Is there a limit to how strong a material we can create? Does yield strength have an upper bound, and how high is that upper bound above materials created today? What about hardness? Is Diamond the limit? Could we ever make a machine that could survive the pressures and temperature found in the earth's core? I'm also wondering whether it's possible to create a stable material denser than Osmium? Density is distinct from strength, I know, but it's also something I've been wondering.