Three of the most luminous supernovae on record — 2006gy, 2005gj, and 2005ap — pose problems for theorists. For example, 2006gy’s peak luminosity reached 50 billion Suns. That’s 10 times brighter than the average type Ia supernova and 100 times brighter than a representative type II. And 2005ap was 2 times brighter still. What’s a theorist to do? In our January issue, I noted that astronomers suspected some of these events might be so-called “pair...