4 ms·

I'm not convinced that comparing two different states of matter is a useful comparison. The universe doesn't necessarily work differently, we're just observing

by eyko 5y ago

I'm not convinced that comparing two different states of matter is a useful comparison. The universe doesn't necessarily work differently, we're just observing different phenomena, aren't we? The behaviour of an atom or subatomic particles in isolation is not necessarily the behaviour of the same particles when part of a much larger system. Could one could also argue that quantum indeterminacy makes it difficult make predictions the more interactions you add to a system? That is, interactions at the atomic and subatomic levels are manageable enough to observe, but as we add actors, the interactions grow exponentially, and each actor's state is influenced not just by itself but by other actors in the system, ad infinitum.

dotancohen 5y ago
> 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).
- eyko 5y ago
  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!
- Filligree 5y ago
  > 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.
  - dotancohen 5y ago
    > "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.
    - Filligree 5y ago
      This, more or less: https://en.wikipedia.org/wiki/False_vacuum_decay#Inflation 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.

by eyko 5y ago

dotancohen 5y ago

> 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).

eyko 5y ago
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!
Filligree 5y ago
> 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.
- dotancohen 5y ago
  > "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.
  - Filligree 5y ago
    This, more or less: https://en.wikipedia.org/wiki/False_vacuum_decay#Inflation 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.