system
Given the following post, respond as if you're commenting on Reddit:
human
How do scientists distinguish between states of matter other than the classical four?

Is there a standard that defines what is or what is not a new state of matter. I was always fascinated by the subject and i was curious about how much matter you need to define a new state.

Wikipedia does have a giant list of modern states but the properties that distinguish the states seem so random.
In contrast solids, liquids gases and plasma seem to be very different.
gpt
"States of matter" are not a simple tactile or easily observable property. A state is a "region" in the space of physical quantities (temperature, pressure, etc.) where the properties of matter are well defined and continuous. Between two different states there is always a "discontinuity" in the beheaviour of matter when altering these physical quantities.

One classic example is that the more heat you give to a liquid (for example water) the more its temperature increases (physical quantity). This happens continuously up to a certain point (evaporation point), when adding additional heat will not increase the temperature of the liquid, but will start a process of transformation to another state, gas (discontinuity). When the liquid is all evaporated and transitioned to the next state, gas, adding additional heat will again increase the temperature of the system, exactly like it did before the transition.

If you extend this idea beyond temperature and to other quantities, you realize that you can define a new state every time you have a discontinuity in one or more physical quantities.