Rainer Weiss and How LIGO Came to Be

In 1972 Rainer (Rai) Weiss distributed to colleagues a technical paper in which he described a detector for gravitational waves (GWs), which has come to be called a GW interferometer.   Rai’s paper became the intellectual foundation for LIGO because in it he analyzed the major noise sources that such an instrument would face, he proposed ways to mitigate each noise source, he estimated the sensitivity of the resulting GW interferometer if all the noise sources were so mitigated, and he concluded that, with arms one kilometer long, it might be sufficiently sensitive to detect gravitational waves from the Crab Pulsar (a rapidly spinning neutron star).   In this talk, I will describe Rai’s seminal paper and what led up to it.  And I will then focus on his central roles in the follow-on GW interferometer R&D, the creation of the MIT/Caltech LIGO collaboration, the planning and funding and engineering of LIGO (under the directorship of Robbie Vogt), and the expansion of the collaboration to hundreds of physicists and engineers in more than a dozen countries (under the directorship of Barry Barish), with Rai the first spokesman for this LIGO Scientific Collaboration.   And I will describe Rai’s enormous impact on LIGO, and his  profound impact on me personally  -- to the point that I came to call him my ‘transcontinental soul-mate.”