We live in a Universe that is, in parts, distinctly warped.
It’s a feature that has intrigued Prof Kip Thorne for much of his stellar career.
From violent black holes to gravitational waves that wobble through the Universe and the potential of wormholes as plunging “shortcuts” through space-time, Thorne’s insights have enlightened scientists, artists and the general public.
The Nobel laureate is to deliver the Royal Irish Academy 2025 Hamilton Lecture, about how he fell in love with objects and phenomena from the warped side.
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A black hole is the quintessential example of warped space-time, says Thorne, whose research at the California Institute of Technology (Caltech) has helped to describe many features of these strange spaces.
“The surface of the black hole is called the horizon, and if you fall through it, you can never get out,” he says. “As you approach the horizon, time is warped, it slows compared to time far away, then inside the horizon, time flows towards the centre.”
As black holes spin, they drag space into a whirling, tornado-like motion around themselves, and tentacle-like extensions reach out, grabbing and tearing things apart by squeezing and stretching them.
“It’s quite amazing that these phenomena are made from warped space-time, there’s no matter involved in them at all, and at the hole’s centre laws of quantum gravity take over,” Thorne adds. “Only in recent decades have we been in a position to begin to understand this warping in detail.”
Waving to Einstein
Motivated by a desire to understand more about how space-time behaves, Thorne was one of the founders of LIGO, the Laser Interferometer Gravitational-wave Observatory, a large-scale project to detect gravitational waves, or ripples in space-time.
Take, for example, when two black holes collide. This creates a “storm” in the shape of space and in the rate and flow of time, he says, which in turn produces gravitational waves.
Albert Einstein had predicted such waves in 1916 through his General Theory of Relativity, and almost a century later in September 2015, LIGO first observed the phenomenon directly.
When the signal first arrived, Thorne and others were sceptical.
“We were all very cautious when we saw the signal,” he says of that moment just over a decade ago.
“The new generation of instruments LIGO was using were more sensitive, and the signal that came through was very strong. And you don’t want to go out and announce that we have evidence for gravitational waves unless you are absolutely sure.”
One concern was that the system had been hacked, but a thorough investigation of the data channels revealed no “fingerprints” of human interference, and the team announced the major breakthrough.
Since then, LIGO has detected about 300 incidences of gravitational waves, and in 2017, Thorne, Barry Barish and Rainer Weiss were awarded the Nobel Prize in physics for their contributions to the discovery.
So what led Thorne, born in Utah in 1940, on the quest to discover more about space? It was due in part to some chalk, a pavement and the encouragement of his mother, he recalls.
“I was eight years old, and my mother took me to a lecture about the solar system, where I learned about the planets and the sun, and I was just totally fascinated. So she then sat down with me and she said, look, let’s make a model of this.”
They chalked out a metre-diameter picture of the sun on a pavement near their house, then they mapped out and drew the planets and their distances from the sun, to scale.
“It was just amazing to me the enormous distances between the sun and the planets,” he recalls. “Pluto, which was still a planet in those days, was not even in our town, it was out in the neighbouring town.”
That exercise sparked Thorne to find out more about the Universe, and to study physics at Caltech, where his ability to form mental images helped him to forge ahead.
“Mental images are the foundation for physical intuition,” he says. “The laws of physics are written in the language of mathematics. For me, mathematical calculations are slow and laborious but the mental imagery allows me to move forward quickly.”
It’s an approach that he shared with his close friend, Stephen Hawking.
“That intuition, for Stephen and for me, is based on visualisations that summarise in pictures what the mathematics is trying to tell us, and most of the time when I’m doing physics, I’m working with those pictures,” he says.
“Then to be sure that what I’m figuring out is right, I go to the mathematics, I slow down and get something that is more rigorous and more secure.”
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Thorne has applied this visual approach to his work in Hollywood, which grew from a date with film-maker Lynda Obst set up through their mutual friend, scientist Carl Sagan.
“The date didn’t work out romantically, I was too nerdy for her and she was too intense for me, but we became very good friends,” Thorne says.
When Obst asked him to brainstorm on a movie, Thorne saw it as a way to inspire people about the Universe. Their initial ideas grew into Interstellar, the 2014 film starring Matthew McConaughey and Anne Hathaway and directed by Christopher Nolan.
The story sees humans travel to a distant galaxy to explore potentially habitable planets, and most of it is based on sound science, according to Thorne.
“My agreement with Nolan was that nothing in the movie would violate well-established physical laws, and all wild speculation would spring from real science motivation, to the extent it didn’t get in the way of making a great movie,” he says. “We were able to achieve that goal except for one place.”
That place was the explorers’ trip through a wormhole to reach the distant galaxy.
Wormholes burrowing between folds in space-time have not been detected, and they would probably pinch off before reaching another galaxy, notes Thorne.
“I worked with the visual effects team, who produced a very accurate depiction of what it would be like to go through the wormhole if it does not pinch off, but when Christopher Nolan saw the videos, he told me there was a problem, that it looked too boring,” Thorne recalls. “I said here and only here abandon scientific accuracy, and use artistic licence.”
Thorne remains impressed at how otherwise faithful the movie is to science, and he credits the visual effects team who worked with him to render imagery of what the vicinity of a black hole would look like.
“In the vicinity of a black hole, the tidal forces pull the light rays apart to such an extreme degree that you can’t produce good images and you can’t make good videos by standard computer graphics techniques, so we had to invent whole new ways to do the visualisation,” he says. “We published our techniques in a physics journal, and we used them to explore in graphic detail how light behaves in the vicinity of black holes.”
Choose fun
Thorne continues to explore the warped side of the Universe with artists, and recently brought out a book with Lia Halloran that blends his poetry with her paintings. He describes the process as “enormous fun”, and he sees fun and excitement as important drivers of a person’s work.
“I always say to young people to pick a direction for work that is really fun,” he says.
“Because to have real impact requires working extremely hard, and if you’re not having fun at the same time, it will likely be impossible to work hard enough to achieve what you want to achieve.”
Thorne also embraces the power of science to explain the Universe and create technology for human benefit.
“Those of us who lived in the era before vaccines for childhood diseases such as polio and measles have seen the power of science to make the world a better place to live,” he says. “It was inspiring, and I have been very fortunate to get to work in science.”
The annual Hamilton Lecture celebrates achievements of Irish mathematician William Rowan Hamilton and is hosted by the Royal Irish Academy in association with Ibec and The Irish Times. Thorne will deliver the 2025 Hamilton Lecture on October 16th. The sold-out lecture will be available to watch back at ria.ie
