In 1976, a theoretical physicist pushed Caltech toward building a machine to detect Einstein’s gravitational waves - 39 years later, black-hole-hunting LIGO heard their ripples, and by 2017, the Interstellar science adviser wept before the man who predicted them while receiving the Nobel Prize

Physicist Kip S. Thorne stood at one of the defining moments of his scientific life in 2017. As the American scientist collected the Nobel Prize in Physics, he was overcome with emotion upon seeing an image of Albert Einstein, the man whose century-old prediction had set Thorne on a journey that would consume much of his life.

He had spent most of his careerchasing something humanity had never seen: gravitational waves, the ripples in spacetime predicted by Einstein's theory of general relativity. And by the time Thorne received the Nobel Prize in 2017, those ripples had finally been detected, thanks to the enormous scientific effort behind LIGO, the massive black hole hunting machine.

But the path to that emotional moment in Stockholm had begun more than half a century earlier, and, at one point, the field Thorne chose was considered by many leading scientists to be a scientific dead end.

In 1961, Kip Thorne decided to chase Einstein's universe

Thorne's fascination with physics began early. As a teenager, he discovered George Gamow's One, Two, Three, … Infinity, a book that introduced him to astronomy, mathematics and Einstein's relativity. He read it three times and decided he wanted to become a physicist.

By his fourth year at Caltech, Thorne had chosen general relativity as the subject he wanted to pursue. But it was hardly an obvious career choice. According to his own scientific biography, many prominent physicists and astronomers of the era believed relativity had little practical future. One of his mentors even considered it a “dead end,” with the expansion of the universe seen as its only significant application.

Thorne disagreed. At Princeton, he entered the world of black holes, neutron stars and curved spacetime under the influence of physicist John Archibald Wheeler. Then, during a summer school in the French Alps in 1963, he encountered gravitational waves in depth for the first time.

In the 1970s, the dream became a machine

Einstein predicted gravitational waves in 1916 as part of his general theory of relativity, but detecting them was an entirely different challenge. Their effects on Earth were extraordinarily small, requiring instruments capable of measuring unimaginably tiny changes in distance.

During the 1970s, Thorne became convinced that gravitational-wave detection was possible. Discussions with experimental physicists Vladimir Braginsky and Rainer Weiss pushed him toward an idea that would eventually transform astronomy.

In 1976, Thorne proposed that Caltech establish a research group devoted to gravitational-wave experiments. The university invested millions of dollars in laboratories and a prototype interferometer with 40-meter arms, an early step toward what would become one of the world's most ambitious scientific instruments.

Then came 1984. Thorne, Weiss and Ronald Drever founded LIGO, the Laser Interferometer Gravitational-Wave Observatory, as a Caltech-MIT collaboration. Thorne later described himself as the “glue” holding together the collaboration during its difficult early years, mediating between scientists with very different personalities and working styles.

The machine they were trying to build would effectively become humanity's new sense organ, a way of listening to violent events in the universe through distortions in spacetime itself.

In 2015, the universe finally answered

After decades of theoretical work, engineering, failed expectations, prototypes and increasingly sophisticated detectors, LIGO finally made history on September 14, 2015.

Gravitational waves had been detected for the first time. The signal came from the collision of two black holes, confirming a prediction Einstein had made about a century earlier and opening an entirely new way of observing the universe. Thorne was among roughly 1,000 physicists involved in the achievement. Two years later, he shared the Nobel Prize in Physics with Rainer Weiss and Barry Barish for decisive contributions to the LIGO detector and the observation of gravitational waves.

And that was when the decades came flooding back. Looking at Einstein's image while receiving the Nobel medal, Thorne wept.

But before the Nobel tears, there was Interstellar

Thorne's journey through black holes and warped spacetime had also taken an unexpected detour, into Hollywood. After formally retiring from Caltech in 2009, he began devoting much of his time to collaborations between science and the arts. The most famous result was Christopher Nolan's 2014 film Interstellar.

For Thorne, the film was another way of doing what gravitational-wave science had always represented for him: helping people imagine the strange and powerful universe described by Einstein's physics. His later work also included collaborations with artists, musicians and filmmakers, driven by a desire to inspire non-scientists and young people with the beauty of science.