On July 2, 1967, American Vela satellites built to catch covert Soviet nuclear tests in space detected a blinding flash of gamma rays that matched no known weapon and came from deep space. That accidental discovery, quietly studied at Los Alamos and published in 1973, opened one of the longest-running mysteries in astronomy: where do gamma-ray bursts come from, and how can anything be that bright? This episode follows the decades of investigation, from the Compton Gamma Ray Observatory's BATSE instrument mapping thousands of bursts evenly across the sky to BeppoSAX catching the first fading afterglow in 1997 and pinning a burst to roughly six billion light years away.

We break down the physics that makes these events possible: collimation into ultra-relativistic jets that act like a laser pointer rather than a light bulb, inverse Compton sc ...