Chin-Ping Hu

In 1936, two physicists, Werner Heisenberg and Hans Euler, poring over the equations of quantum electrodynamics, found something strange. In a sufficiently strong magnetic field, vacuum should cease to be empty.

The Crab Nebula flickers with X-ray flashes thirty times per second. That's the beat of a pulsar — a dead star that spins and sends us pulses like a lighthouse. Japan's NinjaSat, a satellite the size of a shoebox, caught these flashes to figure out where it was.