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Comment by dotancohen | Hacker News Reader

  > I'm not convinced that comparing two different states of matter is a useful comparison.

Actually, it is probably a terrific comparison. What is a state change? It is a drastic change in the properties of a material once some threshold condition (usually temperature and/or pressure) is crossed. And in fact QM and GR describe the same system under different lenses - maybe not pressure or temperature but certainly different conditions.

Don't forget that the universe itself has undergone a phase transition, after (or during, depending on who's lecturing) the inflation period (very shortly after the big bang).

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> Don't forget that the universe itself has undergone a phase transition, after (or during, depending on who's lecturing) the inflation period (very shortly after the big bang).

I prefer calling it a vacuum collapse, 'cause that's what it was. "Phase transition" sounds too clinical.

Always wondered if there's any chance there may have been some form of life existing prior to reheating. It's not as though we have any way to find out, unfortunately.

  > "Phase transition" sounds too clinical.

I never liked the term either, but physicists use it because that is exactly what happened. I'm not going to argue with physicists.

What does "vacuum collapse" mean? No matter how I try to interpret it, I cannot come up with anything that resembles the cosmic inflation.

This, more or less: https://en.wikipedia.org/wiki/False_vacuum_decay#Inflation

The problem is we're not sure that's what caused reheating. There's been other suggestions, some of them quite exotic -- a collision with a neighbouring brane, for instance. Still, my bet's on false vacuum decay.

I was mainly thinking in the difference between an atom in laboratory conditions being observed in a very controlled way, vs an atom at the core of a protostar, for instance, but that's an interesting point, thanks!

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