Eli5: What are the other states of matter aside from solid, liquid and gas and why are they not being taught in schools?
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Commonly in the world around us, most elements only exist as a solid, liquid, and gas. The only other state of matter is plasma which is essentially super-heated gas. Plasma exists in astronomical features like stars, but that is the only other state of matter.
There are things like plasma and Bose-Einstein condensates, etc. They are harder to explain because they do require a fairly good understanding of the underlying physics which is probably a good bit above the level of most high schools.
Also, easier to explain the basics of phase diagrams with the 3 most common and easily experimented on states of matter. Plasma physics and the physics of low temperature are not easily observed without rather expensive lab equipment (and the people who can run the experiments tend to be expensive to hire too)
To answer the second part of your question as folks answered the first part.
It would be unnecessary. One could go through their entire life without having found a useful purpose for the knowledge surrounding the many states of matter beyond the main 4(because plasma is more common than you may think). We simply don’t encounter them frequently enough for them to be pertinent to education outside the few fields where they actually play a significant enough role.
First of all, you should have been taught about plasma.
If you didn’t learn about plasma, get a refund on your diploma.
Beyond that, though….
There are a few dozen, at least.
It’s hard to give an exact number or an exact list because “state of matter” is not precisely defined, and it’s sometimes hard to give a hard line of demarcation between them.
Some of them are really exotic, and don’t really come up except under very strange (or even theoretical, never seen before) situations.
You can’t expect to learn about those in school because you would first have to learn about the situations under which they (theoretically) arise, which could require several years of advanced physics.
Some of them are really mundane, like “glass”.
The thing about glass is that, while glass is all around us and we can understand it fairly well, the precise properties that cause us to (often) consider it distinct from other states of matter are not terribly relevant to what else you’re learning about.
When you learn about states of matter in school, you’re usually learning really basic and easily observed differences between them (liquids fit the shape of their container, and solids don’t…kind of) and glass doesn’t have in-your-face characteristics like that.
You *could* teach glass in a high school science class (and I’m sure there are some science teachers who do or have), but you’d have to get into crystalline structures and I think you’d have to be teaching to a class of students who are extraordinarily interested in materials.
As the main questions have already been answered a historical comment: the four “elements” as described by ancient cultures correspond very well to the four common states of matter:
– Earth: solid
– Water: liquid
– Air: gas
– Fire: plasma
Hence not at least those four being taught in schools sounds almost silly.
It went by the way a bit further, e.g. in [Neo-Platonism](https://en.wikipedia.org/wiki/Classical_element#Neo-Platonism). Some schools of thought also added a fifth element, sometimes aether, sometimes space or void.
The states of matter model is now considered obsolete in doctorate level physics. That being said, it makes no sense to consider plasma a different form of matter because there’s no cut off, no point by which we can clearly distinguish gasses and plasma. Plasma is just more ionized gas and the change is completely linear, unlike the changes between solid, liquid and gas
There isn’t really universal agreement on what counts as a state of matter, but most people would agree that there are quite a lot of them, some of which are fairly obscure and difficult to understand. Kids really don’t need to know about neutron degenerate matter, for example.
The thing that is usually used to define states of matter is a phase transition. If you gradudally change one property of a substance (e.g. its temperature) and there is a certain point at which another property undergoes a sharp change (e.g. water at -0.1°C is much more rigid than water at 0.1°C), that’s called a phase transition. This definition works pretty well for most states of matter, but it leads you to some weird conclusions. For example, when molten glass cools, there doesn’t appear to be a phase transition, but surely molten glass and solid glass are two different states of matter. Similarly, at really high pressures the phase transition between liquid and gaseous water disappears. So a “state of matter” is ultimately one of those “I know it when I see it” things.
Sorry for not providing additional description of what exactly I was asking for. I didn’t meant about the 4 commonly known states of matter. I was actually asking about the other states like bose-einstein condensate, photonic matter, quantum hall state, etc.
Really appreciate the replies
There are three classical states of mater, solid, liquid and gass, solids melts into liquids, and vaporize to gasses, before condensing to liquids and freezing to solids, these are the only matters you gonna interact with in day to day, you also got a 4th state, that falls under the classical matter, plasma, plasma is electrically charged gas, its generated in fluorescent lights, lightning, and neon lights, to create plasma you need to ionize it, and there are two methods for that, and both of them are essentially just add more energy, but the ones you would be thinking of is superconducter, superfluid and supersolid, neither are states you will ever experience, outside of super conductors, which just have zero electrical resistance.
As for states i did not mention like bose-einstein condenstate, they are mostly just hypothetical, and just exists in theory.
Plasma is commonly called the fourth state of matter. This happens when it is very hot and very high pressure, like in the middle of a star. The atom kicks out some of its electrons and you get a jumble of charged particles.
Other forms are considered more “exotic” and only occur in special conditions, like very close to “absolute zero” (-273.15°C). Bose-Einstein Condensate is one of these. They’re pretty weird and since we don’t encounter them in day to day applications, they’re not taught in schools as people don’t *need* to know about them unless they’re doing science degrees.
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