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Pre big bang cosmology

  1. Aug 23, 2010 #1
    Is there a consesnsus as to whether the big bang represent an ultimate begining ?

    it seems to me that the answer to that question is no.

    The reason for this is that we need a quantum theoy of gravity to describe the moment of the big bang and all current attempts at this eg LQG, Hoyava gravity etc all imply that there was a pre big bangs scenario. Evven if these aproaches are wrong it doesnt change the fact that we cant be sure of what happened until we do have a cosnsitent theory of Qauntum gravity

    Furthermore inflation can be formulated to imply many big bangs eg eternal inflation.
    Whilst Guth, Vilenkin and Borde have proposed inflation cannot be eternal in the past. This has beeen disputed by Aguire and Graton so there seems to be no consesnus on this issue either.

    In short we cannot say the big bang represents an ultimate begining. We cant even be sure that there was an ultimte begning.

    The situation is still unresolved in cosmology.

    Anyone disagree?
     
  2. jcsd
  3. Aug 23, 2010 #2

    marcus

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    If you google "springer vaas beyond" you get
    http://www.springer.com/astronomy/cosmology/book/978-3-540-71422-4 [Broken]
    the Springer.com webpage for a book being assembled by science editor Rudy Vaas.
    Chapters by 10-20 experts--main proponents of various pre-BB concepts. 680 pages, 40 illustrations.

    Here are excerpts from the publisher's page:
    The book has been very slow to appear. Reviewer's (draft) copies have been circulated but the production schedule keeps slipping. I think this is because each chapter is supposed to be written by an expert on that particular concept. It is hard to get experts, maybe, to all write at the same style-level (for wide audience)--especially when they are all rivals of each other.

    Plus in some cases the models are evolving so that in 2 or 3 years they can get out-of-date already. This I know to be true in Loop Quantum Cosmology which has developed radically since 2006 (when Vaas began to assemble chapters for the book).

    It seems almost like an impossible book to compile and publish. But anyway the current estimate of when it will be out is December 2010.
     
    Last edited by a moderator: May 4, 2017
  4. Aug 24, 2010 #3
    Wow cant wait to get that book.

    So i guess the answer to my question is that you agree with my summary?
     
  5. Aug 24, 2010 #4

    marcus

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    I agree with your summary.

    However I probably will not buy Vaas' book because
    1) it will be expensive
    2) the 600 pages include many chapters about pre-bang ideas that don't interest me (this could be an indication of limitations on my part)
    3) I will probably be able to borrow the book at the local UC library and look at it
    4) Vaas began collecting articles around 2006 and didn't move fast enough, some of the material is probably out-dated

    I think Vaas' book will send a valuable message by its simple existence---without our having to buy and read it. It will demonstrate to a wide audience that a wide range of professionals study pre-bang cosmology and have a wide range of ideas about how to model it. It will help to "put the subject on the map".

    If you want to glance at the titles of current research in this general area (quantum cosmology) here is a search in the Spires data base.
    date > 2006
    keyword "quantum cosmology"
    http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+dk++quantum+cosmology+and+date+%3E+2006&FORMAT=www&SEQUENCE=citecount%28d%29 [Broken]
    In this listing the articles are ranked by how often they have been cited--a rough indicator of importance. These are professional research articles and often not very readable, but if you click where it says "abstract" you get a brief summary, which though incomprehensible is at least short.

    You can change a setting to get the articles to be listed newest-first---in descending date order
    http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+DK+QUANTUM+COSMOLOGY+AND+DATE+%3E+2006&FORMAT=www&SEQUENCE=ds%28d%29 [Broken]
     
    Last edited by a moderator: May 4, 2017
  6. Aug 24, 2010 #5
    Sounds like fun philosophy and metaphysics, not physics.
     
  7. Aug 24, 2010 #6

    marcus

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    I follow LQC (loop quantum cosmology) which is definitely physics, not metaphysics. One trouble with that book is that the editor Vaas has mixed LQC in with some "multiverse", string theory, and "eternal inflation" stuff----speculative at best and entirely non-empirical at worst.

    LQC is starting to be accepted as a part of observational cosmology. Check out the papers of Aurelien Barrau. He believes he can identify effects of the LQC bounce to look for in the CMB.
    Gave a paper on this in Paris this summer at the 35th ICHEP (international conference on high energy physics).

    Skepticism is always welcome, if you would like to take that stand. But I would not advise it. I think the current LQC models could easily prove wrong (when compared with data) but I do not think they will turn out to be mere metaphysics :biggrin:

    Here is a sampling of Barrau's recent papers (he used to be more interested in string than he is today, his interest has shifted somehat in the past 2 years)

    ==quote search: http://arxiv.org/find/grp_physics/1/au:+Barrau_A/0/1/0/all/0/1 ==

    1. arXiv:1003.4660 [pdf, ps, other]
    Inflation in loop quantum cosmology: Dynamics and spectrum of gravitational waves
    Jakub Mielczarek, Thomas Cailleteau, Julien Grain, Aurelien Barrau
    Comments: 11 pages, 14 figures. Matches version published in Phys. Rev. D
    Journal-ref: Phys.Rev.D81:104049,2010
    Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)

    2. arXiv:1001.2973 [pdf, ps, other]
    Very high energy gamma-rays and the Hubble parameter
    A. Gorecki, A. Barrau, J. Grain, E. Memola
    Comments: Proc. of the 12th Marcel Grossmann meeting on general relativity. 3 pages, 1 figure
    Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)

    3. arXiv:0911.3745 [pdf, ps, other]
    Loop quantum gravity and the CMB: toward pre-Big Bounce cosmology
    Aurelien Barrau
    Comments: Proceedings of the 12th Marcel Grossman Meeting on General Relativity. 3 pages, no figure
    Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)

    4. arXiv:0910.2892 [pdf, ps, other]
    Fully Loop-Quantum-Cosmology-corrected propagation of gravitational waves during slow-roll inflation
    J. Grain, T. Cailleteau, A. Barrau, A. Gorecki
    Comments: 9 pages, no figure, minor corrections
    Journal-ref: Phys.Rev.D81:024040,2010
    Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)

    5. arXiv:0902.4810 [pdf, ps, other]
    Internal structure of a Maxwell-Gauss-Bonnet black hole
    S. Alexeyev, A. Barrau, K.A. Rannu
    Comments: 5 pages, 5 figures, published version with minor changes
    Journal-ref: Phys.Rev.D79:067503,2009
    Subjects: General Relativity and Quantum Cosmology (gr-qc)

    6. arXiv:0902.3605 [pdf, ps, other]
    Inverse volume corrections from loop quantum gravity and the primordial tensor power spectrum in slow-roll inflation
    J. Grain, A. Barrau, A. Gorecki
    Comments: 15 pages, 5 figures, published version with minor modifications, results unchanged
    Journal-ref: Phys.Rev.D79:084015,2009
    Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)

    7. arXiv:0902.0145 [pdf, ps, other]
    Cosmological footprints of loop quantum gravity
    J. Grain, A. Barrau
    Comments: Accepted by Phys. Rev. Lett., 7 pages, 2 figures
    Journal-ref: Phys.Rev.Lett.102:081301,2009
    Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th); Quantum Physics (quant-ph)
    ==endquote==
     
    Last edited: Aug 24, 2010
  8. Aug 24, 2010 #7
    I should have been clear, I don't believe that the theory is metaphysics, just what is presented in the book, for the reasons you've described. It's unfortunate when authors feel the need to conflate notions to promote their personal "flavor" of a theory. I apologize for the misunderstanding.
     
  9. Aug 24, 2010 #8

    marcus

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    I'm happy with your reaction which was in effect constructive. You put the spotlight on a helpful distinction and it spurred me to gather links bearing on the observational cosmology side.

    In Vaas defense, he chose a hard row to hoe. A difficult book project. Because a lot of the public has multidimensional fantasy expectations and Vaas wanted to write a midlevel book delving past the big bang, that would SELL. That meant meeting mass audience expectations at least half way. He also wanted the book to be by experts, each chapter by a different proponent. He is a philosopher of science by training and also a science writer/editor of the 'Scientific American' sort. So for maximum credibility he got them to write the chapters, rather than doing it himself based on interviews.
    The self-regard of the experts may have occasionally impeded progress, or it may at times have been like herding cats. In any event the book got to be very fat (around 650 pages) and expensive. Over $80.

    I guess I'm waiting for the NEXT book on pre-bang cosmology. :biggrin:
     
    Last edited: Aug 24, 2010
  10. Aug 24, 2010 #9
    Are you familiar with the development (or not) of the video game Duke Nukem Forever? It makes me think of this book...

    I see your point about the nature of the writing, and the intended audience, but I still think that kind of book does LQC no favors. As you say, it's gaining mainstream and observational acceptance, so the need for a book where the science is mingled with the arcane seems counterproductive. Anyway, I enjoyed the links you provided, which are remarkably thorough.
     
  11. Aug 25, 2010 #10
    I think theres nothing wrong with speculative physics as long as one makes it clear which part is speculative and which is not. Many ideas in physics that have been tested were not testable when they were first proposed. My point would be that to say there was a time before the big bang as many quantum gravity theories do is no more specualtive than to say there was nothing before the big bang. Not that one statement is wrong and the other correct.
     
  12. Aug 25, 2010 #11
  13. Aug 25, 2010 #12

    marcus

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    I happened to attend a lecture by him at UC-LBL (i think in 2006 or 2007) where he made a case for the idea.
    A similar talk is available online video at the Perimeter Institute archive PIRSA, and at other sites. You might like to watch it.
    If you google "pirsa penrose" you get these 4 online video lectures:
    http://pirsa.org/index.php?p=speaker&name=Roger_Penrose
    and the one with the word "outrageous" in the title would be one where he presents this idea.
    But I just looked at the PDF slides that go with the most recent one (2008) and he seems to be giving the same lecture!

    He also gave the same talk at Cambridge in Fall 2005 and it is online as slides and audio. The hand-drawn slides look the same or nearly. He's given the talk a lot of times.

    I don't know anything more about the book. Here is the amazon.co.uk page:
    http://www.amazon.co.uk/Cycles-Time-Extraordinary-View-Universe/dp/0224080369/

    It is due out around 20 September and is selling well, pre-order, already. Salesrank #1 in science books at amazon.co.uk.

    His idea is bold, mathematically logical, and eccentric---brilliantly presented (in the lecture format) with charm and colorful illustration. I'm not a fan of the idea, though I respect Penrose and wish the book all possible success. He seems to me to have honesty and frankness. At least in this book he doesn't pander to wide-audience religious susceptibilities---some authors flirt: "it looks so neat and benign it almost could have been designed, could it not? *coy smile* but Science says it wasn't." In the talk I saw, there was none of that, not even the faintest suggestion of peek-a-boo divinity.

    His conjectured cycle takes an almost inconceivably long time. All the stars have to burn out and gradually collect to form black holes and the black holes have to evaporate so that finally there is nothing left in the universe but uniform radiation.
    Nothing remotely resembling a clock or a meter-stick remains. And then, Penrose argues, who could tell the difference between this conformal cosmic boredom and a big bang? So, even though you did not hear the bang, it has all started again!

    I'd heaps rather focus on something more practical to test, even if it eventually turned out wrong---then one gets to say "OK that was wrong because of so-and-so, now let's see how we can get around that and make something better..."---that approach seems to have more traction.
    (Just a subjective personal inclination.)
     
    Last edited: Aug 25, 2010
  14. Aug 25, 2010 #13
    I agree about your point to pandering to the religious audience. I was wondering if you had anyone in mind? I think Hawking uses the word god to help sell more books, despite the fact that its claimed hid wife said his lack of religion helped end their marriage. His new book "The Grand Desgin" seems also to use the buzz words popular in religious circles although I doubt hell be pushing their agenda, we'll see .
    I hope it has some interesitng physics and not just his own ideas. I like the way Vilenkin for example explained the Hawking Hartle model and contrasted it with his own quantum tunneling proposal. Although I would have liked it if he had discussed Aguirre and Graton's past eternal inflation proposal. Thats why I guess im looking forward to reading the Vaaas book to take a survey of the different possibilities being presented.
     
    Last edited: Aug 26, 2010
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