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Something and Nothing of Universe

  1. Feb 5, 2009 #1
    Many people say that the Universe essentially arose from nothing. Does anyone know if it is possible for "nothing" to be created?
     
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  3. Feb 5, 2009 #2

    marcus

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    Do any professional cosmologists say this? I wouldn't go by what "many people" say, or by what was written 5 or 10 years ago.
    Above all don't go by what you read in popularization books, mass media magazines etc.
    What do cosmologists actually say in their technical journal articles (not for pop media consumption.)

    I don't know any who say the universe arose from nothing.
    If you do, could you find us an article where there is some quote to that effect?

    It would surprise me and would be quite interesting, if you could find some reputable person really saying that :biggrin:
    because the standard cosmo model that they pretty much all use does NOT say that about "arose from nothing."
    My impression is that "arose from nothing" is popular BS or some kind of infectious misconception. But I'd be glad to
    see some recent professional article that confirms what you say.

    In case you would like some non-technical reading to bring you up to date, try the Einstein Online cosmology pages.
    http://www.einstein-online.info/en/spotlights/cosmology/index.html
    I've got the link in my signature as well.
    One of their webpages is about confusions people have about what is meant by the Big Bang, astronomers mean two different things by it
    and they clear up some of the misunderstanding that this causes.
    http://www.einstein-online.info/en/spotlights/big_bangs/index.html
    This is popularization writing, part of the Einstein Institute's outreach program. I suggest it for what it's worth in case it could be helpful.
     
    Last edited: Feb 5, 2009
  4. Feb 5, 2009 #3

    xantox

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    A famous one is:
    A. Vilenkin, "Creation of universe from nothing", Phys. Lett. B, 117B, 25-28 (1982).

    But see also, using other words but with similar meaning:
    S. W. Hawking, N. Turok, "Open inflation without false vacua", Phys. Lett. B, 425, 25 (1998).

    The meaning of "nothing" is here extremely characterised, eg it means that the classical 3-geometry and matter vanishes entirely. This should be taken not as a way open towards cheap philosophy, but quite to the opposite, as an opportunity to doubt that the very concept of "nothing" may have an absolute physical scope.
     
    Last edited: Feb 5, 2009
  5. Feb 5, 2009 #4

    marcus

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    I know about the way people speculated back in 1980s and 1990s.
    What I'd like is something more recent than that, preferably > 2004 or 2005.

    My impression is all that "universe from nothing" stuff went out the window by 2005.
    (It's a date Roger Penrose gave in a lecture at Cambridge where he was talking about ideas of before the big bang.)

    Anything professional from > 2004?
    I'd be interested!
     
    Last edited: Feb 5, 2009
  6. Feb 5, 2009 #5

    xantox

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    A very interesting one is R. Bousso, "Holographic Probabilities in Eternal Inflation", Physical Rev. Lett., 97-19, (2006).
     
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  7. Feb 5, 2009 #6

    marcus

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    And that is an example of where our expansion episode arises from something, an occurrence in some other part of of the universe.

    I checked the paper and Raphael Bousso never says that our big bang expansion arose from nothing. That would be misleading language. It would not convey what he is trying to say, and he doesn't use the word. Bousso is proposing a definite condition leading up to BB. In fact Bousso is one of the authors to be included in a new book about conditions prior to the big bang which is supposed to come out in August of this year. You may know the book, it is edited by Ruediger Vaas and is called Beyond the Big Bang.

    I repeat my request. Please anyone come up with a recent professional cosmo article where the author says our bigbang expansion arose from nothing.
     
    Last edited: Feb 5, 2009
  8. Feb 6, 2009 #7

    xantox

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    Actually, not. It really describes several disconnected regions nucleating "from nothing". If you really need the quoted term here, it appears briefly in a related paper by R. Bousso, B. Freivogel, I-S. Yang, "Eternal Inflation: The Inside Story", Phys. Rev. D74-10 (2006), but even if it is not spelled out as such in that and in several other papers, that is what the equations mean essentially. Note that Bousso has worked closely with Hawking and then Linde who both strongly supported such ideas. This is just one example, variants of this beautiful approach have in fact become rather common.

    Again, "nothing" is there perfectly soundly defined as meaning "vanishing classical spacetime and matter".
     
    Last edited: Feb 6, 2009
  9. Feb 6, 2009 #8
    Physics is living by theory, observations and experiments.
    I can't see how or where "nothing" fits in. No experiments or observations of "vanishing" ever noticed.! Or who did?
     
  10. Feb 6, 2009 #9

    marcus

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    Where? I looked thru the whole article and could not find anywhere they say the universe arose from nothing.

    The whole article is about a very definite idea of the something from which they think the universe could have arisen!

    Hi Hurk,
    here is the link to the article that Xantox thinks we should look at:
    http://arxiv.org/pdf/hep-th/0606114v2
    I find it is typical of a lot of current research that delves into what conditions might have been like before the big bang episode.
    Many of the different approaches will be collected in a forthcoming book called "Beyond the Big Bang: Prospects for an Eternal Universe"
    scheduled to come out this year. Loop cosmology bounce will feature in several of the chapters, and (Bousso and others') eternal inflation ideas will also be included. Before the big bang topics are becoming a lively research area!
     
    Last edited: Feb 6, 2009
  11. Feb 6, 2009 #10

    xantox

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    Here some quotes at random, it is a frequently used term in the literature.
    • Bousso and Freivogel, Yang: "If one imagines that the universe was created, perhaps by 'tunneling from nothing' [..]"
    • Bousso and Linde: "Alternatively, one may consider the quantum creation from nothing of a closed inflationary universe [..]"
    • Bousso and Chamblin: "It may be interpreted to describe the semiclassical creation from nothing of two open universes [..]"
    • Vilenkin: "A cosmological model is proposed in which the universe is created by quantum tunneling from literally nothing into a de Sitter space."
    • Hawking and Hartle: "In other words, the ground state is the amplitude for the universe to appear from nothing".
    • Zel'dovich: "Spontaneous creation from nothing does not contradict the laws of conservation".
    • Linde: "The most natural way to realize inflationary scenario in this theory is to assume that the universe was created 'from nothing'".
    • Carroll: "This might be the case, for example, if the universe were created 'from nothing' [..]"
    • Polchinski: "The states of positive ρV would also be populated by any sort of tunneling from nothing [..]"
    • Garriga: "An inflating brane-world can be created from 'nothing'".

    I must insist on the physical definition of the word "nothing" in all the above quotes as meaning the vanishing of classical spacetime and matter.
     
    Last edited: Feb 6, 2009
  12. Feb 6, 2009 #11

    marcus

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    The point I made earlier was that people used to talk this way particularly in the 1980s and 1990s, but it seems to have gone out of fashion. And I think for good reason! In order to use your quotes to check my impression, I need dates.

    Links to the papers would be helpful. I need to see things in context to know what they are actually saying.

    I'm not interested in stuff before 2005. The Bousso Chamblin paper and the Bousso Linde paper are from 1998. No need to bother with those.
    Hawking and Hartle would be their 1983 paper I expect. If so we can ignore that one.
    Zel'dovich died in 1987.
    Your Vilenkin quote is from 1982.

    Turning to more recent stuff, notice that Carroll (presumably a more recent example) uses inverted comma scare quotes and considers a hypothetical case--"if the universe were created 'from nothing.'"
    Bousso Freivogel and Yang also use scare quotes in an iffy imaginative statement "if one imagines that.....perhaps by 'tunneling from nothing.' "
    Inverted commas used like that means not really but in a manner of speaking.

    I'm afraid I can't accept these quotes, out of context, without links and page references so I can see what they are talking about, as evidence that the professionals are claiming that the universe arose from nothing.

    When one looks at what they actually say one sees that there is a lot of structure postulated in the pre-bigbang state. Very much something.
    I think what you present as THE definition of nothing is your own private definition :biggrin:. Simply the absence of ordinary matter and the failure of spacetime to be classical is not what many experts would call nothing.
     
    Last edited: Feb 6, 2009
  13. Feb 6, 2009 #12
    This is also the way I've learned to think about "the universe came from nothing" or "spontaneous particle generation" statements. There's always some sort of 'nonclassical' mathematical model that "nothing" or "spontaneous" refers to -- and those models are, as you point out, "very much something".

    Regarding redhedkangaro's question -- "Does anyone know if it is possible for 'nothing' to be created? -- would it be acceptable to entertain the idea that, at least wrt some universal evolutionary scenarios, our universe is in the process of becoming nonexistent (ie., literally nothing)?

    Edit: On second thought, maybe it's just a nonsensical question.
     
    Last edited: Feb 6, 2009
  14. Feb 7, 2009 #13

    xantox

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    There are two aspects that you're addressing here, 1) terminology, 2) theory. Let's see each separately.

    1) Terminology. About the use of the word "nothing" in theoretical cosmology. You said that "When one looks at what they actually say one sees that there is a lot of structure postulated in the pre-bigbang state. Very much something."

    Your argument seems to be that since there are some equations describing some kind of state, we can call that "something" and so it is fundamentally wrong to use the term "nothing". But here you clearly use the words "something" and "nothing" in the inappropriate definitions of a dictionary or traditional philosophy. These definitions are of course forbidden in the context of physical theories. It would be like for cosmological "quintessence" starting to debate that the term is incorrect since it is not really a fifth essence, or like for a "black hole" starting to debate that the term is incorrect since quantumly it is not totally black, or like for quantum field theoretical "vacuum" starting to debate that the term is incorrect since that vacuum is very much non-empty.

    This is exactly what I warned against in my first comment above, that we should avoid entering speculations based on philosophical definitions. When "vacuum" is a term clearly defined in a physical theory, that is all we need, and even if some authors would start calling it differently tomorrow but with the same underlining definitions we would know we're talking about the same and so the specific choice of term used remains purely anecdotical and irrelevant. Thus, the same applies to "nothing", once it is a term clearly defined in the literature, and since it is, we can agree on the definition and that can be more than enough. As per where is defined, the following is a primary and sufficient source (other scholars use the exact same definition): "In this paper, I shall discuss a model in which the universe is created by quantum tunneling from 'nothing', where by 'nothing' I mean a state with no classical space time" [1].

    You could still object that it is better when the terms used in a physical theory are chosen so as not to be confusing or contradicting with everyday meanings. Such as, why call "vacuum" a state which is not really empty and "nothing" a state which is not really nothing so that we have just "a manner of speaking" with "scare quotes". This objection is thus purely philosophical, but I shall reject it on the following basis. For classical observers, vanishing of classical fields is the best possible definition of classical nothingness. Trying to consider that the word "nothing" must refer to some kind of "absolute physical nothingess" (which you do by considering that those models are "very much something") is however meaningless: the philosophical idea of "absolute nothing" is pure nonsense, it is a classical concept which cannot have an absolute physical meaning.

    The above definition from Vilenkin (who also use the expression "literally nothing" without quotes) is thus also appropriate on this aspect. "Nothing" is here classical nothingness, and any theory of quantum gravity which can describe spacetime as an emerging entity -can- describe such "nothing" in terms of a quantum wavefunction, and there is no contradiction.

    2) Theory. Let's now turn very briefly on the underlining theoretical frameworks of the "universe from nothing" approaches instead than on the word "nothing". The idea that the universe can be originated with a quantum fluctuation from a state devoid of classical spacetime is of course one amongst many others but it is perhaps the most well-known one. The line of research was originated by Tryon [2] and then culminated with Vilenkin [3], Hawking and Hartle [4], Moss and Wright [5] and Linde [6]. It is based on the euclideanized path integral to define the tunnelling amplitude of the universal quantum wavefunction into classical spacetime. The transition can be described with a specific kind of instanton for different initial conditions, such as the de Sitter instanton, the Hawking-Moss instanton for closed FRW universes, or the Hawking-Turok instanton for open FRW universes.

    Further developments have been made in string cosmology, where the "nothing" can be identified with the string perturbative vacuum itself (so that the approach is particularly significant to find a selection mechanism out of the exceedingly big landscape of vacua). In particular there is the generalization to the brane world scenario by Hawking, Hertog and Reall [7] and Garriga and Sasaki [8].

    But there are other completely different lines of research which are generally similar on this aspect of picturing a transition from a classically forbidden region. You said "you're not interested in stuff before 2005". But on one hand, we should not be quite interested in dates at all, as it is not the freshness of research that determines its interest and the newest ideas are not always a progress. The scientific method works well enough to exclude by itself the dead paths and to identify the weaker paths, that we do not need to focus only on the newest ideas. But on the other hand, even those latest approaches such as Loll's CDT, which you may consider more fashionable, can be considered a kind of "universe from nothing" theories as well, since spacetime is emerging from a non-classical region of the wavefunction (in that specific case there is also a difference that only the scale factor is vanishing).

    ______
    [1] A. Vilenkin, "Quantum origin of the universe", Nuclear Physics B 252, 141-152 (1985).
    [2] E. P. Tryon, "Is the Universe a quantum fluctuation?", Nature 246, 396-397 (1973).
    [3] A. Vilenkin "Creation of universes from nothing", Phys. Lett. B, 117 B, 25-28 (1982).
    [4] J. B. Hartle and S. W. Hawking, "Wave Function Of The Universe", Phys. Rev. D 28, 2960-2975 (1983).
    [5] I. G. Moss and W. A. Wright, "Wave function of the inflationary universe", Phys. Rev. D 29, 1067-1075 (1984).
    [6] A. D. Linde, "Quantum creation of an inflationary universe", Sov. Phys.-JETP 60:2401-405 (1984).
    [7] S. W. Hawking, T. Hertog, and H. S. Reall, "Brane new world", Phys. Rev. D 62:4, (2000).
    [8] J. Garriga, M. Sasaki, "Brane-world creation and black holes", Phys. Rev. D 62:4 (2000).
     
    Last edited: Feb 7, 2009
  15. Feb 9, 2009 #14
    xantox, I think your points are well taken. However, I also think that it's a good thing (ie., confusion and obfuscation is minimized) when physicists, cosmologists, etc. avoid appropriating (or misappropriating) ordinary language terms to refer to theoretical inventions (even though the practice usually serves some mnemonic purpose).
     
  16. Feb 9, 2009 #15
    Yes Thomas,
    I agree, it would be better if ordinary people were not annoyed by inventions by scientists, inventions they define or mention “nothing”. In fact the discussion here is about reality whatever that means. Personally I find myself confronted with an autonomous reality which can never fully understood by whatever theory and its underlying models. By the way what did redhedkangaro mean with his understanding of his "nothing"?
    Kind regards
    Hurk4
     
  17. Feb 9, 2009 #16
    I enjoyed reading posts -- thanks. One of my christian friend said, the initial state of big bang is the soul of God. And I think there can be many even infinite number of universes, but simple they do not interfere. However I like to think of the origin of my universe.
     
  18. Feb 9, 2009 #17

    marcus

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    Hi Thomas,
    thanks for the reply. I think we all realize that the prebigbang conditions people postulate are indeed "very much something!"

    The main point I've been making is that since 2000 (and especially since 2005) there has been a change in how scientists talk about it. In the 1980s and 1990s it was fashionable to call these nonclassical conditions "nothing".

    But since 2000 they do that less and less. Since 2005, as far as I know, not at all. And I think with good reason. Calling such conditions "nothing" is a misnomer and misleads people.

    If we were to take the definition seriously that was proposed earlier, that 'nothing' (by which I mean xantoxian 'nothing') is merely a period when vintage-1915 classical spacetime doesn't apply and there's no ordinary matter, then the answer is YES!!!

    In Loop cosmology there is a collapsing prior universe (conventional classical spacetime and ordinary matter) which then undergoes a big crunch, which causes a high density state in which there is momentarily no ordinary matter and no classical geometry. This then begins to expand and becomes what we see.

    The Loop people call this a quantum regime---a brief period when geometry is not governed by classical GR but functions according to a quantum version of GR. They don't call it 'nothing' even tho it satisfies xantox' definition! This is only one example, and is well known.

    My point is that the Loop researchers do not call this brief bounce episode 'nothing'!
    If they would use the xantoxian definition (which apparently very few people do nowadays) they would say there was a classical universe collapse, which caused a 'nothing', which then in turn caused the expansion that we see. They don't talk this way, and neither do other researchers studying other pre-big bang models. As a somewhat misleading figure of speech it is going out of style.

    One reason people don't call these conditions 'nothing' any more (except for a few like xantox) is precisely because they want to study these conditions.
    They want to model them, and if possible derive predictions of things to look for in the CMB--some models may have distinctive signatures which we can detect or not detect, providing a way to test.
     
    Last edited: Feb 9, 2009
  19. Feb 9, 2009 #18

    xantox

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    It is true that it is less used, I did not oppose that. But note that the originators did not apparently consider it a misnomer at all, as Vilenkin considers it literally nothing, such as in "nothing is nothing". While it is true that this choice of term was also a way to emphasize the provocative character of the new proposal, it should also be carefully considered that "vanishing of classical fields" is a rather good physical definition of "no-existing-thing", "things" being implicitly classical entities in spacetime and unless we can try to come up with an even better physical statement roughly corresponding to the everyday word "nothing" which however I don't know of. There is a respectable western philosophical tradition, which you're in fact following, believing to be able to define more absolute notions of 'nothing' on purely logical terms but which I consider profoundly misguided.

    Thank you, but it's not xantox' definition but Vilenkin'. Note that I'm not arguing to affirm my personal views or to contradict yours but to restate those historical facts which originated the expression discussed in this thread. Also, no final word has been spoken on tunnelling theories which remain extremely attractive and it would seem likely that they will also at some point get restated as approximations of newer theories.

    Anyway, concerning LQC, there is a theoretical reason preventing to say the universe "came from nothing", since in Bojowald's theory there is a deterministically evolved transitory bounce at nonzero volume from a pre-big bang classical state. This reason is however not present for example in Loll's CDT, where the scale factor vanishing dynamics behaves quite similarly to Vilenkin theory (even if it has some essential differences in respect to a tunnelling scenario). It is perhaps not entirely semantically random that Loll wrote an article in 2007 and gave a conference in 2002 on the theme "Spacetime from nothing".

    Note that there are also other more extreme possibilities, such as a completely vanishing wavefunction in the forbidden classical state.
     
    Last edited: Feb 10, 2009
  20. Feb 9, 2009 #19

    marcus

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    Pretty nearly semantically meaningless. Loll's simulations do not start from nothing. They start from a minimal set of simplices. I forget how many, a dozen maybe. This continues along for a while and then takes off. At no point in the simulation are there zero simplices.

    I think when Loll says "universe from scratch" she means that she gets something like a classical spacetime to emerge from very minimal fundamental elements. This doesnt refer to emergence in time but from a minimal ground---the simplest logical components.

    What is the 2007 article where she says 'emerged from nothing'?
     
  21. Feb 9, 2009 #20

    marcus

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    Good, that was the point I was trying to make.

    There has been a change in language among professional researchers.
    It was fashionable to say 'nothing' in the 1980s and 1990s. (When Vilenkin was doing what he's mostly known for.)

    It has gone out of fashion.

    Penrose pointed out the change in fashion in 2005 in a very pronounced way about the time he began presenting his own version of the "something" before the bang started.
    It is good for lay people, I think, to realize that the prevailing professionals no longer refer to pre-bigbang conditions as 'nothing'.
     
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