What are the states of matter? (physics)?
I was watching QI, and there was a question of how many states of matter there was, and obviously most would say 3 or 4, but they said 6, as they also counted Bose-Einstein-condensate and Fermionic condensate. This made me curious, so I did a bit of read up.
As far as I can tell, they are both low-temperature superfluids. But there are several low-temperature superfluids which have much the same characteristica, so why are some counted and some not?
So what actually defines a state of matter?
If we base it on the differences in molecular interrelationships, which is very easy to see for the first 3 states of matter, then why is glass or liquid crystal not separate states? To me, it seems they indeed form very different 'patterns' or interrelationships between their molecules than the other states.
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There is a long list which are not considered states of matter (supersolids, degenerate matter, string-net liquid, super glass, dark matter (though, I suppose we don't know enough about that one to categorize it as anything), other kinds of plasma (or does the current state of plasma include both this and the regular ionized gas-kind?), other kinds of low-temperature states, many kinds of grid-like states, which are not counted...
So making a short, simple list of states of matter seems flawed, so maybe there ought to be just the 3 classical states of matter, defined as the common states, natrually occuring on earth, and then keep the rest which are more theoretical, cosmology-relevant, or lab-created states on another list, so to say? Or what? Are there any out there who are very knowledgeable on the subject, and can tell me a bit about what physicist think should be included on the list of states? I find it very interesting :D
I know plasma is quite common in the universe, that's why I specified it to the earth.
And I think you are right, that any definition we see, is based on what should make the list or not.