New Challenge to the Big Bang?

Call it an unexpected bonus from the cold war. During top-secret monitoring of the dark side of the moon 25 years ago, U.S. scientists discovered what they feared might be clandestine Soviet nuclear tests in space. Spy satellites picked up massive bursts of gamma rays similar to those released during the explosion of atom bombs. But these bursters, as gamma-ray scientists began to call them, did not match any known pattern. They were brief, lasting from only a fraction of a second up to 100 seconds. Civilian experts were called in to study the data, and the Soviet-nuclear-test theory was eventually...