Rainer Weiss, Gravitational-Wave Pioneer, Passes Away at 92

Renowned physicist Rainer Weiss, who played a pivotal role in the discovery of gravitational waves, died on August 25, 2023, at the age of 92. Weiss was awarded the Nobel Prize for Physics in 2017 for his groundbreaking work that led to the detection of these elusive cosmic phenomena. His visionary approach involved measuring minute changes in distance—down to 10^-18 m—using a long interferometer, a concept that ultimately gave birth to the Laser Interferometer Gravitational-Wave Observatory (LIGO).

Born on September 29, 1932, in Berlin, Germany, Weiss faced early challenges as the son of a Jewish father and a fervent communist. His family fled to Czechoslovakia and then to the United States in 1939, escaping the rise of the Nazi regime. Raised in New York, Weiss received his education at Columbia Grammar School through the support of a refugee relief organization.

In 1950, Weiss began his studies in electrical engineering at the Massachusetts Institute of Technology (MIT) but later transitioned to physics, earning his PhD in 1962 under the mentorship of Jerrold Zacharias. He initially worked at Tufts University and later joined Princeton University as a research associate to physicist Robert Dicke. By 1964, he returned to MIT, where he began formulating his idea for a large-scale interferometer aimed at detecting gravitational waves.

In collaboration with Kip Thorne at the California Institute of Technology (Caltech), Weiss prepared a feasibility study for constructing a kilometre-scale laser interferometer. This project gained traction when the National Science Foundation funded the development of LIGO in 1979. Construction of two detectors—one in Hanford, Washington, and another in Livingston, Louisiana—commenced in 1990, with both facilities officially opening in 2002.

For years, the detectors remained silent, failing to detect gravitational waves until a significant upgrade in 2011 enhanced their sensitivity tenfold. Success came on September 14, 2015, when LIGO recorded gravitational waves generated by two merging black holes located approximately 1.3 billion light-years from Earth. This monumental discovery was publicly announced in February 2016, marking a new era in astrophysics.

Weiss received the Nobel Prize for Physics in 2017, sharing the accolade with Thorne and fellow physicist Barry Barish, who served as LIGO’s project director. The trio was recognized “for decisive contributions to the LIGO detector and the observation of gravitational waves.”

Apart from his achievements in gravitational wave detection, Weiss contributed to the development of atomic clocks and led initiatives to measure the cosmic microwave background spectrum through weather balloons. He co-founded NASA’s Cosmic Background Explorer project, which provided vital data supporting the Big Bang theory of the universe’s expansion.

In recognition of his profound impact on the field, Weiss received numerous accolades, including the Gruber Prize in Cosmology in 2006, the Einstein Prize from the American Physical Society in 2007, and both the Shaw Prize and the Kavli Prize in Astrophysics in 2016.

Nergis Mavalvala, MIT’s Dean of Science and a former student of Weiss, remarked on his influence: “Every gravitational-wave event that is observed will be a reminder of his legacy.” She expressed her sorrow at his passing, stating, “Weiss leaves an indelible mark on science and a gaping hole in our lives. I am heartbroken, but also so grateful for having him in my life, and for the incredible gifts he has given us—of passion for science and discovery, but most of all to always put people first.”

Weiss’s contributions to science have left an enduring legacy, shaping the way we understand the universe and inspiring future generations of scientists.