Measuring a change in length smaller than one ten-thousandth of a proton across four kilometers sounds like a cruel thought experiment, yet that is exactly what the Laser Interferometer Gravitational-Wave Observatory does. This episode covers the century-long road from Einstein's 1916 prediction, and his doubts that the waves could ever be detected, through the work of Soviet theorists, Joseph Weber's resonant mass antennas, and the laser interferometry prototypes of Rainer Weiss and Kip Thorne. It also digs into the messy 1980s and early 1990s, when a forced MIT-Caltech partnership, frozen NSF funding, and organizational chaos nearly killed the project until Barry Barish took over in 1994.

The hosts explain Barish's evolutionary pitch, an initial LIGO that would likely detect nothing followed by an Advanced LIGO upgrade, which secured roug ...