Rainer Weiss

Rainer Weiss (/waɪs/ WYSSE, German: [vaɪs]; September 29, 1932 – August 25, 2025) was a German-American physicist, known for his contributions in gravitational physics and astrophysics. He was a professor of physics at the Massachusetts Institute of Technology and an adjunct professor at Louisiana State University. He is best known for inventing the laser interferometric technique which is the basic operation of LIGO. He was Chair of the COBE Science Working Group.

In 2017, Weiss was awarded the Nobel Prize in Physics, along with Kip Thorne and Barry Barish, "for decisive contributions to the LIGO detector and the observation of gravitational waves".

Weiss helped realize a number of challenging experimental tests of fundamental physics. He was a member of the Fermilab Holometer experiment, which uses a 40m laser interferometer to measure properties of space and time at quantum scale and provide Planck-precision tests of quantum holographic fluctuation.

Rainer Weiss was born in Berlin, Brandenburg, Prussia, Germany, on September 29, 1932, the son of Gertrude Loesner and Frederick A. Weiss. His father, a physician, neurologist, and psychoanalyst, was forced out of Germany by Nazis because he was Jewish and an active member of the Communist Party. His mother, an actress, was Christian. His aunt was the sociologist Hilda Weiss.^{[citation needed]} His younger sister is playwright Sybille Pearson.

The family fled first to Prague, but Germany's occupation of Czechoslovakia after the 1938 Munich Agreement caused them to flee again; the philanthropic Stix family of St. Louis helped them obtain visas to enter the United States. Weiss spent his youth in New York City, where he attended Columbia Grammar School.

He studied at MIT, dropping out at the beginning of his junior year with the excuse that he had abandoned his coursework to pursue a romantic relationship with a music student from Chicago. While this affair was a contributing factor, Weiss's concurrent vacillation between MIT's engineering and physics tracks may also have played a significant role. Jerrold Zacharias, then an influential physicist and MIT professor, intervened, and Weiss, after working as a technician in Zacharias's lab, eventually returned to receive his S.B. degree in 1955. He would complete his PhD in 1962, still with Zacharias as advisor/mentor.

Weiss taught at Tufts University from 1960 to 1962, was a postdoctoral scholar at Princeton University from 1962 to 1964, and then joined the faculty at MIT in 1964.

For Weiss's initial work at MIT, he started a group studying cosmology and gravitation. Needing to develop new technology, particularly in regards to the stabilization of equipment set to measure minute fluctuations, his lab included machine and electronics shop, with a hands-on expectation of his students for fabrication and design.