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How can the Universe be infinite and there be an infinite number of Universes?

  1. Jan 3, 2013 #1
    I've seen a lot of programs about M Theory and string theory and such which suggest that there could be an infinite number of infinite universes in this multiverse. And according to microwave background radiation our universe is infinite.

    But how could there be an infinite amount of infinite Universes? Wouldn't there have to be a boundary for each of these Universes? If one Universe is infinite and never ever stops, how could there be an infinite amount of universes that never stop?

    Sorry it's my first post but this really confuses me after all these shows I watch on BBC and stuff.
  2. jcsd
  3. Jan 3, 2013 #2
    Take a plane. Look at the lines y=0, y=1, y=2, etc. These are all infinite 1-dimensional Universes, and there are an infinite number of them.

    Which isn't to say this is the only way (after extending it to 3-dimensional Universes in 4-space, of course.)
  4. Jan 3, 2013 #3


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    This is not a correct conclusion to draw from the CMB. Where'd you hear it?
  5. Jan 3, 2013 #4
    Science channel "How Big is the Universe?"

    A guy named Sean Carol and Saul Perlmutter and the narrator said it toward the end of the show.
  6. Jan 3, 2013 #5


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    There was a BBC 50 minute episode on "Horizons" with Saul Perlmutter, David Spergel (highly reputable) and Sean Carroll (half into pop-sci and media, but the other half very good.)
    this was called "Horizons: How big is the universe?"

    No respectable scientist can say with certainty that the U is infinite, or that there are an infinite number of them. That's silly. So if you listen to the show again, I doubt very much you will hear either Perlmutter or Spergel actually say that.

    The actor who serves as anchorman/interviewer on a Telly series will often lie, mislead, bend the truth (to make it sound good to audience, or out of sincere misunderstanding). You can't trust wide-audience science media. Telly seems especially unreliable.

    It's OK to GUESS or SPECULATE about infinite or infinitely many, or say ALMOST FLAT and therefore possibly VERY BIG. But very big is not infinite, and almost flat is not flat. But to be fair to the audience you have to qualify and say "maybe" and "we don't know for sure".

    I don't watch pop-sci television but I saw a transcript of part of what Perlmutter said. It was excellent. It was talking about the 1998 work of his team. The supernova standard candles, the distance measurement, the discovery of this slight acceleration which acts like a constant term in the Einstein equation. The SURPRISE of it. Janna Lewin commented that she did not believe it at first. This part is good journalism. It is not speculative. It is real science history about real discovery. Great. But that part said noting about infinite universes and speculative maybe-land.
  7. Jan 9, 2013 #6
    I'm not quite sure what you aren't understanding? There certainly can be an infinte number of Universes and some of these Universes might be infinte and others might be finite. Nobody knows for sure though.
  8. Jan 29, 2013 #7
    I will first frame my response by acknowledging that I am aware that philosophical speculation is somewhat frowned upon here. I come here mostly just to browse and better aquaint myself with the thinking shared by the more hard science minded. I think the 'stick to real science' policy serves this forum well in that it serves to protect the forum's integrity and keep out the woo woos. I still miss the philosophy forums, but i get my fix for that elsewhere.

    Disclaimer: I'm just a librarian armed with a curious and inquiring mind.

    Regarding your question then, Ben, I think a telling approach might be a reframing of your query. I propose asking instead, "How can all that is not be infinite?" or "How would it be possible for there to be a boundary to all that exists?" It's a case of there not really being a way to rationally get around infinite causal regress. In order to deny actual infinity one must posit a beginning and bounding limits to actual reality. We concede, of course, that reality is limitted in the one sense to what is actually possible and that what is actually possible is circuitously restricted by actual reality. One would necessarily, both epistemologically and in order to account for actual reality, have to posit something from nothing.
    No. Don't worry. I'm not going there.
    Without getting too far into the semantics surrounding 'nothing', if we wish to account for anything and accept that absolute nothing represents a state wherein there are no degrees of freedom whatsoever, then nothing could not in any way be anything other than nothing. There would be no possibility of anything ever being able to come from nothing as there would be nothing that could undergo change in order to become something other than nothing.
    Given that we must accept the simple tautology that existence exists, then existence must necessarily have derived from prior something, and that something must necessarily have been sufficient to account for what actually is.
    One could posit that all is static and that change does not occur, but i'm not suggesting that we go down that dark path either.
    No. I don't think this calls for any supernatural explanations either. I'm not contortionally twisting my thinking or yours to go in that direction. Not to worry.
    Nothing suggests or necessitates positing anything 'outside' since we cannot rationally have anything beyond all that exists. That would imply a boundary again and boundaries can only frame finite, localized entities within the necessarily always greater all that is - which, again, would have to be actual infinite reality.

    I do understand that there cannot be observational confirmation that existence must be infinite. It comes down to determining what must be the null hypothesis is this regard. It would seem that since all that has ever been observed has been observed within greater spacial, mathematically modeled or epistemologically constructed contexts, and within always greater causal/temporal reference frames, then reality would seem to be implied by infinite causal regress to be infinite.
  9. Jan 29, 2013 #8
    As much as I enjoyed that post I had one problem with it. The problem is what is often described as nothing is often looked at as a vacuum. There is a theoretical model of existence from nothing. This model details a process of Heisenburg uncertainty. Coupled with virtual particles etc etc. Lawrence R Krauss has written one book on this model. I also have a few articles on it if your interested.
    I prefer to use the term nonexistant in this usage of describing outside the universe boundary.
    Another point a poster mentioned on a recent similar thread is that if you can devide infinity an infinite number of times each devision will still be infinite. The various models of cyclic univereses is that they cannot answer Where the first universe started. Same goes for the BH universe models that their is a universe inside every BH. Several problems arise in that model. One BH s don' t have consistent feeding rates so there should be perturbations. Our universe is too evenly distributed and their is no indications of those fluctations.
    The big bang is often described as starting from infinite in size but infinite density. In other words never
    finite in size. Thank fully the big bang model is only describing the inflationary cycles. The point at which inflation starts. As we have no evidence or observations of another universe this is the best approach.
  10. Jan 29, 2013 #9


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    Marcus, I think you are overly optimistic about what these guys say on popularization TV shows. I appreciate what you are saying about them as knowlegeable and I know that they are but I am certain that I have heard Sean Carrol (Spergel ???) say things that I KNOW he knows to be wrong because I've read one book by him and have a set of lecture tapes by him on Dark Matter / Dark Energy. I find him entertaining and very knowledgeable despite the TV nonsense.

    I haven't seen enough of Perlmutter to remember having heard him do it, but certainly I've heard silly statements from Carroll, Lawrence Krauss and numerous others. By "silly" I mean things that I am SURE they know are wrong, or at the very least incredibly poorly worded. For example, I've heard several of them say that the universe started by exploding from a point. In fact I'm pretty sure that's one of the things that Carroll said.

    Why they all seem to do this I don't know, but I've seen it over and over. I hypothesize that part of their contract to do these shows is that they turn their brain off and talk on autopilot.

    And I'm not even counting here all the times I've heard, I think ALL of them, creating seriously false impressions by using the term "universe" when they clearly mean "observable universe".
  11. Jan 30, 2013 #10
    In not just tv, how many cosmologists have said that as fact there was no time or space beforew the big bang ?
    BUt I agree the biggest misleading statement cosmologists make is not differentiating between universe and observable universe.
  12. Jan 30, 2013 #11
    I think my all time favourite is that information is not lost when it enters a blackhole. Its sent to a universe that has no Blackholes. This was a pop media coverage of Stephen Hawkings/Penrose argument
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