A fast radio burst can release as much energy in a millisecond as the Sun emits in three days, yet by the time it reaches Earth the signal is a thousand times weaker than a cell phone broadcasting from the Moon. This episode explores how astronomers study a phenomenon that vanishes almost as soon as it appears, starting with the 2007 Lorimer Burst, a 30 Jansky spike lasting under five milliseconds that Duncan Lorimer and David Narkevic found in archival 2001 data from Australia’s Parkes Observatory.

The hosts explain how dispersion measure proved the signal came from billions of light years away and turned every FRB into a cosmic measuring tape, how the repeating FRB 121102 and the 16.35-day cycle of FRB 180916 shattered the cataclysm theory, and why Faraday rotation points to extreme magnetic environments rather than alien light sails. They cover the light-travel argument that limits the source to a few hundred kilometers, the April 2020 CHIME detection that traced a burst to the Milky Way magnetar SGR 1935+2154, the synchrotron maser mechanism, and the January 2025 discovery of an FRB in an 11-billion-year-old dead galaxy that complicates the young-magnetar consensus.

• How low-frequency radio waves lag behind high-frequency ones in interstellar plasma, revealing the distance a burst has traveled
• Why a signal repeating on a strict schedule raised the question of technosignatures, and why the energy requirements make that improbable
• How a snapping magnetar field drives relativistic shocks that force electrons to emit coherent radio pulses in unison
• What a 2024 Italian INAF study proposed about binary systems and plasma bubbles as sources of persistent repeaters
• Why cosmic strings, axion miniclusters, and evaporating primordial black holes remain on the table for outlier bursts