What advice would you give your twenty-year-old self, and what should they ignore?
Study broadly. Don’t specialize too early. Read history. Sooner or later, you’re going to have to specialize, but within the limits that you have to take obligatory courses to get a degree, keep your general education as broad as you can, because you never know what doors are going to open to new opportunities — ten, 15, 20 years down the road — because of changes in science and technology.