In 1979 an invisible wall of gamma radiation swept across the solar system, hitting the Soviet Venera probes, then NASA's Helios-2, then satellites around Venus and Earth. Triangulating the timing pointed to a stellar remnant in the Large Magellanic Cloud, outside our galaxy. This episode explains the source: a magnetar, a rare class of neutron star proposed by Robert Duncan and Christopher Thompson in 1992. The hosts describe how a star of 10 to 25 solar masses collapses into a 20 kilometer sphere so dense that a tablespoon would weigh over 100 million tons, and how conservation of magnetic flux plus an internal dynamo can amplify the field to around 100 billion tesla.

From there the conversation gets stranger. At a thousand kilometers a magnetar's field would stretch the atoms in your body into narrow cylinders, breaking every chemical bo ...