Ask a Physicist: The Blood of a Starship

Recently, a reader by the name of Robert wrote in with a fun question that has an even more fun answer: I'm trying to find a material that acts like a liquid under high pressures, but also acts as a solid at low pressures. I'm trying to design a kind of fictional armor for my spacecraft, I want something that will fill holes produced by impact and weapons fire. The only problem is: I don't know if something like that can exist. Robert,Thanks for writing in! What you're describing is a non-Newton...