects which kick in at extreme density (according to Loop QG, and ,it seems, some other versions of QG) causing gravity to repel briefly at that extremely high density, so there's a bounce and the universe re-expands. So your second question is basically Yes also. You heard right. Some people might not want to call the expanding phase "a whole new universe". You could think of it as the same universe, first in a contracting phase and then expanding.
    In between a bounce at extremely high density, in which it is possible that all structure, all traces of the past, are wiped out.

    It has been a rather intense day and I'm kind of wiped out myself. I'll return to this tomorrow and hope to say things more clearly.
     
  17. Dec 2, 2014 #16

    Doug Huffman

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    I am about 50 pages into 'Singular Universe' and the concept of other than one universe is disparaged.
     
  18. Dec 2, 2014 #17
    Thanks Marcus. I was mainly trying to understand the term bounce. From what I now understand bounce is the creation of a new Universe from either the creation of a Black Hole, or the reversal and collapse of our entire Universe into a black hole. Why do they call this bounce?
     
  19. Dec 2, 2014 #18

    marcus

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    That's a good question because it reveals an obstacle to understanding which could be bothering other people as well.
    Bounce refers to a phenomenon that people discovered when they quantized GR and were surprised to see that the quantum correction terms that came in with quantizing the classical theory of gravity and became dominant at extreme energy density and short distance actually counteracted the attraction and made gravity repel.

    It is somewhat analogous to the "nature resists being pinned down" Heisenberg Uncertainty Principle which says if you try to confine a particle to an extremely narrow range of position it will acquire a wide range of momentum. If you try to pin it down as to position it will be wildly zooming this way and that way. And if you try to be extremely certain about its momentum you start losing your grip on its whereabouts.

    The bounce is kind of a HUP applied to gravitational collapse. But note that people have COMPETING PROPOSALS for quantizing gravity at extremely high density. However there one can see a kind of convergence among several different models. Brandenburger's "matter bounce", and the Loop approach, and various offshoots I can't keep track of, various "modified gravity" or "teleparallel" models show the same general feature: in collapse as density gets very high at some point geometry resists being infinitely pinned down and gravity repels.

    This doesn't mean that it has to create a new region of spacetime! In many models it does do that, but in Rovelli's treatment a black hole collapse blows up! You know about gravitational time-slowing. To an outsider the explosion may be delayed by billions of years so we don't see it. The collapse just looks like a conventional classical black hole. But if you could live long enough to witness it, it would eventually explode in our universe (blow up "in your face", so to speak). That too is a bounce so the quantum GR bounce does not imply creation of a new spacetime region, not in every model.

    Rovelli has written papers about the cosmological bounce, where the universe is in an expanding phase which was preceded by a contracting phase.
    There seems to be no contradiction. If our universe stays around, then according to his proposal a BH (local) collapse bounces and blows up in our universe (like a supernova or GRB). If our universe sometime in future enters contracting phase and does not stay around, then it is a global or total collapse, which bounces and goes from contracting phase to expanding phase.

    AFAIK a BH model bounce can either create an explosion (in our distant future) or a new region. I'm interested in learning more about either type of model. So "bounce" per se doesn't specify one or the other.
    On the other hand, when you look at cosmology, there's a remarkable convergence: an increasing number of researchers have gotten interested in models where you can work back in time and find that our start of expansion is actually a rebound from an previous contracting phase of the same universe.
     
    Last edited: Dec 3, 2014
  20. Dec 2, 2014 #19

    marcus

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    I'm delighted you got such an early copy! Last time I looked it had not come on the market yet and both Amazon and the publisher (cambridge university press) were taking "advance orders". Did you qualify for a review copy? You may have other reviews of other books online, in that case. :w

    In case anyone hasn't browsed the book online yet, and wants to:
    https://www.amazon.com/The-Singular-Universe-Reality-Time/dp/1107074061

    I mentioned earlier:
    I looked up "cosmological natural selection" in the book's index and it says that is discussed on pages
    454-460, 464, 499, 525, and 527-528.

    About "disparagement" I suspect (not having read the book) that the key idea is that "good" science should be about nature as a causal whole---the universe that we live in, and experience, and are a part of.
    Any multiplicity should be part of understanding, explaining, predicting OUR universe.

    what is disparaged I would guess is where "multiverse" or "megaverse" is a vague verbal excuse for "bad" science, and excuse for giving up on the empirical tradition and the quest for adequate reasons for what we experience of this nature, this interconnected causal unity, this universe.

    And so the Singular Universe book would happily include the CNS many-budded, many branching, picture because it EXPLAINS why the constants like alpha = 1/137 are what they are. The fine structure constant 1/137 is something we experience because it determines what chemical elements and what chemical reactions and compounds comprise our world. It is good science to ask why alpha is 1/137 rather than 1/100 or 1/150, and good to propose explanations for how that happened. CNS natural selection may be wrong, but it is a brilliantly simple attempt to explain that.
    So it is "good" science (I would guess in the value perspectives of this book) EVEN THOUGH superficially the singular many-budded evolutionary universe of CNS visually RESEMBLES the causally disconnected multiplicity of natures with unexplained random laws to which defenders of a failed theory cling as consolation and excuse for their inability to explain the world we live in.
    CNS may eventually be proven wrong, but its resemblance to what is usually meant by "multiverse" is only at a superficial level.
     
    Last edited by a moderator: May 7, 2017
  21. Dec 2, 2014 #20

    Doug Huffman

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    I pre-ordered the p-book in August when it was promised on 30 Nov by AmaXon. Yesterday I got irritated and got the KINDLE e-book and canceled the p-book order. If it is a significant book than I can get the p-book to scribble in. Already I am irritated at the clumsy access to the footnotes.
     
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