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Tunneling to a lower energy vacuum state

  1. Apr 2, 2013 #1
    I read that the mass of the Higgs boson is such that we may be living in an unstable vacuum state, and if a region of the universe tunnels to a lower energy vacuum state, and eventually the whole universe would be in that lower energy state (ending life on earth).
    Do physicists have guesses about what the laws of physics would look like in a lower energy vacuum state? Is it possible that rest mass would disappear?
    thanks
     
  2. jcsd
  3. Apr 2, 2013 #2

    Bill_K

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    Everybody likes a good ghost story! And now that the LHC failed to swallow the Earth, and the Mayan calendar turned over without a care, we need something else to worry about.

    The serious question is to understand better why the Higgs mass puts it in the region of metastability. Here from the Résonaances blog is a good discussion on vacuum stability, and a relevant quote:
     
  4. Apr 2, 2013 #3
    I'm not worried about it, I hope that rest mass could go away, if the vacuum tunneled to a lower energy state.
    The link you gave doesn't say what might happen to physics.
     
  5. Apr 2, 2013 #4

    Bill_K

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    The link says it ain't gonna happen.
     
  6. Apr 2, 2013 #5
    That's not what they're saying more recently. Apparently with a more exact idea of the Higgs mass, the vacuum is metastable (could tunnel to a lower energy state).
    Again, I'm not asking whether this is likely to happen anytime soon.
    Even if it takes a googol of years to happen, I'm still wondering - if the vacuum tunneled to a lower energy state, could rest mass disappear?
     
    Last edited: Apr 2, 2013
  7. Apr 2, 2013 #6

    Bill_K

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    lark, Did you actually read the link I gave?? The argument that our vacuum is metastable relies on the false assumption that the Standard Model is correct all the way up to the Planck scale. We already have evidence to the contrary, e.g. dark matter.

    This metastability thing is a long-standing puzzle, only recently picked up and publicized by the popular press, such as in the SciAm article. The interesting thing about it is to understand why the Higgs mass lies where it does. Not that the model is actually correct, but whether there is some other significance to the fact that the masses of the Higgs and top quark fall on this line.
     
  8. Apr 2, 2013 #7
    Not knowing is totally different from knowing not.
    IF the vacuum tunnelled to a lower energy state, could this result in the disappearance of rest mass?
     
  9. Apr 3, 2013 #8

    Bill_K

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    Well, since you want it so bad, I will just say "yes", even though the real answer involves unknown Planck-scale physics.

    For those seriously interested in the metastability question, here are two references for comparison, both from the recent work of Joe Lykken: The first is a popularized account of an interview, playing up the doom and gloom aspect. The second consists of slides from a lecture presented a few weeks ago at Moriond. Note particularly slides 18-21. Quotes from the latter:

     
  10. Apr 3, 2013 #9
    Would the Higgs potential change shape if the vacuum changed to a lower energy state?
    It's apparently because of the unusual shape of the Higgs potential, where the highest-symmetry spot is not the lowest energy, that the Higgs boson can generate mass.
    So if the vacuum were in a lower energy state, could the Higgs potential change so the highest-symmetry spot does have the lowest energy?
     
  11. Apr 3, 2013 #10

    Bill_K

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    No, the issue is in the other direction: what the Higgs potential does at large field values.

    I'm sure you've seen the usual picture of the Higgs potential, V(φ), a quartic curve, high in the center (φ = 0), a minimum at our present value φ = v, and rising indefinitely as φ gets larger. The point is that, even assuming that this simple picture is right (that V was quartic to begin with) the shape of V may be altered by quantum corrections.

    The instability idea is that V may not rise indefinitely after all. Somewhere at large φ it may start to fall again, possibly resulting in a second and deeper minimum. The masses induced by the Higgs for all the other particles are proportional to v, so in this second minimum they would also become larger.

    But again, to repeat myself, the scenario is a fairy tale, to be told with a wink and a nudge. There are so many assumptions and so many unknowns that go into it, one shouldn't take it seriously! It depends on the Standard Model being perfectly true. We all know it must break down at higher energies. If the stability argument has any value, it will be to help us understand how the model breaks down.
     
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