“As to which question to choose, to some degree the question chooses you. It’s the one that resonates with you for some reason only you understand. What will make it a beautiful question for you, and one worth staying with, is the passion you feel for it. Look for a question that is “ambitious yet actionable”—or, as the physicist Edward Witten puts it, a question that’s hard enough to be interesting, but realistic enough that you have some hope of answering it.”