Scientists may have to rethink their playbook for studying gamma-ray bursts, the most powerful known cosmic explosions, after a blast detected in July set a new record by firing energetic jets for days. Astronomers around the world detected the gamma-ray burst, or GRB, on July 2. Unlike typical GRBs, which NASA says occur daily and usually last only milliseconds to a few minutes, this one persisted far longer. “This is certainly an outburst…