Steve Dodge on Nostr: I recognize that you are speaking to a general audience and my question arose out of ...

I recognize that you are speaking to a general audience and my question arose out of a mixture of curiosity of confusion. I can see why you might think that this usage of “state of matter” might confuse more than it clarifies in this context, but I still don’t understand your assertion that there are actually seven. Why seven, and what is the physical basis for this classification? It wasn’t clear to me from reading your piece.

FWIW, I’d also say it’s arguable whether liquid and gas are different states of matter. On one hand, they are separated by a line of first-order phase transitions, with water being the go-to example that makes the solid-liquid-gas classification seem natural. But on the other hand, you don’t need to pass through this line to change from one state to the other, and they have the same symmetry. Technically, my working definition of a “state of matter” is that it is separated from another state of matter by a phase transition. I can augment that by recognizing states with different topology.