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What's the nothingness that our universe is expanding into?

  1. Mar 24, 2015 #1
    We all know that the universe is expanding. What I'm curious about is what it is expanding into.
     
  2. jcsd
  3. Mar 24, 2015 #2

    phinds

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    It is not expanding into anything. The universe is everything there is. Either it is spatially finite but unbounded (no edge, no center) or it is infinite (no edge, no center).
     
  4. Mar 24, 2015 #3
    If the universe is all there is, what was present before the big bang ?
     
  5. Mar 24, 2015 #4

    phinds

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    Unknown. The Big Bang Theory has nothing to say about what came before one Plank time.
     
  6. Mar 24, 2015 #5
    Interesting :)
    Thank you
     
  7. Mar 24, 2015 #6

    wabbit

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    The answer is "that nothingness is nothing" :wink:
     
  8. Mar 24, 2015 #7

    Doug Huffman

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    @Meron

    Try reading some different interpretations of cosmology, in this case particularly Smolin's and Unger's that use principles of Charles Sanders Peirce.

    Space is used to describe separation and extent of entities. Where there is only one thing - the "singularity" - then there is no separation or extent. Similarly for time, time is used to describe change and duration. Where there is no change, then there is no time. Another thing and change both come from the singularity.

    (You may have a physics significant name-fellow, Matti Meron of UCI as I recall, with whom I used to correspond in the hey-day of Usenet.)
     
    Last edited: Mar 24, 2015
  9. Mar 24, 2015 #8
  10. Mar 25, 2015 #9
    I am C- caliber in trig and high school physics, and have been taught no math or science beyond them, but I speak 3 languages, am from a city (Miami) where Spanish replaced English for a while, and am descended from an ethnic group (the Irish) whose native language was permanently replaced by English. My impression is that a lot of the distinction between "space" and "nothingness" is shifting, due to the replacement of one "language" (spoken) by another (mathematical). (Notice how I typed "3", instead of "correctly" typing "three"? I did that without thinking about it, because math IS more concise for all kinds of expressions.) From a lot of reading (popularizations by several major physicists, and a bit of philosophy), I've tentatively concluded that it's quite important to notice whether a particular type of "field" can have a zero value or not, in deciding whether portions of it are considered to be at least potentially infinite spatially. It's also rather important to figure out whether diagrams (another potentially concise form of expression) are intended to depict abstractions (and are thereby analogous to, say, bus timetables) or have a closer resemblance to, say, a picture or map: These distinctions get very blurred by instructors trying to retain the attention of bored students, and the blurring has worked its way into the terminology at different times. The blurring has resulted in 21 interpretations of Mach's Principle, one of the ideas that inspired Einstein.
     
  11. Mar 25, 2015 #10

    wabbit

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    Linguistic differences do not matter much if at all in science.
     
  12. Mar 25, 2015 #11

    Doug Huffman

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    Perhaps, though, to the scientists. There is a spectrum of interpretations of QM.
     
  13. Mar 25, 2015 #12
    I agree that linguistic differences should have nothing to do with formulated science, but I'm saying that the conversion of mathematics into spoken language can change the personnel doing the formulation, and consequently change the accuracy or completeness of the science: I don't believe it's clear exactly which of the 21 reported versions of Mach's Principle influenced Einstein, and, if it had been, we might be having less of a problem with, say, singularities than we're having now.
     
  14. Mar 25, 2015 #13

    phinds

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    I don't get how any of that could have had anything to do with singularities. They are just places where the models break down. Are you saying that liguistic differences might have lead to a more complete theory that would not have places where they break down? I find that hard to believe.
     
  15. Mar 25, 2015 #14

    wabbit

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    I find it hard to imagine how you can ascribe a linguistic origin to singularities in GR, and I would be very interested if you could produce evidence for such a claim.
     
  16. Mar 25, 2015 #15

    wabbit

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    Indeed but do they depend on which language they are stated in? This can be true for philolosophy or poetry, which can defy translation, but Copenhagen or Everettian or other interpretations of QM do not seem to pose a problem of translation.
     
  17. Mar 25, 2015 #16

    Doug Huffman

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    No, not of translation but of nuance, subjective QBism on one hand versus a plethora of 'objective' interpretations.
     
  18. Mar 25, 2015 #17
    slatts said:
    I agree with Wabbit that linguistic differences should have nothing to do with formulated science, but I'm saying that the conversion of mathematics into spoken language can change the personnel doing the formulation, and consequently change the accuracy or completeness of the science: I don't believe it's clear exactly which of the 21 reported versions of Mach's Principle influenced Einstein, and, if it had been, we might be having less of a problem with, say, singularities than we're having now.

    Phinds said:
    I don't get how any of that could have had anything to do with singularities. They are just places where the models break down. Are you saying that liguistic differences might have lead to a more complete theory that would not have places where they break down? I find that hard to believe.

    Slatts' reply to Phinds is:
    In my reply to Meron's post, I was "drawing" an analogy between spoken-and-written "language" per se, and mathematics per se. In my own reply to Wabbit's, I was saying that the conversion of mathematics into spoken/written "language" could, if not done carefully, discourage people like Meron from interesting themselves further in physics, or at least alter the subjects of interest to them. Mach's Principle was attributed to Mach only anecdotally, since he had not given it any notation in physics or math, but Einstein was well enough aware of it that he wrote Mach of some partial confirmation of it which he (E.) was proud of having accomplished experimentally. Since Mach's Principle had to do with the tendency of our arms to rise when we spin around under the stars, it's generally felt to have had to do with a gravitational influence exercised by distant inertial fields. I suspect that Gödel's solution of a rotating universe resulted partly from the well-known knowledge of Einstein's interest in whatever principle was involved. I'm speculating that, if we had known exactly which of the 21 written formulations of Mach's Principle were eventually devised, we might have eliminated singularities from physics years ago, which would have left Hawking free to accomplish even more useful work than he already has, during the time he wasted making bets with Kip Thorne. (This is WAY more speculative than I want to be, but I'm responding to your own reply.)

    About the possible disappearance of cosmological singularities from physics (which I hadn't been trying to discuss in this thread), google Ali and Das' "Cosmology From Quantum Potential", written in Dec. 2014. (Not to add to the confusion, I have to mention that, although Ali and Das' reformulation of General Relativity into QM doesn't refer to singularities in particular, their elimination seems--per Bojowald and Rovelli--to be a main aim of Quantum Mechanics, whose control of tiny details does not seem to tolerate the arrival of huge amounts of reality from nowhere very well.)
     
    Last edited: Mar 25, 2015
  19. Mar 25, 2015 #18

    DaveC426913

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    Dude, use the quote feature in the editor. :wink:
     
  20. Mar 25, 2015 #19
    Thanks, it seemed to work OK this time, although I had to use the .<< edit >> option to add this comment.
     
  21. Mar 25, 2015 #20
    Thanks. I'm just realizing that, in my last reply, it had shown my last quotation of myself after my quotation of the other guys and before my quotation of myself. Pretty smart of it.
     
    Last edited: Mar 25, 2015
  22. Mar 25, 2015 #21

    DaveC426913

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    The usual method is this:
    Instead of starting with the editor, start with the post(s) you wish to quote.
    In the bottom right corner of each post (so posts 10, 13 and 15), there is a [+ QUOTE] button. It's a multi-quote feature.
    Click it once on each post. They will accumulate.
    Now, at the bottom of the page, where you want to Reply, you'll see under the editor a [INSERT QUOTES] button.
    Click that, and your posts will be inserted automatically into the reply. (Don't forget to pare the quoted text down to the essentials.)
    Now you can add your comments at-will.

    quotes.jpg
     
    Last edited: Mar 25, 2015
  23. Mar 25, 2015 #22

    phinds

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    I still think you are way off base in thinking that linguistics or different formulations would have had any effect on singularities in our models. I don't think you understand what singularities are. What DO you think they are? How do you think anything you have talked about would have mattered to getting rid of them by formulating better theories than we have now?
     
  24. Mar 25, 2015 #23
    Like I say, you and I are in a speculative discussion, but I guess it's not a speculative THEORY of PHYSICS, so I guess it's marginally OK per the Forum's rules. (It's absolutely fine with me, and maybe you can advise me on whatever physics terminology I'm using incorrectly.)

    I think a singularity is a near-convergence of geodesics at a point in spacetime a little above the Planck scale. Since they're not allow to cross or turn at a sharp angle under its rules, it is the place where relativistic physics does, like you say, break down. As recently as a week or two ago, I had thought, "So what?" After all, for many years the Big Bang had been regarded (mostly because of its improved correlations with chemistry) as a major improvement over Hoyle's steady state theory. As far as physics is concerned, it's my understanding that they are actually similar, and, like inflation (whose sequencing with, or redundance upon, the Big Bang is very unclear to me), both allow for a universe to form with a net expenditure of energy that's at or near zero, through a release of energy from its potential upon the expansion of a gravitational field, which I've heard is negative energy in both its attractive and its repulsive varieties. The Big Bang resolved a very obvious paradox (Olbers') in a very simple way, and I had loved the idea of it for many years.

    The problem, which I was largely unaware of until I finished plowing my way through a popularization by Bojowald, is with information theory. As you can see by poor Dave's having to lead me by the hand through a "rather mild" algorithm just now, I'm about as lame on information theory as can be, although I've heard it has a lot to do with entropy. (My only take on entropy is that Boltzmann must've committed suicide out of boredom, but I know it's really big, especially now.) Where this gets into Quantum Mechanics, and why I was suggesting you might like the QM/Relativity synthesis suggested by Ali and Das, is that QM does not allow information to get lost, so, while it's achieving its miraculously accurate (and technologically important) predictions by tracking every path every particle even might take, it's not happy with a whole starload of details suddenly leaving the premises. I know it evaporates in an eon (our time), and that a 2D version of it may remain plastered over the poor star's event horizon meanwhile, but the string theory governing that plastering has about as much fire in it as an ice sculpture of a well-digger's belt buckle floating halfway between us and Andromeda. THAT's why I think you might enjoy Rovelli's "Planck Stars" and the Ali-Das essay.
     
  25. Mar 25, 2015 #24

    phinds

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    I have no interest in being in a speculative discussion. We are talking past each other.
     
  26. Mar 25, 2015 #25
    Actually, I forgot to rehash what was speculative (about the effect of imprecise language on the inspiration of prospective physicists), but it was just psychological or literary speculation anyway.
     
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