If you compress hydrogen to that pressure and keep it compressed in let’s say a really strong shell, then it will have superconductivity even at room temperature.

That sentence is not great because copper is not a superconductor. https://www.engineeringenotes.com/metallurgy/metal-conductiv...

Quick question, can you really have room temperature at that pressure? I thought extreme pressures would always result in extreme temperatures.

> I thought extreme pressures would always result in extreme temperatures.

At least classically, it's the process of compressing that yields the extreme temperatures, not the state of having been compressed. If you maintain the pressure, the hot compressed material will transfer thermal energy to its surroundings until it has cooled back down to room temperature, and it does not require further work to be done on the compressed material to keep it compressed.

If you keep it compressed, it will eventually cool down, but stay compressed.

If it's a solid in that state, will it remain a solid if you remove the container?

I think it’s still an open question if it is metastable (like diamond>graphite), but it definitely wouldn’t be stable.

https://physics.stackexchange.com/questions/308290/are-there...

Depends. If you remove the container quickly, then it explodes. Dong it slowly, some of the material evaporates and thus cools the rest, so that you can end up with piece of ultracold solid. But it will most likely not have same properties as the original material.

no

Ow... That's disappointing.