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B Universe within a universe

  1. Feb 5, 2017 #1

    Is it possible that there could be another big bang within our universe? What would this mean for our universe? Would it destroy us from the inside like the aliens from the Alien films?

    If quantum foam is like the canvas of reality and it gave way for the big ban then then why aren't we seeing big bangs all the time or is the big bang really just a one off/rare event?

    My body is made from quantum foam so what is there to stop my body from giving birth to another universe?
  2. jcsd
  3. Feb 22, 2018 #2
    Yes, it's very possible. It's called a phase transition in the inflaton field that permeates our universe. Essentially, the inflaton field is is a hypothetical scalar field responsible for driving inflation. If, through some quantum tunnelling phenomenon, a local region of the field drops in energy with respect to the surrounding field, it will expand like a little bubble universe would undergo inflation.
    If you want a more in depth explanation, read this.
  4. Feb 26, 2018 #3
    There are a lot of "ifs" in this.
    "If" there _is_ a field state with lower energy level than our current vacuum - which is not in any way a sure thing.
    "If" this state has a higher vacuum energy density than our vacuum (again, not assured by any means).
  5. Feb 26, 2018 #4
    Well, yes, there are a lot of “if’s” in my response since we’re discussing very theoretical things here. As I said, the inflaton field is a hypothetical field, meaning it exists in theory but we have yet to find evidence for it. And according to some of the math explaining the theory, there could possibly exist this so called phase transition. In this theoretical space, it’s very difficult to guarantee anything.
  6. Feb 26, 2018 #5


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    A nested doll universe is a concept that appears difficult to define mathematically. What kind of boundary conditions would render them sensibly distinct? It reminds me of some old black hole hypothese where event horizons served as a causal barrier between what amounts to parallel universes. It makes sense to require some kind of mathematically well defined causal boundary to erect a universe within a universe.
  7. Feb 26, 2018 #6


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    But, if our universe already went through the phase transition, then how could to go through it again?
    Unless, our universe is in some kind of "false vacuum" state.
  8. Feb 26, 2018 #7
    As far as I know there is no reason to believe that this is not the case. I can’t imagine any possible way to even theoretically determine if this is the case or not.
  9. Feb 26, 2018 #8
    It is possible but there has not so far been any reason or evidence which supports this idea.
  10. Feb 27, 2018 #9
    Why not? If/when our QFT math will be able to calculate quantum corrections to all orders, we will know the shape of the potential for all field values. Therefore, we will know how many local minimums it has, where they are, and what are their vacuum energies. I can imagine this.
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