Amateur physicist here.

I recently found a huge directory of science and advanced math books. Problem is, I don't understand what any of the math titles mean. For example, here is a small selection of some of the words contained in the titles:

"Bäcklund transformations"
"Double affine Hecke algebras"
"Sobolev spaces"
"Subriemannian geometries"
"Abstract regular polytopes"
"K-theory"
"Topological geometrodynamics"
"Motivic cohomology"

Basically, I'm interested in constructing a time machine and want to learn only the relevant math. I don't want to waste my time or hard drive space on anything that isn't relevant. So what kinds of mathematics should I be self-studying?