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Professor Emeritus Rainer Weiss, influential physicist who forged new paths to understanding the universe, dies at 92

The longtime MIT professor shared a Nobel Prize for his role in developing the LIGO observatory and detecting gravitational waves.
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Caption: MIT Professor Emeritus Rainer Weiss ’55, PhD ’62, photographed in 2016
Credits: Credit: Bryce Vickmark
Rai Weiss and five colleagues sit around a table with instrumentation on top, in a lab. They all wear blue slippers over their shoes.
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Caption: The MIT LIGO team in January 2016, before scientists announce the first direct detection of gravitational waves: David Shoemaker, Rainer Weiss, Matthew Evans, Erotokritos Katsavounidis, Nergis Mavalvala, and Peter Fritschel.
Credits: Credit: Bryce Vickmark
A young Rainer Weiss working at a lab bench
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Caption: Rainer Weiss, seated in his lab in MIT’s former Building 20 in the late 1970s, works on a cryogenically cooled detector for cosmic microwave background radiation.
Credits: Credit: Peter Kramer, courtesy of MIT LIGO Laboratory
Grayscale headshot of a young Rainer Weiss
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Caption: Early file photo of MIT physicist Rainer Weiss, who had a seven-decade affiliation with the Institute, starting as an undergraduate student in 1950 and concluding as a professor emeritus.
Credits: Image courtesy of the MIT Museum

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Rainer Weiss headshot
Caption:
MIT Professor Emeritus Rainer Weiss ’55, PhD ’62, photographed in 2016
Credits:
Credit: Bryce Vickmark
Rai Weiss and five colleagues sit around a table with instrumentation on top, in a lab. They all wear blue slippers over their shoes.
Caption:
The MIT LIGO team in January 2016, before scientists announce the first direct detection of gravitational waves: David Shoemaker, Rainer Weiss, Matthew Evans, Erotokritos Katsavounidis, Nergis Mavalvala, and Peter Fritschel.
Credits:
Credit: Bryce Vickmark
A young Rainer Weiss working at a lab bench
Caption:
Rainer Weiss, seated in his lab in MIT’s former Building 20 in the late 1970s, works on a cryogenically cooled detector for cosmic microwave background radiation.
Credits:
Credit: Peter Kramer, courtesy of MIT LIGO Laboratory
Grayscale headshot of a young Rainer Weiss
Caption:
Early file photo of MIT physicist Rainer Weiss, who had a seven-decade affiliation with the Institute, starting as an undergraduate student in 1950 and concluding as a professor emeritus.
Credits:
Image courtesy of the MIT Museum

Audio

MIT Professor Emeritus Rainer Weiss ’55, PhD ’62, a renowned experimental physicist and Nobel laureate whose groundbreaking work confirmed a longstanding prediction about the nature of the universe, passed away on Aug. 25. He was 92.

Weiss conceived of the Laser Interferometer Gravitational-Wave Observatory (LIGO) for detecting ripples in space-time known as gravitational waves, and was later a leader of the team that built LIGO and achieved the first-ever detection of gravitational waves. He shared the Nobel Prize in Physics for this work in 2017. Together with international collaborators, he and his colleagues at LIGO would go on to detect many more of these cosmic reverberations, opening up a new way for scientists to view the universe.

During his remarkable career, Weiss also developed a more precise atomic clock and figured out how to measure the spectrum of the cosmic microwave background via a weather balloon. He later co-founded and advanced the NASA Cosmic Background Explorer project, whose measurements helped support the Big Bang theory describing the expansion of the universe.

“Rai leaves an indelible mark on science and a gaping hole in our lives,” says Nergis Mavalvala PhD ’97, dean of the MIT School of Science and the Curtis and Kathleen Marble Professor of Astrophysics. As a doctoral student with Weiss in the 1990s, Mavalvala worked with him to build an early prototype of a gravitational-wave detector as part of her PhD thesis. “He will be so missed but has also gifted us a singular legacy. Every gravitational wave event we observe will remind us of him, and we will smile. I am indeed 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.” she says.

A member of the MIT physics faculty since 1964, Weiss was known as a committed mentor and teacher, as well as a dedicated researcher. 

“Rai’s ingenuity and insight as an experimentalist and a physicist were legendary,” says Deepto Chakrabarty, the William A. M. Burden Professor in Astrophysics and head of the Department of Physics. “His no-nonsense style and gruff manner belied a very close, supportive and collaborative relationship with his students, postdocs, and other mentees. Rai was a thoroughly MIT product.”

“Rai held a singular position in science: He was the creator of two fields — measurements of the cosmic microwave background and of gravitational waves. His students have gone on to lead both fields and carried Rai’s rigor and decency to both. He not only created a huge part of important science, he also populated them with people of the highest caliber and integrity,” says Peter Fisher, the Thomas A. Frank Professor of Physics and former head of the physics department.

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Enabling a new era in astrophysics

LIGO is a system of two identical detectors located 1,865 miles apart. By sending finely tuned lasers back and forth through the detectors, scientists can detect perturbations caused by gravitational waves, whose existence was proposed by Albert Einstein. These discoveries illuminate ancient collisions and other events in the early universe, and have confirmed Einstein’s theory of general relativity. Today, the LIGO Scientific Collaboration involves hundreds of scientists at MIT, Caltech, and other universities, and with the Virgo and KAGRA observatories in Italy and Japan makes up the global LVK Collaboration — but five decades ago, the instrument concept was an MIT class exercise conceived by Weiss.

As he told MIT News in 2017, in generating the initial idea, Weiss wondered: “What’s the simplest thing I can think of to show these students that you could detect the influence of a gravitational wave?”

To realize the audacious design, Weiss teamed up in 1976 with physicist Kip Thorne, who, based in part on conversations with Weiss, soon seeded the creation of a gravitational wave experiment group at Caltech. The two formed a collaboration between MIT and Caltech, and in 1979, the late Scottish physicist Ronald Drever, then of the University of Glasgow, joined the effort at Caltech. The three scientists — who became the co-founders of LIGO — worked to refine the dimensions and scientific requirements for an instrument sensitive enough to detect a gravitational wave. Barry Barish later joined the team at Caltech, helping to secure funding and bring the detectors to completion.

After receiving support from the National Science Foundation, LIGO broke ground in the mid-1990s, constructing interferometric detectors in Hanford, Washington, and in Livingston, Louisiana. 

Years later, when he shared the Nobel Prize with Thorne and Barish for his work on LIGO, Weiss noted that hundreds of colleagues had helped to push forward the search for gravitational waves.

“The discovery has been the work of a large number of people, many of whom played crucial roles,” Weiss said at an MIT press conference. “I view receiving this [award] as sort of a symbol of the various other people who have worked on this.”

He continued: “This prize and others that are given to scientists is an affirmation by our society of [the importance of] gaining information about the world around us from reasoned understanding of evidence.”

“While I have always been amazed and guided by Rai’s ingenuity, integrity, and humility, I was most impressed by his breadth of vision and ability to move between worlds,” says Matthew Evans, the MathWorks Professor of Physics. “He could seamlessly shift from the smallest technical detail of an instrument to the global vision for a future observatory. In the last few years, as the idea for a next-generation gravitational-wave observatory grew, Rai would often be at my door, sharing ideas for how to move the project forward on all levels. These discussions ranged from quantum mechanics to global politics, and Rai’s insights and efforts have set the stage for the future.”

A lifelong fascination with hard problems

Weiss was born in 1932 in Berlin. The young family fled Nazi Germany to Prague and then emigrated to New York City, where Weiss grew up with a love for classical music and electronics, earning money by fixing radios.

He enrolled at MIT, then dropped out of school in his junior year, only to return shortly after, taking a job as a technician in the former Building 20. There, Weiss met physicist Jerrold Zacharias, who encouraged him in finishing his undergraduate degree in 1955 and his PhD in 1962.

Weiss spent some time at Princeton University as a postdoc in the legendary group led by Robert Dicke, where he developed experiments to test gravity. He returned to MIT as an assistant professor in 1964, starting a new research group in the Research Laboratory of Electronics dedicated to research in cosmology and gravitation.

With the money he received from the Nobel Prize, Weiss established the Barish-Weiss Fellowship to support student research in the MIT Department of Physics.

Weiss received numerous awards and honors in addition to the Nobel Prize, including the Medaille de l’ADION, the 2006 Gruber Prize in Cosmology, and the 2007 Einstein Prize of the American Physical Society. He was a fellow of the American Association for the Advancement of Science, the American Academy of Arts and Sciences, and the American Physical Society, as well as a member of the National Academy of Sciences. In 2016, Weiss received a Special Breakthrough Prize in Fundamental Physics, the Gruber Prize in Cosmology, the Shaw Prize in Astronomy, and the Kavli Prize in Astrophysics, all shared with Drever and Thorne. He also shared the Princess of Asturias Award for Technical and Scientific Research with Thorne, Barry Barish of Caltech, and the LIGO Scientific Collaboration.

Weiss is survived by his wife, Rebecca; his daughter, Sarah, and her husband, Tony; his son, Benjamin, and his wife, Carla; and a grandson, Sam, and his wife, Constance. Details about a memorial are forthcoming.

This article may be updated.

Press Mentions

Nature

Writing for Nature, Bruce Allen pays tribute to Prof. Emeritus Rainer Weiss, a pioneering physicist who “spearheaded the construction of the LIGO observatory to detect Einstein’s predicted ripples in space-time [and] leaves a legacy of persistence and mentorship.” Allen recalls how, decades earlier, Weiss rejoiced in a moment of discovery with him. “This is why we do science,” Weiss said. “Not for prizes or awards — that’s all nonsense. It’s for the satisfaction when something you’ve struggled with finally works.” Weiss, Allen emphasizes, was “a scientist driven by curiosity, persistence and the joy of understanding how the Universe works.”

The Wall Street Journal

Wall Street Journal reporter Jon Mooallem memorializes the life and work of Prof. Emeritus Rainer Weiss, from his time hacking surplus military electronics into sophisticated hi-fi receivers as a teenager to dreaming up the concept for the Laser Interferometer Gravitational-Wave Observatory (LIGO). Mooallem notes that Weiss and his LIGO colleagues’ breakthrough in achieving the first-ever detection of gravitational waves “has provided a new way of looking at the universe, of observing, through the charting of gravity waves emitted by moving objects, what was previously unobservable or unknown—a milestone that is frequently compared with Galileo’s invention of the telescope.”

The Boston Globe

Prof. Rainer Weiss, a Nobel Prize-winning physicist whose research helped “unlock the secrets of the universe,” has died at 92, reports Bryan Marquard for The Boston Globe. “He really is, by a large margin, the most influential person this field has seen. And will see,” said Caltech Prof. Emeritus Kip Thorne. Nergis Mavalvala, dean of the MIT School of Science who conducted her doctoral research with Weiss, shared that Weiss “worked on three different things, and every one of them has changed the way we understand physics and the universe.”

Tri-City Herald

Tri-City Herald reporter Annette Cary memorializes the life and legacy of MIT Prof. Emeritus Rainer Weiss, a “renowned experimental physicist and Nobel laureate,” who was “key to [the] world’s first gravitational wave discovery.” At the opening ceremony in June 2022 for the LIGO Exploration Center in Hanford, Washington, Weiss relayed how life is more interesting if you have a deeper understanding of the world around you and “how science does its tricks.”

Space.com

Prof. Emeritus Rainer Weiss, a “renowned experimental physicist” who was “integral in confirming the existence of tiny ripples in spacetime called ‘gravitational waves,’” has died, reports Robert Lea for Space.com. “Remarkably, in confirming the existence of gravitational waves, Weiss both proved Einstein right and wrong at the same time,” writes Lea. “Einstein had been convinced that these ripples in spacetime were so faint that no apparatus on Earth could ever be sensitive enough to detect them, showing just how revolutionary LIGO was.”

Physics World

Physics World reporter Michael Banks chronicles the life and work of MIT Prof. Emeritus and gravitational wave pioneer Rainer Weiss. “Weiss came up with the idea of detecting gravitational waves by measuring changes in distance as tiny as 10–18 m via an interferometer several kilometers long,” writes Banks. “His proposal eventually led to the formation of the twin Laser Interferometer Gravitational-Wave Observatory (LIGO), which first detected such waves in 2015.” 

New York Times

Professor Emeritus Rainer Weiss, a Nobel Prize-winning physicist who was honored for his work "developing a device that uses gravity to detect intergalactic events, like black holes colliding, and who helped confirm two central hypotheses about the universe,” has died at 92, reports Dylan Loeb McClain for The New York Times. In an earlier interview, Weiss reflected upon the wonder unlocked by LIGO: “With gravitational waves, you have a new way to look at [the] universe. You can see all that nature has in store. So now comes the question: What do you want to find out?”

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