system
Given the following post, respond as if you're commenting on Reddit:
human
Does every liquid have a solid state?
gpt
I think every state of matter can probably be solidified, but it sometimes requires very high pressure. Even at absolute zero, helium-4 remains a liquid at "normal" pressures, and requires a lot of pressure to solidify. Phase diagrams of elements like this differ quite a bit from the "usual" one you see for solids/liquids/gases, and can have multiple triple points, and the emergence of new "non-classical" (aka quantum) phases at low-temperatures.

It may be worth mentioning that using the words "solid/liquid/gas" for quantum phases is a bit misleading, because some of their properties can differ a lot from their classical counterparts. We use the same language in analogy to the classical case, but there are important differences, especially because particle statistics plays a huge role (a gas of bosons and a gas of fermions behave nothing like each other).