Undergrad: Allen Hatcher's recommendation got me into Cornell (I learned Algebraic Topology through his book in high school, along with some email correspondences). But I majored in Engineering Physics, and did experimental research on gravity. Luckily, Ken Brown took me under his wing and provided weekly meetings to understand Group Cohomology.

Grad: I started my PhD in experimental atomic physics at Berkeley, but quit to do math. I am now a student of Michael Hutchings, wooo!