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What have happened with other possible variants of asymmetry?

Are there other universes being run in parallel to our universe where the ball is not at C, but at B?

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Stephen Wolfram told

I have found some basic principles that are even more basic than principles of our universe itself. These principles allow to generate many universes. One of such universes is very similar to ours.

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and this reminded me about "symmetry". What do we expect will happen in future?

  1. we will prove that the "other 11 variants of universe" have mistakes and that "there is only one universe possible, that is our universe"

  2. or we will prove that other variants are possible and we will reach them or create them. (just like David Deutsch tells "we will use the computational power of computers from other universes".)

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    $\begingroup$ What symmetry? Which references? Which pages? $\endgroup$
    – Qmechanic ♦
    Commented Jun 25 at 5:51
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    $\begingroup$ By definition of the word universe? No. $\endgroup$
    – FlatterMann
    Commented Jun 25 at 6:53

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In classical physics there is only one history and symmetry breaking is understood in terms of saying that any particular system is very unlikely to perfectly respect the symmetry even if the probability distribution does respect that symmetry.

In quantum theory that hasn't been modified to include collapse, interference is suppressed when information is copied out of a system: decoherence. This can happen as a result of conservation laws which prevent histories with different values of the conserved quantity from interfering:

https://arxiv.org/abs/0903.1802

Conservation induced decoherence results in decoherent histories for each sector:

https://arxiv.org/abs/1808.09547

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I'm not an expert in quantum field theory or string theory, but as I understand it, these "other universes" have different laws of physics (in the low-energy limit). At some very high energy (point A in the figure), then every universe is governed by string theory, but at lower energies (points B and C) you get different laws. If points B and C don't have exactly the same energy, then it's in principle possible for the universe to quantum tunnel from the local minimum to the next-local minimum,* which would destroy the universe as we know it.

If this picture of the universe is correct, then because dark energy is a positive energy density right now, then our universe is almost certainly not located at the global minimum. This means we can indeed quantum tunnel to another universe, and over some impossibly-long timescale it'll inevitably happen.

That said, I stress that all this is highly, highly speculative.

*As long as that minimum has a lower energy than the original

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I think, since we can only study the physics of this universe, this question counts as meta-physics. Our current theories allow us to describe the reality that we see, and that's all that we need.

As with most quantum mechanics, you could ask the question: Suppose you have a superposition of states A and B. If we measure the state and find it's in A, is there a parallel universe where it's in B? This is akin to asking what interpretation of quantum mechanics you subscribe to, which is a matter of opinion, since all interpretations give the same outcome. The answer is - we don't know, we can't know, and it doesn't matter. Since all that physics (especially cosmology) aims to achieve is study this universe, what happens outside is someone else's problem.

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  • $\begingroup$ A superposition in quantum mechanics is a property of the quantum mechanical ensemble. That's a mathematical abstract. It does not exist in reality. So, yes, we do know. It's simply a misuse of the theory to talk about superposition in this way. $\endgroup$
    – FlatterMann
    Commented Jun 25 at 6:55
  • $\begingroup$ I think you've misunderstood my point. This is the essence of what I was getting at: you can consider that the superposition be real, or simply a mathematical necessity. You cannot, by means of experiment, determine whether it is real or is just part of the mathematics. Which means that it is metaphysics, thus arguing over it is obsolete as it does not affect observables whether it is really real, or just maths. You opt to believe that it is just mathematical. But you must concede that since the discussion is metaphysical, you cannot assert your view is correct. $\endgroup$
    – Chaddyfynn
    Commented Jun 26 at 7:10
  • $\begingroup$ My point is that one can not consider the superposition real. We know how the theory was constructed. It can be structurally derived from a physicists version of Kolmogorov's axioms with fairly little effort and one can find experimental examples where a naive application of quantum mechanics does not work because the actual physical measurements are not independent, i.e. a measured time series is not equivalent to an ensemble. There is no metaphysics here. Linearity of the theory follows from statistical independence and that assumption can (and has to) be verified experimentally. $\endgroup$
    – FlatterMann
    Commented Jun 26 at 7:51
  • $\begingroup$ The more important application of the opposite, i.e. when consecutive measurements on the same system are not independent but highly correlated is, IMHO, the Mott problem. It derives the "particle tracks" that occur in high energy physics detectors from wave mechanics: Mott "The wave mechanics of ∝-Ray tracks" Proceedings of the Royal Society of London. Series A, 126 (1929). The paper is the first fully worked out example of weak measurement theory/decoherence as far as I know and is the prime example of the actual quantum-classical transition. $\endgroup$
    – FlatterMann
    Commented Jun 26 at 7:59

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