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How Does Multiverse Theory Make *Every* Universe Possible?

  1. Jul 14, 2015 #1
    Is every combination possible based off of uncertainty? When the big bang happens in another universe and one electron moves slightly differently because of uncertainty it changes everything. Is that why there are "infinite" number of universes?

    When people say infinite do they really mean infinite? So is it actually true (if I were in another universe) that everything could be the exact same, but instead I'd be writing the answer to this question just because I figured it out before any one else on the world or does that have implications that would make the multiverse different in different ways?
     
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  3. Jul 14, 2015 #2

    bapowell

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    It is not known whether there are an infinite number of universes.

    In theory, however, it is often said that in an infinite multiverse, all possible realities play out. It's fun to imagine, say, two different universes with identical histories up until a particular point, when you suddenly decide to do something different in one of the universes. I think this is what you're getting at when you say "be the exact same". This is actually not possible if determinism holds. Sure, quantum uncertainty allows for identical pasts to have different futures, but there are limits: an electron might jump an energy level in one universe and not the other, but a human being won't suddenly decide to act differently because such macroscopic activities require a great number of quantum mechanical events over a relatively long time scale.
     
  4. Jul 14, 2015 #3
    I would argue that macroscopic events can be changed across the entire universe by even the influence of the gravity of the electron jumping a tiiiiny bit further due to chaos theory.
     
  5. Jul 15, 2015 #4

    bapowell

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    What does chaos theory have to do with quantum transitions?
     
  6. Jul 15, 2015 #5
    Not my scope of knowledge but I'd like to throw this in:

    I read a book on bubble theory, the theory that the there are a number of universes, surrounded by an event horizon out of which no universe can observe the others.

    Anyway, the author made a case for the differences in the universes occuring from variations of the fundamental forces after they separate. For example, in one universe, an instant after the big bang, matter and energy become distinct. An instant later, gravity, strong and weak nuclear force, and EM force become distinct. However in this universe, gravity is a fraction weaker than in ours, and so, theoretically, dust clouds never clump into planets or stars.
     
  7. Jul 15, 2015 #6

    bapowell

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    Yes, that kind of multiverse is particularly motivated by string theory (the so-called "landscape" of string vaccua) where each universe has different values of the fundamental constants. The string landscape, though embarrassingly vast, is not infinite.
     
  8. Jul 15, 2015 #7

    Any tiny movement in one area affects the entire universe. One electron moving a tiny bit differently changes everything in the universe. (wiki: "studies the behavior of dynamical systems that are highly sensitive to initial conditions")
     
  9. Jul 15, 2015 #8

    bapowell

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    Sure, but that's not the same thing as having two identical universes up to a particular point at which something suddenly occurs on a macroscopic scale in one and not the other. Quantum physics will cause macroscopic differences, but these will take time to manifest.
     
  10. Jul 15, 2015 #9
    I didn't say it wouldn't take time to manifest. Basically, my question is: Does multiverse theory claim that there are literally an infinite number of universes where I am a doctor in one that cures cancer and I'm a MMA fighter in another? Any wouldn't this mean there are a huge number of degrees of infinity?
     
  11. Jul 15, 2015 #10

    bapowell

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    Multiverse theories are highly speculative at this time (there is no "multiverse theory"), and so we have no idea what the physics of the multiverse is. If you wish to postulate that there are infinite number of universes, each with different initial conditions (different positions and momenta of all the particles) then, yes, there will be a universe where you cure cancer and one where you are an MMA fighter providing that neither of these is physically impossible.
     
  12. Jul 15, 2015 #11
    In some multiverse theory there is infinite possibilities with different physical properties.

    Weird for me as an atheist to accept. There could be a universe in which a God created everything in six days a few thousand years ago. As a paleontologist I'm am writing about it in that Universe with derision because it all seems silly.... however, in an infinite number of universes there could be....

    Yikes...gets too weird.
     
  13. Jul 18, 2015 #12
    Yes indeed, it does seem silly.

    I certainly won't be subscribing to any multiverse theories until someone puts some hard facts on the table. That doesn't seem likely with multiverse theory any time soon.
     
  14. Jul 18, 2015 #13

    ChrisVer

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    the quantum mutiverse is an interpretation of Quantum Mechanics, and as an interpretation it doesn't touch the physics of it (I know quantum mechanics in some good extend but I don't really care about the "multiverses") but it's a philosophical point of view. You can do quantum mechanics without getting involved in the different interpretations of it.

    The multiverse in string theory is a different thing, and it doesn't apply to different moments or "measurements". I think it was applied at the beginning of the Universe when it was supposed to be a "stringy"-theory governed thing. In strings (if someone believes that this is a real physical theory- I don't) I think you can derive the number of those extra universes that were 'born' together with ours (so it's a "prediction" -bad I'd say- and not an "interpretation")...and that's why to people who tell me that sting theory predicted our Universe, I return that it predicted it together with a vast number of different ones...if I recall well some people found ~10500 ones, together with ours.
     
  15. Jul 20, 2015 #14
    I say to those who tell us that string theory predicted our universe:

    No, because your models have 11 dimensions, whereas our universe only has 3.
     
  16. Jul 20, 2015 #15

    bapowell

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    There's more to it than that. String theory predicts that extra dimensions are compactified, making them difficult to observe directly.
     
  17. Jul 20, 2015 #16
    I know what it predicts and I know that the extra dimensions are 'compactified'.

    As I said, it is wrong because our universe has 3 dimensions.
     
  18. Jul 20, 2015 #17
    That's not a valid argument in physics.
    I too try to remain sceptic but don't start criticizing for the sake of criticizing.

    If you must point out flaws start with the absence of deSitter solutions.

    Also we live in a universe with 3 spatial dimensions. Not 3 dimensions altogether, 4 dimensions is what we work with since Einstein's GR.

    bapowell is correct (within the scope of string theory), the predicted size of these compactified (curled up) dimensions is (can be?) smaller than scales we can probe at this time.
     
  19. Jul 20, 2015 #18

    bapowell

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    How do you know that our universe has 3 dimensions?
     
  20. Jul 20, 2015 #19
    Every time I hear this 'curled up dimensions' I cringe. Show me evidence for this please.

    I know the universe has 3 dimensions because I exist in it.
     
  21. Jul 20, 2015 #20
    We don't have proof, we don't have prove against it either.
    Within the confines of science this means we cannot dismiss the theory as false!

    We keep with the theory because various reasons (this is my feeling about this).
    One will be senior scientists don't want to abandon a theory they spent a significant part of their life on.
    Another is the elegance of the theory (the idea is quite simple, the maths gets hard quite soon).

    The extra dimensions are there for technical reasons and really make our starting point simple. (for example 11D sugra contains a graviton, gravitino and a 3-form gauge field, not that much particles).
    The technical reasons are easy to see in modern books (I liked the treatment in Becker, Becker, Schwarz for bosonic strings).

    But as you say, we only perceive 3+1 dimensions so we have a surplus of dimensions.
     
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