Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Universe from nothing

  1. Feb 5, 2015 #1
    Hi
    I am new on here, so please forgive me if this is in the wrong place. I am currently an Undergraduate physics major at UCLA, and want to pursue cosmology as a career eventually.

    A few of my friends are big fans of Lawrence Krauss, and recommended his book, a Universe from Nothing. I searched for it in Google, and found an arXiv article by a mathematical physicist, who has disproved many of the claims in the book. Since the article has mathematics that is way above my head, I'm wondering if other experts could analyze some of the claims? The author even acknowledges George Ellis, which may indicate that it is on firm ground. If so, why does Krauss continue to garner so much attention, if his claims are imcorrect. Here is the article: https://inspirehep.net/record/1298212?ln=en
     
  2. jcsd
  3. Feb 5, 2015 #2

    phinds

    User Avatar
    Gold Member
    2016 Award

    For one thing, Krause is very articulate, personable, and charming. I don't care for his theory of a universe from nothing (I have the book) but I find him entertaining, both in writing and on TV shows. It's possible that he's doing what he does for the money but I doubt it. I think he believes what he says he believes. Yeah, the TV shows he likely does for the ego gratification, but I think he says what he believes when he's on them.
     
  4. Feb 5, 2015 #3

    PeterDonis

    User Avatar
    2016 Award

    Staff: Mentor

    I can't fully evaluate all of what the article is saying, since in many places it refers to other literature that I'm not familiar with for important details. But it seems to me that the article isn't really "disproving" Krauss's claims, but just pointing out qualifications that Krauss doesn't give in his book.

    For example, the first claim of Krauss's that the article analyzes is his claim that GR says a closed universe with ordinary matter and energy must recollapse. The article points out that, strictly speaking, this isn't true, since there are solutions to the Einstein Field Equations that are spatially closed, with ordinary matter and energy, but which don't recollapse. But these solutions (which are given in other papers referred to in the article) are highly anisotropic (at least, that's what the article is saying), and all our observations, as far as I know, indicate that our universe was isotropic to a very high degree for as much of its history as we can observe or gain evidence of. So while it's technically true that a closed universe, in general, is not required by GR to recollapse, if our actual universe is closed, it would be described by a solution that does recollapse. Since Krauss's book is a pop science book and not a technical paper, it doesn't surprise me at all that he wouldn't go into those kinds of technical issues.
     
  5. Feb 5, 2015 #4

    Chalnoth

    User Avatar
    Science Advisor

    First, I haven't read A Universe From Nothing, but I understand that many physicists consider the book to be rather imprecise and potentially misleading. That said, my response:

    I think many of his criticisms are rather off-base.

    The problem here is that the popular language which Krauss has used in his book is necessarily imprecise: it is just not possible to accurately describe fundamental physics without resorting to jargon and mathematics. I think the author of this paper has read into Krauss's statements some things which he probably did not mean.

    To take one example, consider point two:
    Kohli responds to this by talking about how this is only true if you make certain assumptions about the early universe. But he seems to go too early: Krauss is talking about the behavior of spatial curvature in relation to matter and radiation. As long as the universe is dominated by matter or radiation, even a tiny amount of curvature will come to dominate the future expansion history. It's pretty easy to calculate, for example, that for the curvature to be small today, it had to be unbelievably tiny in the early universe. This was, originally, one of the major motivations for cosmic inflation.

    Note that as our current universe is dominated by dark energy, the impact of curvature on the expansion will decrease in the future. So if there is any spatial curvature right now, its impact on the expansion will become smaller and smaller into the future.
     
  6. Feb 5, 2015 #5

    Garth

    User Avatar
    Science Advisor
    Gold Member

    I do have (Kindle version) and I have read the book.

    I can see how the book would convince an atheist like Lawrence Krauss himself, but actually I was rather disappointed.

    In the UK we have an advert for varnish (paint) that uses a slogan that has become a common phrase, "It does what it says on the tin".

    The problem is that this book does not do "what it says on the tin", 'A Universe from Nothing'.

    Krauss has not answered the question “Why There is Something Rather than Nothing?” because he does not start with nothing, he starts with a quantum vacuum.

    This highly complicated state is determined by strict quantum laws of physics which also happens to be a component of our universe that already exists.

    But where did those laws themselves come from? Why do those laws seem to take the form of quantum mechanics with some particular wave function and Hamiltonian?

    Just a thought.

    And welcome to these Forums Thomas Moore! :)

    Garth
     
  7. Feb 5, 2015 #6

    Bandersnatch

    User Avatar
    Science Advisor

    While I can't comment on the article, here's one of talks by Krauss encapsulating the ideas from his book:


    Perhaps the most enlightening is the panel discussion/Q&A session starting at about 1:13:00. There you can hear Krauss' colleagues addressing some of the language he uses, including the 'nothing', that - as explained above by Garth - is not really nothing.
     
  8. Feb 5, 2015 #7

    Garth

    User Avatar
    Science Advisor
    Gold Member

    Thank you for that link Bandersnatch - yes, the lecture and the questions/discussion were very interesting but nothing new other than what's in his book and the discussion we have had here in various threads about the subject.

    Gates suggested that in his own research into string theory and super-symmetry he had found some "minor evidence" of 'natural selection' which might apply to the evolution of our universe in the multiverse (CNS theory). When pressed as to what he meant by "evidence", was it "testable evidence"? He had to admit no, not testable.

    Wilczek pointed out that he had said years ago that the answer to "How do you get something from nothing? was "Nothing is unstable." However he also stressed that you needed a pre-existing "framework" of laws to tell that 'nothing' to be unstable and what to do next.

    Basically Krauss' answer to the claim that it wasn't really nothing, you have to have a set of pre-existing natural laws that produced the universe "from nothing", was "the multiverse did it!" (See You think there's a multiverse? Get real thread)

    Krauss suggested that perhaps all possible laws exist and different sets of them give rise to different universes in the multiverse, (and of course we are in this one because we can be in no other).

    The problem is being able to test this idea and the question about whether its really science. I think its a bad way to do science but Krauss thought it necessary to avoid having to say some Being said "Let there be whatever...." .i.e. to avoid a "supernatural answer".

    If someone said that God said "Let there be light" (Genesis 1:3) then a justifiable response would be "Show me (provide testable evidence) of this God and I would believe you, the problem is you can't - you need faith"

    If someone (Krauss) said "Subsets of the set of all laws each produce different universes in the multiverse set of all universes" then a justifiable response would be ""Show me (provide testable evidence) of these other universes and I would believe you, the problem is you can't - you need faith"

    The question is "What are you prepared to put your faith in?"

    Which ever way, until testable evidence is found such answers protrude beyond the bounds of science. Certainly I would be prepared to put the multiverse and indeed string theory in the category of 'speculative science'; but such a qualification is necessary.

    Of course either answer does not solve the problem of origin, the questions "What was there before God?" or "What was there before the multiverse?" remain unanswered and perhaps unanswerable.

    Garth
     
    Last edited: Apr 4, 2015
  9. Feb 5, 2015 #8
    Hello everyone.
    Thanks for your input.

    I am slightly confused... Above, PeterDonis said that the article I referred to : http://arxiv.org/abs/1405.6091 is not really disproving Krauss' claims. I don't really know how he can say that. Although at least to me, Kohli is going through Krauss' arguments one-by-one, the main one seems to be argument #4 on page 4, "Claim 4: Krauss claims that “in quantum gravity, universes can, and indeed always will, spontaneously appear from nothing” [Kra12]."

    It is quite clear from this section, that Krauss' claim of a universe spontaneously appearing from nothing is false. Perhaps Kohli should've focused more on this point, as this seems to be the main point (not to mention the title of the book!). If the arguments in this section are correct, that indeed, Krauss' claims have been essentially disproven? Right?
     
  10. Feb 5, 2015 #9

    Garth

    User Avatar
    Science Advisor
    Gold Member

    Yes, whereas Krauss' claim that a closed universe dominated by matter and DM will collapse is usually true, there are cases when it is not.

    As far as the "something from nothing claim," we have already covered this point above.

    Kohli is saying the same thing as myself and the critics in the lecture Bandersnatch linked to: for "in quantum gravity, universes can, and indeed always will, spontaneously appear from nothing” the assumption is made that the Wheeler-DeWitt equations on which the theory depends "exist on some space, namely, this superspace/minisuperspace. In particular, for such a proposal to be considered as a valid physics-based proposal, it has to be at least in principle, testable. Namely, one would have to show that preceding the big bang, or the creation of our universe, that there really was such a superspace in existence. It is not clear how at the present time that we could even begin to consider how this could be accomplished".

    i.e. There must be some pre-existing structure as Wilczek pointed out in the discussion.

    Garth
     
  11. Feb 5, 2015 #10

    PeterDonis

    User Avatar
    2016 Award

    Staff: Mentor

    It's false if Krauss actually meant "nothing", as in "not even quantum vacuum". But as I and others have pointed out, in any pop science book or presentation, you have to use language that is imprecise. I'm pretty sure that by "nothing", Krauss meant "quantum vacuum", and that what he was describing was a universe spontaneously appearing from the quantum vacuum.

    You might say that is imprecise, or even misleading, language, but note that Garth gives a quote from the video Bandersnatch linked to, in which a critic of Krauss uses the word "nothing" with exactly the same meaning. So if that use of the word "nothing" is a problem, it's a problem with just about every physicist who uses layperson's language to talk about this subject, not just Krauss.

    It is certainly true that Krauss does not attempt to explain where the quantum vacuum came from, and in that sense the argument given in his book is clearly incomplete. But the article you linked to does not make that criticism.
     
  12. Feb 5, 2015 #11
    Hi. If you read the article by Kohli carefully, and actually see Krauss' book, he actually claims that "nothing" is no space and no time. So he even postulates beyond the quantum vacuum, as the quantum vacuum is certainly space and time.
     
  13. Feb 5, 2015 #12

    PeterDonis

    User Avatar
    2016 Award

    Staff: Mentor

    No, it isn't; that's the point. Remember that "quantum vacuum" here means vacuum states in quantum gravity, not vacuum states in ordinary quantum field theory (which is indeed formulated in a background spacetime). The whole point of quantum gravity is to figure out how to describe quantum states and figure out which ones are vacuum states (i.e., states of minimum energy) without a spacetime structure. Spacetime then becomes an emergent property of the underlying states (or some of them) in the quantum gravity theory.

    So when Krauss describes "nothing" as "no space and no time", he's talking about quantum gravity theories which are formulated without a background spacetime. Kohli's criticism is that even in such theories, there is still a "space" involved; but I think he's shifting meanings of the word "space". As he uses it, he means an abstract space such as the "superspace" in the Wheeler-DeWitt superspace formulation of GR. But Krauss was using the word "space" to mean our ordinary concept of space as part of spacetime. So Kohli isn't rebutting Krauss's argument on this point, at least as I read it; he's simply talking about something else.
     
  14. Feb 5, 2015 #13

    Chronos

    User Avatar
    Science Advisor
    Gold Member

    The rub in proposing a universe from nothing is in defining 'nothing'. Peter Donis and others have already eloquently covered that ground. It is certainly difficult to fathom what, or how, any 'law' could exert influence over 'nothing', which, at least philosophically, is utterly devoid of intrinsic properties. The quantum vacuum suggested by Krauss is a special case of 'nothing', which begs the question - what is it that fluctuates that is not an intrinsic property of 'nothing'?
     
  15. May 5, 2015 #14
    Yeah, Krauss is expert at "nothing". But, I like Larry. :smile:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Universe from nothing
  1. Universe from nothing ? (Replies: 11)

Loading...