Spyridon Michalakis in Scientific American:
It all began with a simple question.
My adviser at Los Alamos, Matthew Hastings, a rising star and one of the sharpest minds in physics, was sitting across from me at a sushi restaurant when he popped the fateful question: “For your postdoc here at the lab, do you want to start with a warm-up, or do you want to work on something interesting?” Without asking for further clarification, I answered, “I want to work on something interesting.” He seemed pleased with my answer. Later that day he sent me a link to a list of 13 unsolved problems in physics maintained by Michael Aizenman, a professor at Princeton University and a towering figure in mathematical physics. I was to work on the second problem on that list, a question posed by mathematical physicists Joseph Avron and Ruedi Seiler: “Why is the Hall conductance quantized?”
More here.