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On A Universe From Nothing

  1. Apr 28, 2012 #1

    Chalnoth

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    Sean Carroll chimes in on the idea of a Universe from Nothing, and I get a feeling that many people who browse this forum would enjoy a read through it:

    http://blogs.discovermagazine.com/cosmicvariance/2012/04/28/a-universe-from-nothing/

    Here's a quote:
    As a rule, I tend to agree rather forcefully with most things that Sean Carroll has to say, so I highly recommend a read of the whole post if this kind of topic interests you.
     
  2. jcsd
  3. Apr 29, 2012 #2
    Chalnoth, thanks for posting, great article. I really should put more effort into keeping up with Cosmic Variance.
     
  4. Apr 29, 2012 #3
    Thanks Chalnoth. I really enjoyed reading that as well. Just read the Atlantic and Scientific American pieces on Friday. Carroll provides a nice summary and, of course, I very much appreciate his handling of the goals of the philosophy of science at the end.
     
  5. Apr 30, 2012 #4
    Another great post. Is there a better blog than Cosmic Variance on cosmology? If so I havent found it .
     
  6. Apr 30, 2012 #5

    RUTA

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    A colleague and co-author on several of my papers is a philosopher of physics. As a physicist, it sometimes requires extensive discussion with him for me to understand a point he is trying to make -- philosophers are not constrained by the tacit assumptions I have adopted unwittingly over years of studying physics. Recently, we have been engaged in a protracted discussion on precisely the topic of this link. I suspect this will clear up the confusion between us and vindicate my view for once! Thanks very much for posting it, Chalnoth :smile:
     
  7. Apr 30, 2012 #6

    marcus

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    Last edited: Apr 30, 2012
  8. May 1, 2012 #7

    Chronos

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    I still have a disconnect with the 'universe from nothing' via quantum fluctuation hypothesis - what 'fluctuated'?
     
  9. May 1, 2012 #8

    Chalnoth

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    Well, I think, as Sean points out, it isn't that there was literally nothing, but rather that there was a quantum mechanical state which we might be considered to be effectively nothing (e.g. no matter fields with non-zero values).
     
  10. May 1, 2012 #9
  11. May 1, 2012 #10
    Again, thanks for an interesting link.

    I don't have time now to read all the comments, but Bravo Lee Smolin!
     
  12. May 1, 2012 #11
    symmetry=nothing?
     
  13. May 1, 2012 #12

    Chalnoth

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    What are you talking about?
     
  14. May 1, 2012 #13

    marcus

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    I'm glad you found some of the comments interesting! Here is the direct link to the first comment by Lee Smolin:
    http://www.math.columbia.edu/~woit/wordpress/?p=4623&cpage=1#comment-109957

    (Peter Woit's response: http://www.math.columbia.edu/~woit/wordpress/?p=4623&cpage=1#comment-109963 )

    And Smolin's reply:
    http://www.math.columbia.edu/~woit/wordpress/?p=4623&cpage=1#comment-109987
     
  15. May 1, 2012 #14
  16. May 1, 2012 #15
    i was reading about spontaneous symmetry breaking. i just figured that the nothing everything came from was that symmetry. a complete lack of discrimination perhaps. i have a few questions about absolute potential and nothingness, but i want to study more on the subject first.
     
  17. May 1, 2012 #16

    marcus

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    Sahmgeek, glad you found that!

    Darken-Sol, I sort of know what you mean. I wouldn't bring in the word "nothing" quite yet, I would just focus mentally on the idea of total homogeneity. It is a very speculative idea so one can't push it too far or be too precise, but it's intriguing.

    Now we have many electrons and they are all different because different things have happened to them and caused them to be here or there and do this or that.

    But suppose all the electrons were the same, with no ability to distinguish between them!
    The electron "field" would just be one bland homegeneous field. No more "many" because no more differences.

    Maybe when a prior universe collapsed and rebounded to make this one, there came a time when everything was the same.

    Suppose "here" was exactly the same as "there". Perfect and complete symmetry. Then there would not even be any proper space.

    Suppose at very high very high energy density, electrons are the same as quarks. All distinctions between particles go away. All particles are the same particle.

    So in reaching a state of maximum density the universe becomes very boring. Totally symmetric and homogeneous. Reality has been put thru the blender. then the rebound starts.

    The energy density begins to ease off and symmetries start breaking spontaneously all over the place, in every facet of reality. "This" becomes distinguishable from "that" in a vast catastrophic cracking apart....
    =========================

    It is not take seriously, just an innocent exercise of imagination. Real theory must keep in step with observation and experimental tests. But I think I can get some idea of what you were talking about.
    I just will not equate that idea of total symmetry with "nothing" because that tempts people to get into a futile discussion about words. There might be some subterranean connection, but it is not worth the risk of getting trapped in discussion on a merely verbal level.
     
  18. May 2, 2012 #17
    I just wanted to let you know that, in my opinion, you are the best poster here. You always succinctly point out the problems and inconsistencies in some of these (out-there) theories, hypotheses or conjectures.

    Thank you. You are the main reason that I continue to read this Forum.
     
  19. May 3, 2012 #18
    I understand why you are reticent to verbalise this further - subteleties in language differences will leave different desciptions to different readers.

    However I do find this a strong idea and it is something I have thought about before. As you know I am no great (nor even good) mathematician but I have a good mind for processing information without prejudice.

    Anyways I have littel further to add just wanted to recognise what you are saying.
     
  20. May 3, 2012 #19

    RUTA

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    Exactly Albert's point in his review at

    http://www.nytimes.com/2012/03/25/b...by-lawrence-m-krauss.html?_r=2&pagewanted=all

    when he says:

    Never mind. Forget where the laws came from. Have a look instead at what they say. It happens that ever since the scientific revolution of the 17th century, what physics has given us in the way of candidates for the fundamental laws of nature have as a general rule simply taken it for granted that there is, at the bottom of everything, some basic, elementary, eternally persisting, concrete, physical stuff. Newton, for example, took that elementary stuff to consist of material particles. And physicists at the end of the 19th century took that elementary stuff to consist of both material particles and electro*magnetic fields. And so on. And what the fundamental laws of nature are about, and all the fundamental laws of nature are about, and all there is for the fundamental laws of nature to be about, insofar as physics has ever been able to imagine, is how that elementary stuff is arranged. The fundamental laws of nature generally take the form of rules concerning which arrangements of that stuff are physically possible and which aren’t, or rules connecting the arrangements of that elementary stuff at later times to its arrangement at earlier times, or something like that. But the laws have no bearing whatsoever on questions of where the elementary stuff came from, or of why the world should have consisted of the particular elementary stuff it does, as opposed to something else, or to nothing at all.

    The fundamental physical laws that Krauss is talking about in “A Universe From Nothing” — the laws of relativistic quantum field theories — are no exception to this. The particular, eternally persisting, elementary physical stuff of the world, according to the standard presentations of relativistic quantum field theories, consists (unsurprisingly) of relativistic quantum fields. And the fundamental laws of this theory take the form of rules concerning which arrangements of those fields are physically possible and which aren’t, and rules connecting the arrangements of those fields at later times to their arrangements at earlier times, and so on — and they have nothing whatsoever to say on the subject of where those fields came from, or of why the world should have consisted of the particular kinds of fields it does, or of why it should have consisted of fields at all, or of why there should have been a world in the first place. Period. Case closed. End of story.
     
  21. May 3, 2012 #20
    Although I enjoy this back and forth debate, it's a bit like arguing how many angels can fit on the head of a pin. Any idea that is not falsifiable through tests or observations is just speculation. And when it comes to speculation, "the unicorns did it" is just as meaningful as anything else. It's end up my pet theory versus your pet theory, which is not very enlightening. Is the moment before the Big Bang (or its effects) observable? If so, then we will have to wait till that observation is made to construct a theory around it. If not, then theorizing about it is eternally pointless. Every pet theory about before the big bang requires some assumption. For instance, Krauss assumes the laws of physics were the same before the big bang as they are now. I could just as well assume they were not.
     
  22. May 3, 2012 #21

    RUTA

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    That's similiar to the point Carroll makes at

    http://blogs.discovermagazine.com/c...0/why-is-there-something-rather-than-nothing/

    when he writes:

    Ultimately, the problem is that the question — “Why is there something rather than nothing?” — doesn’t make any sense. What kind of answer could possibly count as satisfying? What could a claim like “The most natural universe is one that doesn’t exist” possibly mean? As often happens, we are led astray by imagining that we can apply the kinds of language we use in talking about contingent pieces of the world around us to the universe as a whole. It makes sense to ask why this blog exists, rather than some other blog; but there is no external vantage point from which we can compare the relatively likelihood of different modes of existence for the universe.
     
  23. May 4, 2012 #22

    Chronos

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    The first principle of all science is an axiom - the universe exists. We need not agree it is logical, only that it is true. First principles are unprovable according to Godel. The role of science is to push the question to the next level, not solve it.
     
    Last edited: May 4, 2012
  24. May 4, 2012 #23
    What's the opinion on the "The Grand Design" by Stephen Hawking ?

    Is it a good reference for one who is interested in these sorts of questions?
     
  25. May 4, 2012 #24
    from what i have read, our universe is heading toward this state. in my understanding isnt heat death where all the energy is so spread out that it fails to hold any thing together. everything will just end up being the same thing. "quark soup" some one said. that is unless our universe is being infused with energy from an external source.
     
  26. May 4, 2012 #25

    marcus

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    Actually "heat death" is not what I had in mind when I posted the above, D-S, but it's of no great importance. There are limits to how speculative I'd like to get and I said about all I can there already.

    One reason that it is interesting to think about conditions at the start of expansion is that we can see possible evidence---traces in the sky of what it may have been like. It's very difficult to infer anything, but at least there is something to look at and analyze.

    Compared with that, the future (say 50 or 100 billion years from now) is a closed book.

    So well, first of all we don't HAVE to speculate at all, there's plenty of stuff in cosmology that can be learned based on concrete evidence and people are learning more and more all the time. But if one DOES venture into speculation then I'd say early universe conditions are a lot more interesting---and that means asking what matter and geometry could be like at very HIGH energy density.

    So one is not asking about very cold empty conditions, one is asking what nature is like at very very hot dense conditions. And one idea floating around is that nature might get more symmetric in various fundamental ways---eg forces which look different to us might turn out to be the same, particles that look different might turn out to be the same, or there might not be anything you'd call a particle----if things are somehow too densely packed for there to be separate entities. Geometry might act different---what we call gravity is an effect of dynamical geometry and at extreme density geometry might, for example, repel rather than attract. (According to the Loop school of thought this effect is responsible for the beginning of expansion--a rebound from a collapse which achieved the maximum possible density). There's a lot to wonder about concerning early conditions---the extreme hot dense state at the start of expansion.

    I wouldn't call that the beginning of the universe or of time or anything grandiose like that. As far as we know it's just the start of the expansion which we observe and measure. It may be possible to infer and model back further in time than that, if we study the available evidence closely enough.
     
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