MIT Professor Emeritus Rainer Weiss ’55, PhD ’62, a distinguished experimental physicist and Nobel Prize winner whose pioneering contributions validated a long-held hypothesis regarding the universe’s essence, passed away on Aug. 25. He was 92.
Weiss devised the Laser Interferometer Gravitational-Wave Observatory (LIGO) to identify disturbances in space-time referred to as gravitational waves, and later took a leading role in the team that constructed LIGO, achieving the first-ever observation of gravitational waves. He was awarded the Nobel Prize in Physics for this endeavor in 2017. Alongside international partners, he and his team at LIGO would eventually detect numerous of these cosmic vibrations, creating a new avenue for scientists to examine the universe.
Throughout his extraordinary career, Weiss also engineered a more accurate atomic clock and discovered methods to assess the spectrum of the cosmic microwave background using a weather balloon. He later co-established and promoted the NASA Cosmic Background Explorer project, whose findings bolstered the Big Bang theory explaining the universe’s expansion.
“Rai leaves an indelible impression on science and an immense void in our lives,” states Nergis Mavalvala PhD ’97, dean of the MIT School of Science and the Curtis and Kathleen Marble Professor of Astrophysics. As a doctoral candidate studying under Weiss in the 1990s, Mavalvala collaborated with him to create an early model of a gravitational-wave detector for her doctoral thesis. “He will be profoundly missed but has also left us an exceptional legacy. Every gravitational wave event we witness will evoke memories of him, and we will smile. I am indeed grief-stricken, yet immensely thankful for having known him, and for the remarkable gifts he imparted — a passion for science and discovery, but above all, the importance of prioritizing people,” she remarks.
A member of the MIT physics faculty since 1964, Weiss was recognized as a devoted mentor and educator, in addition to being an earnest researcher.
“Rai’s creativity and perception as an experimentalist and physicist were legendary,” remarks Deepto Chakrabarty, the William A. M. Burden Professor in Astrophysics and head of the Department of Physics. “His no-frills approach and gruff demeanor concealed a profoundly close, supportive, and collaborative connection with his students, postdoctoral researchers, and other mentees. Rai was a true product of MIT.”
“Rai occupied a unique space in science: He was the architect of two disciplines — measurements of the cosmic microwave background and gravitational waves. His students have progressed to lead both fields while embodying Rai’s rigor and integrity. He not only pioneered significant scientific advancements but also cultivated individuals of exceptional caliber and honesty,” asserts Peter Fisher, the Thomas A. Frank Professor of Physics and former chair of the physics department.
Ushering in a new epoch in astrophysics
LIGO is a network of two identical detectors separated by 1,865 miles. By transmitting finely adjusted lasers back and forth through the detectors, scientists can sense disturbances caused by gravitational waves, whose existence was suggested by Albert Einstein. These findings shed light on ancient collisions and other occurrences in the early universe, confirming Einstein’s theory of general relativity. Currently, the LIGO Scientific Collaboration comprises hundreds of scientists at MIT, Caltech, and other institutions, and in conjunction with the Virgo and KAGRA observatories in Italy and Japan, forms the global LVK Collaboration — but five decades prior, the instrument’s concept originated as an MIT class project envisioned by Weiss.
As he shared with MIT News in 2017, during the inception of the idea, Weiss pondered: “What’s the simplest approach I can take to illustrate to these students that we could detect the impact of a gravitational wave?”
To bring this bold design to fruition, Weiss collaborated in 1976 with physicist Kip Thorne, who, inspired in part by discussions with Weiss, soon initiated the formation of a gravitational wave experiment group at Caltech. The two forged a partnership between MIT and Caltech, and in 1979, the late Scottish physicist Ronald Drever, then affiliated with the University of Glasgow, joined the effort at Caltech. These three scholars — who became the co-founders of LIGO — worked to refine the dimensions and scientific specifications for an instrument sensitive enough to detect a gravitational wave. Barry Barish later joined the team at Caltech, assisting in securing financing and completing the detectors.
Following backing from the National Science Foundation, LIGO commenced construction in the mid-1990s, establishing interferometric detectors in Hanford, Washington, and Livingston, Louisiana.
Years later, when he shared the Nobel Prize with Thorne and Barish for his contributions to LIGO, Weiss acknowledged that countless colleagues had contributed to advancing the quest for gravitational waves.
“The discovery has been the collective effort of myriad individuals, many of whom played key roles,” Weiss stated at an MIT press conference. “I perceive receiving this [award] as a symbol of the various other people who have dedicated themselves to this work.”
He added: “This prize, along with others granted to scientists, represents a societal affirmation of [the significance of] obtaining understanding about our surroundings through reasoned evidence.”
“While I have always been in awe of and guided by Rai’s inventiveness, integrity, and humility, I was most struck by his expansive vision and capability to navigate between diverse realms,” states Matthew Evans, the MathWorks Professor of Physics. “He could fluidly transition from the finest technical specifics of an instrument to the expansive vision for a future observatory. In recent years, as the concept for a next-generation gravitational-wave observatory evolved, Rai frequently visited my office, sharing ideas on how to advance the project on all fronts. These discussions encompassed quantum mechanics to global politics, and Rai’s insights and efforts have laid the foundation for what’s to come.”
A lifelong intrigue with challenging problems
Weiss was born in 1932 in Berlin. The family fled from Nazi Germany to Prague before eventually emigrating to New York City, where Weiss developed a passion for classical music and electronics, earning income by repairing radios.
He enrolled at MIT, then left school during his junior year, only to return shortly thereafter, taking a position as a technician in the former Building 20. It was there that Weiss encountered physicist Jerrold Zacharias, who motivated him to complete his undergraduate studies in 1955 and his PhD in 1962.
Weiss spent a period as a postdoctoral researcher at Princeton University within the renowned group led by Robert Dicke, where he conducted experiments to investigate gravity. He returned to MIT as an assistant professor in 1964, establishing a new research group in the Research Laboratory of Electronics focused on cosmology and gravitation research.
Weiss received numerous accolades in addition to the Nobel Prize, including the Medaille de l’ADION, the 2006 Gruber Prize in Cosmology, and the 2007 Einstein Prize from 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, in addition to being a member of the National Academy of Sciences. In 2016, Weiss was awarded 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 spouse, Rebecca; his daughter, Sarah, and her partner, Tony; his son, Benjamin, and his wife, Carla; as well as a grandson, Sam, and his spouse, Constance. Further details about a memorial service will be provided soon.
This article might be revised.