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Space Science

Why We Think There's a Multiverse, Not Just Our Universe 458

Posted by Soulskill
from the because-the-drake-equation-needs-another-term dept.
An anonymous reader writes "It's generally accepted that the Universe's history is best described by the Big Bang model, with General Relativity and Quantum Field Theory as the physical laws governing the underlying framework. It's also accepted that the Universe probably started off with an early period of cosmic inflation prior to that. Well, if you accept those things — as in, the standard picture of the Universe — then a multiverse is an inevitable consequence of the physics of the early Universe, and this article explains why that's the case."
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Why We Think There's a Multiverse, Not Just Our Universe

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  • You mean (Score:3, Funny)

    by deodiaus2 (980169) on Saturday January 11, 2014 @09:09PM (#45929269)
    That there is a universe out there where Sarah Palin is President.
    • Re: (Score:2, Informative)

      by Anonymous Coward

      That universe was destroyed by the Living Tribunal as Too Stupid to Survive.

    • on tonight episode of sliders

    • by anagama (611277)

      Call in Fraa Jad -- he can fix it.

    • Sorry that you got modded Flamebait. If it makes you feel better, all other universes modded you +5 Funny.

    • Re:You mean (Score:5, Funny)

      by rudy_wayne (414635) on Sunday January 12, 2014 @12:24AM (#45930089)

      However there is no universe where Java isn't a piece of crap.

  • by gestalt_n_pepper (991155) on Saturday January 11, 2014 @09:16PM (#45929307)

    But the turtles appear out of nowhere and are very far apart.
    Why do cosmological theories of any merit always sound like they were written by Douglas Adams?

  • by JoshuaZ (1134087) on Saturday January 11, 2014 @09:16PM (#45929309) Homepage
    Note that this isn't talking about the quantum mechanical multiverse where whenever a decoherence occurs you get branching of different copies. This is talking about a more concrete notion of multiverse where the early inflation spreads out so much that there are lots of little regions of observable space time which cannot observe each other.
  • by Anonymous Coward on Saturday January 11, 2014 @09:18PM (#45929329)

    or something less stupid, instead?

    It doesn't make any sense to say that it's one big thing, but not one big thing at the same time.

    Kind of like saying it's not one big cake sliced into wedges, it's lots of little cakes that have nothing to do with each other.

    AND YET THEY OCCUPY THE SAME PLATTER.

    • by zAPPzAPP (1207370) on Saturday January 11, 2014 @09:38PM (#45929451)

      The problem lies in the name 'UNIverse'.
      You can not name something universe and then have something next to it.

      • You can name something 'university' and have another university next to it. Why not the same with universes. Both words come from a Latin expression that meant something like 'turned into one' or maybe 'rolled into one'. A 'university' was a sort of guild as in a guild of students, or students and teachers. Universe was probably meant to imply 'the whole deal' all of existence when it was first applied, just as 'the world' suggested there was only one world. Now 'the world' is 'our world' as opposed to

      • by craznar (710808)

        No more bizarre than naming something an atom, then dividing it.

    • or something less stupid, instead?

      It doesn't make any sense to say that it's one big thing, but not one big thing at the same time.

      Kind of like saying it's not one big cake sliced into wedges, it's lots of little cakes that have nothing to do with each other.

      AND YET THEY OCCUPY THE SAME PLATTER.

      Yes, and we call that platter... the multiverse, so we can discuss the cake we inhabit. Which is quite moist and delicious, by the way.

      Get used to it.

    • Observable universe (Score:5, Interesting)

      by Dan East (318230) on Saturday January 11, 2014 @10:55PM (#45929789) Homepage Journal

      I thought there were already concise terms for it. The universe IS the multiverse / partitioned universe. The part that we are in is called observable universe.

    • by quenda (644621)

      It doesn't make any sense to say that it's one big thing, but not one big thing at the same time.

      Why not? Its been working just fine for Christians since the 2nd century with the Trinity. Call it a Holy Mystery of the universe.

    • AND YET THEY OCCUPY THE SAME PLATTER.

      That's the key, it's different platters. One cake may have eggs and the other doesn't have eggs. Or, in the universes theory, one may have gravity as we understand it, and another may have it slightly different, or not at all. Certain realities about our universe, like the distance of a circle's diameter to it's radius, may be different in other universes.

      We cannot understand how this could actually be so, seeing as how we live in this universe, but the mathematical properties at their roots, could be

  • Words, words (Score:5, Interesting)

    by mbone (558574) on Saturday January 11, 2014 @09:33PM (#45929419)

    I think that this is a great article, but...

    It is obvious that there are parts of the universe that are not (and never have been) causally connected with our universe.Those are just the parts of our universe we can't see, which are inevitable in an infinite universe with a finite duration and a finite speed of light. You don't need either quantum mechanics or inflation for that, and it has never been called the "multiverse."

    The multiverse in my experience means exclusively the idea that there are other parts of the universe with different physical laws. That idea is connected to the anthropic principle, and (IMHO) evading tough issues about the nature of physical laws. (Find the cosmological constant to be inconveniently small? That's OK! In a multiverse there are a gazillion universe with large cosmological constants and no life like ours, ours with a small one and our kind of life, and nothing left to explain!) "We" might think that there is that kind of multiverse, but "we" in this case decidedly does not include "me." (People like me tend to call such ideas "Just so stories," which in physics is an insult.)

    • Re:Words, words (Score:5, Insightful)

      by Derec01 (1668942) on Saturday January 11, 2014 @10:23PM (#45929667)

      I disagree that he's only defined causally disconnected regions; this story actually has a definition of multiverse beyond regions outside of our lightcone. Note one of his later images: a single level 1 universe contained multiple regions which are not causally connected yet are part of the same clump that moved from the false vacuum to dumping energy into matter and radiation.

      Any grouping like that is fundamentally isolated because the boundary region that remains in the false vacuum continues to exponentially expand, quickly isolating the clump. Even if the clump itself triggers a conversion of the false vacuum around it, it sounds like the isolation proceeds so much faster that it will be forever isolated by expanding false vacuum regions. With time, we could reach places that are not currently causally connected. It doesn't sound like we could overcome this expansion so easily.

  • My God... (Score:5, Insightful)

    by jeffb (2.718) (1189693) on Saturday January 11, 2014 @09:39PM (#45929459)

    I know it's karma suicide to post on something like this saying "I don't get it", but, well, I don't get it.

    I've been reading about inflation, multiverses, and whatnot for a very long time at this point, and I like to think that I can give a reasonable explanation comprehensible to nontechnical people. I've come across some articles that were a lot of work to get through, and I've given up on some because I don't have the necessary math.

    But this article was terrible. Its grammar is good and not overly complex; it doesn't use a lot of obscure words. It's written like a nice popularization piece, with important parts called out in bold and lots of illustrations. But the illustrations are baffling -- what's that "getting closer to a sphere" four-panel diagram credited to Ned Wright, and where does the text refer to it? What the heck is going on with those diagrams from Narlikar and Padmanabhan? What's with the black space-balls rolling around on the mini-golf course at the end?

    I'd wonder if this is a Sokol-type troll, but I don't see anything obviously wrong in it -- there's just a bunch of stuff there that looks like explanations, but apparently isn't. Or maybe I'm just having a bad night.

    • Re: (Score:2, Insightful)

      by manu0601 (2221348)

      The problem is that this is not science: the theory does not predict anything, and no experience can be done to test it.

      In other words, this is faith. Faith is not bad, but there is always something wrong when you confuse it with science.

      • Re:My God... (Score:5, Insightful)

        by JoshuaZ (1134087) on Saturday January 11, 2014 @10:24PM (#45929673) Homepage
        There are tests for inflation. Depending on the version of inflation in question one can get different predictions, but one major issue is how close to flat the universe is. Another major aspect is the exact behavior of the cosmic microwave background. Study of these issues are both ongoing.
        • Re: (Score:3, Insightful)

          by manu0601 (2221348)
          I was referring to the multiverse part. You are not going to find a test about the existence of something which definition is that it cannot be observed.
          • Re: (Score:3, Insightful)

            by JoshuaZ (1134087)
            So, you have a testable set of hypotheses. Those hypotheses have non-testable consequences also. Calling those consequences "faith" seems off. For example, consider the following hypothesis "Every state is majority hydrogen." Now, there are stars which are in the process of disappearing from our future light cone due to the expansion of space. This hypothesis which we can get a lot of evidence for also implies that those stars are majority hydrogen. We will never be able to test that. Does that make that co
          • by Artifakt (700173)

            This version gets much closer to testable than the usual multiverse model. (The stock multiverse starts with an assumption that certain physical constants must be random - that's pretty much as untestable as saying those same constants cannot be random and must have been chosen by something). Unlike that, this version seems to be edging into the area of testability, at least in part.
            We can test some of the predictions of the various inflationary models, to fine tun

      • Re:My God... (Score:5, Interesting)

        by boristhespider (1678416) on Sunday January 12, 2014 @06:59AM (#45931159)

        +5 Inisghtful?

        "the theory does not predict anything,"

        Wrong.
        1) The universe is close to flat
        2) Regions that are currently causally disconnected were connected in the past - implying that both sides of the sky can exist at the same temperature
        3) There are unobservably few magnetic monopoles even if such monopoles can exist
        4) The primordial power spectrum of cosmological perturbations was almost, but not quite, Harrison-Zel'dovich
        5) There is a relic background of primordial gravitational radiation
        6) There is very litte primordial vorticity; observed vorticity has arisen through later processes
        etc.

        1, 2, 3, 4 are observably verified, by such experiments as COBE, Boomerang, WMAP, Planck, 2dF, SDSS, WiggleZ and their like. 5 is likely to be verified or rejected in the next year or two. 6 is currently very safely within bounds and looks far the most sensible explanation.

        "no experience can be done to test it."

        Wrong, though arguable if you insist on "testing" rather than "observing". In this context they're the same thing -- make a theory, make a prediction from said theory, and then find an observation to test it. For instance, ekpyrosis is likely to die in the next year or two since it predicts zero primordial gravitational radiation. But if you want to wank about definitions of words (which in my experience has been the practice of those with limited education in the field) be my guest; you can certainly argue it can't be "tested", even while the professionals are, um, testing the theories.

        "In other words, this is faith."

        No it is not. It is founded on a pair of solid theories -- general relativity and quantum mechanics -- and on a method of tying aspects of those theories together. The limitations are well known and well explored and the techniques are mathematically solid. Whether the physics is being applied the right way is a totally different question, but that's a matter for experiment and observation to determine, not one of "faith". I'm not suggesting for one moment that too many cosmologists haven't been educated into a theory that is far shakier than they believe, because they have, but even that isn't faith. It's merely a sign that we're overspecialising our cosmologists... and that there are no credible alternatives anyway, including from the likes of myself who have attempted to pursue fundamental issues at the heart of cosmology. A "credible alternative" explains all the data at least as well as a standard inflation+dark energy+cold dark matter big bang cosmology. There is a hell of a lot of data, and LCDM fits practically all of it remarkably well. Can't say that for almost any alternative.

        "there is always something wrong when you confuse it with science"

        No argument from me here, but it's not me getting confused.

    • by Kjella (173770)

      I'd wonder if this is a Sokol-type troll, but I don't see anything obviously wrong in it -- there's just a bunch of stuff there that looks like explanations, but apparently isn't. Or maybe I'm just having a bad night.

      Don't worry, science is ridiculously poor at describing singular events. The creation of the universe is - as we know it - a singular event. That life - and indeed moderately intelligent life - exists on this planet is yet another singular event. It can't be reproduced and so far we've got no evidence that life exists anywhere outside Eartn. Until proven otherwise we might still be the only living thing in all of Creation, though I wouldn't put my money on that.

      • I wasn't talking about the science, I was talking about this particular article's attempt to explain it. Which, in my opinion, was a terrible failure, regardless what I may think of the science itself.

  • I guess that's ok (Score:5, Interesting)

    by trentfoley (226635) on Saturday January 11, 2014 @09:42PM (#45929493) Homepage Journal

    I mean, I can handle the concept... so long as there's just ONE multiverse.

  • Because this probably means that somewhere there is a universe where desperation is considered sexy and Slashdotters are studs.

  • by Arker (91948) on Saturday January 11, 2014 @10:02PM (#45929571) Homepage

    But in this world the link leads to nothing but a teaser blurb and an invitation to blindly execute whatever arbitrary code another server might decide to hand me. No thanks.

  • If you remember a bit of calculus, you right appreciate the idea presented here. This one postulates that time varies according to Mass. We already know that black holes slows down time so...

    https://www.youtube.com/watch?v=oy47OQxUBvw [youtube.com]

    Even if you think this guy's a crack pot, it damn interesting.

  • The universe is, by definition, EVERYTHING. Therefore, there is no multiverse. There is an array of visible areas. TFTFY.
    • by quenda (644621)

      The universe is, by definition, EVERYTHING. Therefore, there is no multiverse.

      No, that doesn't even make one proper definition, let alone all of them. What is "everything" ? You probably end up with a circular definition.
      You need to start by defining "existence", which is not trivial.

      In TFA, multiverse refers to contiguous space-time, but there are many other uses of the term, e.g. Many Worlds Interpretation.
      Our "universe" is now detached if I understand correctly? But was connected to these other universes in the early days (nanoseconds?) of the big bang?

      • 1. I did not discuss "existence". The only verb I used was "is" and it was in the sense of "equivalent", as in everything = universe and universe = everything. So, we can dispense with your trivial philosophy right there.
        2. "In TFA, multiverse refers to contiguous space-time, but there are many other uses of the term, e.g. Many Worlds Interpretation." And that is the problem, right there from the getgo. When they came up with "many worlds interpretation" they trivialised the universe, and abused its defini
  • Misleading summary (Score:5, Informative)

    by SoftwareArtist (1472499) on Saturday January 11, 2014 @11:33PM (#45929893)

    It's generally accepted that the Universe's history is best described by the Big Bang model, with General Relativity and Quantum Field Theory as the physical laws governing the underlying framework.

    No no no. It's generally accepted that each one of these theories taken individually is the best currently known description within its particular domain. It is not generally accepted that you can just throw them together and get an accurate description of the fundamental nature of the universe! In fact, we know you can't do that because general relativity and quantum field theory are deeply incompatible with each other. People have been working for half a century to find a single consistent theory that can reproduce the predictions of both. They've made a lot of progress, but we're still a long way from having any confidence about what the true fundamental theory is.

    The picture of eternal inflation described in this article is plausible based on what we know. But it's still very speculative. That's true of any discussion of cosmology. Our current knowledge is just way too limited to have any confidence about it.

  • by Charliemopps (1157495) on Saturday January 11, 2014 @11:49PM (#45929943)

    Why do we always try and segragate things like this? We seem to have some need to put everything in it's own little box. Atoms, molecules, planets, solar systems...

    The definition of "Universe":
    all existing matter and space considered as a whole; the cosmos.

    So, if there is no need for the term "Multiverse" The universe contains it all. Our universe is just a tad more complicated than we had assumed.

    • by Livius (318358)

      And as soon as we're sure what 'existing' means, there'll never be confusion again!

    • We seem to have some need to put everything in it's own little box. Atoms, molecules, planets, solar systems...

      The definition of "Universe":
      all existing matter and space considered as a whole; the cosmos.

      So, if there is no need for the term "Multiverse" The universe contains it all.

      Definitions change with time. Once upon a time the Earth was the universe, until people decided that the stars weren't just stuck up like a sheet in the Earth's sky.

      Makes sense to have moons orbiting planets in planetary systems, orbiting stars in solar systems, orbiting galaxy centres in the galactic plane, orbiting super structures (Great Attractor, etc.), and finally you reach a boundary that is the "edge of the universe" with the current laws of physics that we know and love. If this universe is formed

  • If you took the time to read the article; Google: "dark matter" "vacuum energy"
    and see where it takes you, it's an interesting ride.

    FTA: "The ideas that you hear—multiple false vacua, the landscape, connections to quantum gravity, etc.—are ones that people have speculated upon in recent years. These are mostly driven by including connections to string theory, and they present a whole host of difficulties as well as a great many interesting avenues to investigate. I will not touch upon them here

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