One summer circa 1970, Rainer Weiss holed up in a closet-size room in Building 20 — the infamously rickety, asbestos-coated, World War II-era makeshift wooden structure at the Massachusetts Institute of Technology that hosted countless discoveries and nine eventual Nobel Prize winners before being torn down in 1998 — and developed the basic design for an experiment that, nearly half a century later, would astound the world by detecting minuscule ripples in the fabric of space and time coming from the faraway collision of two black holes.

Along with the physicists Kip Thorne and Ron Drever, Weiss founded the Laser Interferometer Gravitational-Wave Observatory (LIGO), the experiment that in February 2016 announced the discovery of those ripples, or “gravitational waves,” which were first predicted in 1916 by Albert Einstein.

“The idea for using timing of light between free masses to detect gravitational waves occurred to me while teaching a course in general relativity at MIT in 1967,” Weiss told Quanta in an email. His students had heard about the physicist Joe Weber’s claim to have detected gravitational waves in the vibrations of huge aluminum bars. “I had trouble understanding the concept, and [instead] presented them with a gedanken experiment consisting of measuring the time it takes for light to travel between two free masses as the gravitational wave passes,” alternately stretching and compressing space-time as it goes. “It is a fairly simple problem to calculate the change in time due to the gravitational wave. It is, however, an almost impossible experiment to actually do with sufficient sensitivity.”

Weber’s claim proved erroneous, and Weiss returned to his timing idea to see if it was at all feasible to detect such tiny temporal fluctuations in a real measurement. “That is when I would go to a little room in Building 20 (the ‘Plywood Palace’) far from the telephone and near real apparatus to think about the different noise sources that would limit such a technique,” he said. “After a summer of stewing and estimating, it seemed that one could make an instrument with low enough noise, such as a laser-driven optical interferometer with arms on kilometer scales, that could intersect the estimates for gravitational waves from astrophysical sources. Next came an experimental prototype to show that the calculations were not crazy.” Then came the two giant L-shaped detectors of the LIGO experiment, which Weiss helped build and is still fine-tuning today.