# What determines a state of matter?

Earlier I studied about the three states of matter-gaseous,liquid ans solid. Then, I came to know about Plasma and Bose-Einstein Condensate. Now, scientists are trying to explain superconductivity as a state of matter. But, I would like to know on what factors does scientists rely to decide whether a particular state is a state of matter?

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In general a state of matter is distinguished from other states by a phase transition, which can be accompanied by a changing symmetry. Superconductivity is such a state and since 50 years described in such a way, so not a new explanation. Maybe you can be a bit more specific, at the moment the answer spans several chapters in many statistical physics/condensed matter textbooks. – Alexander Nov 22 '13 at 12:00
@Alexander Can you please tell about how to make this question more specific? I think this question is getting not much attention as it is a broad one as you said. – Rajath Krishna R Nov 22 '13 at 13:16
@Alexander Alexander gave the generic answer for your generic question. A phase of matter is separated from an other one by a phase transition. So, a plasma is not a phase of matter, whereas gas (no interaction), liquid (interaction), solid (interaction + space ordering / lattice) are. Quantum condensates are a bit more tricky to classify, and this question is to a large extend not resolved. Maybe you could try to check on Wikipedia the pages about Bose-Einstein and superconducting condensates, and come back with more explicit questions about them. Have fun learning more about that. – FraSchelle Nov 25 '13 at 13:49
(to be continued) Also, you could try to obtain more information on the internet between first and second order phase transition. Classical phases of matter are separated from each other by a first order phase transition. But classical phases are just gas - liquid - solid, so it is not a big issue to learn about that. On the other hand, the quantum condensates are usually separated to the non-condensed-phase by a second order phase transition (say, because once more time reality is much more complicated). There is (still) no generic mechanism characterising quantum condensate. – FraSchelle Nov 25 '13 at 13:52