Rainer Weiss
active c. 1932, Berlin, Germany
German-born American physicist, chief architect of LIGO — the gravitational-wave observatory that first detected colliding black holes.
Weiss worked at MIT, initially measuring background noise for the COBE satellite project. In 1972 he analyzed the km-scale laser interferometer as the only way to hear gravitational waves. With Kip Thorne and Barry Barish he turned the idea into LIGO — two giant L-shaped detectors in Louisiana and Washington that recorded the first signal, GW150914, in 2015.
Nobel-winning work
Weiss's 1972 analysis identified every noise source limiting interferometer sensitivity — quantum, thermal, seismic — and showed at what level gravitational waves could be measured. LIGO's 2015 signal from two ~30-solar-mass black holes merging 1.3 billion light-years away matched Einstein's general relativity, opening gravitational-wave 'multi-messenger' astronomy.
Workplaces: Massachusetts Institute of Technology
United States, Germany