Scientists witness massive cosmic explosion

"There are a lot of unknowns, but their study tells us about the extreme conditions found in the universe."

The bursts appear to be associated with supernovas—the massive explosions caused by the deaths of some stars that can spawn black holes.

But a gamma-ray burst observed by NASA's Swift satellite on June 14, 2006, defies any currently known theories, because it reveals no evidence of an associated supernova.

"The fact that this one didn't [associate with a supernova] is making us rethink our whole idea of what can cause gamma-ray bursts," said Neil Gehrels of the NASA Goddard Spaceflight Center in Greenbelt, Maryland.