EPISODE 4 - "INVENTING LIGO" - is Part 1 of our two-part history of LIGO -- the early years of gravitational wave science through to the creation and launch of LIGO's first phase, Initial LIGO in 2002. Our series is now an ebook, with the full text of every episode and 80 photographs! https://books2read.com/LIGO-ADiscoveryThatShooktheWorld