At one point maybe 20 years ago, I did an informal study of quantum physics--something on the order of "Quantum Physics for Dummies" (which is an actual book). Every time I would delve into the subject I would get my mind blown. Concepts such as "quantum entanglement", where atomic information ends up instantaneously (apparently, teleported) spread among several particles at once; or Einstein's "spooky action at a distance" when it's possible for a single particle to be in two places at once.

This is deeply subversive stuff, and I love it.