When visual-effects artist Paul Franklin accepted the Oscar in February for his work on the hit movie Interstellar, he gave thanks to the many explorers of science “who show us the universe in all its amazing and terrifying beauty.” Franklin made it a point to single out physicist Kip Thorne *65 for special recognition, calling him “one of the smartest people on Earth.”
Thorne never planned to attend the Oscar ceremony, or even to watch it, though he finally relented and watched at a friend’s house. He’s not much of a movie buff, he confesses, and is knee-deep in another project, rechecking each and every formula in a 1,300-page physics textbook he has co-authored. A 74-year-old professor emeritus at the California Institute of Technology, Thorne has been a driving force on a project that may for the first time detect the presence of gravitational waves, which are caused by warps in the four-dimensional space-time described in Einstein’s theory of general relativity. And he has another movie in the works.
Interstellar, which was nominated for five Academy Awards, has grossed more than $225 million worldwide, but what has provoked the most attention is its determination to treat complicated scientific concepts seriously. The film concerns mankind’s desperate attempt to find habitable planets in other galaxies, a search that leads through wormholes and around black holes, exotic features of the universe that Thorne has spent much of his career studying. It was he who wrote the elaborate mathematical equations that enabled filmmakers to create them digitally on the big screen. To coincide with the film’s release, Thorne published a companion book, The Science of Interstellar, which explains the outer reaches of theoretical physics with a clarity that even a layman can follow.
Over the last half-century, Thorne has worked with many of his field’s most respected figures, including his mentor, the late Princeton professor John Wheeler; his former colleague Richard Feynman *42; and his friend Stephen Hawking. In recognition of his recently broadened portfolio, though, Thorne’s puckish Caltech assistant has updated the nametag outside his office door. It now reads:
Kip S. Thorne
The Feynman Professor of Theoretical Physics, Emeritus
“Mogul” would be overstating things, as Thorne himself would be the first to say. But since Interstellar has served as Thorne’s vehicle for introducing cutting-edge physics to the general public, it may also be a good vehicle for introducing the public to him.
Thorne says his tuxedo that evening in 1980 was baby blue; Hollywood producer Lynda Obst, his date to the premiere of Carl Sagan’s television science series Cosmos, remembers that it was maroon. Whichever it was, neither color did him much credit, nor did the peace-sign medallion he wore with it. “Fabulous guy,” Obst thought. “Needs a stylist.”
Obst and Thorne didn’t work out as a couple, but they remained close friends with each other and with Sagan. When Sagan wanted one of the characters in his 1985 novel, Contact, to traverse the galaxies through a black hole, he first ran the idea past Thorne. It won’t work, Thorne told him: Have her use a wormhole instead. When Obst, a self-described “physics geek,” had an idea in 2005 for the science-fiction movie that would bec0me Interstellar, she knew whom to call to deal with the science. Then she arranged several meetings with Steven Spielberg, who liked an eight-page treatment and tentatively agreed to direct the film.
Jonathan “Jonah” Nolan signed on to polish the script and Paramount Pictures agreed to produce it, but the long 2007 Hollywood writers’ strike stopped everyone’s momentum. By the time the writers returned to work, both Nolan and Spielberg had dropped out for other projects. Into this gap stepped Nolan’s brother, Christopher, fresh off a huge commercial success directing The Dark Knight, who agreed both to direct and to finish the still-imperfect screenplay.
At his first meeting with Spielberg, Thorne proposed two rules that would govern the making of Interstellar: Nothing in the plot could violate the laws of physics, and any speculations about physical laws that might still be imperfectly understood would nevertheless be grounded in principles that — as he later put it in his book — “serious physicists would at least discuss over a beer.”
Nolan also agreed to Thorne’s principles, and over the next several years the two consulted, argued, and compromised as the film moved through production. Thorne “saw his role not as science police, but as narrative collaborator,” Nolan wrote in a foreword to Thorne’s book, “scouring scientific journals and academic papers for solutions to corners I’d written myself into.” The only time they came to loggerheads was when Nolan insisted that he needed a character to be able to travel faster than the speed of light. Though it took several weeks, Thorne finally convinced him that such a thing was impossible, and the director backed down.
When it came time to make the movie, Thorne worked just as closely with Franklin, who already had won a visual-effects Oscar for Inception. Black holes emit no light and wormholes have never been proven to exist. What did those things look like and how would they behave in the real world? Thorne spent months writing mathematical formulas to estimate, say, how a black hole’s gravity would bend light from other objects. He then sent them to Oliver James, the film’s chief scientist and an atomic physicist in his own right, who would convert the formulas into computer code and pass it on to engineers who transformed the code into visual images. Some of those images took up to 100 hours each to create. The entire film contains a massive 800 terabytes of data.
“You cannot imagine how ecstatic I was when Oliver sent me his initial film clips,” Thorne writes in his book. “For the first time ever — and before any other scientist — I saw in ultrahigh definition what a fast-spinning black hole looks like.”
Two of the film’s stars, Matthew McConaughey and Anne Hathaway, peppered him with technical questions to help them prepare for their roles; Michael Caine, who plays a physicist, grew a beard to look more like Thorne. When it came time to film scenes in the Caine character’s office, blackboards in the background were filled with actual formulas for the theories the characters were discussing, all meticulously written in Thorne’s own hand.
While some reviewers and scientists criticized parts of the movie as far-fetched, Thorne believes that misses the point. Interstellar is not a documentary, so some dramatic license was unavoidable, but he insists that the underlying physics is conceptually sound. Science writers, Dennis Overbye noted on his New York Times blog, “have paid the movie the ultimate compliment: taking it seriously enough to subject it to a kind of public peer review.” Michio Kaku, a theoretical physicist at City College of New York, told CBS News that the film “could set the gold standard for science-fiction movies for years to come.”
For Interstellar’s London premiere last October, Obst might have seemed like an obvious choice to be Thorne’s date, but he invited someone else: Stephen Hawking, his friend for nearly half a century. Several weeks later, Hawking returned the favor by inviting Thorne to be his date to the London premiere of The Theory of Everything, the movie about Hawking’s life.
The science underpinning Interstellar, combining elements of Newtonian physics, general relativity, quantum physics, and quantum gravity, flows from research Thorne has pursued for decades.
Born in Logan, Utah, he came from an academic family — both of his parents were university professors, as are two of his four siblings — but he jokes that his earliest ambition was to drive a snowplow. When he was 8, though, Thorne’s mother took him to a lecture on the solar system and then helped him draw a scale model of it on the street outside their house.
By the time he was 13, Thorne had decided that he wanted to study general relativity, and as an undergraduate at Caltech he took Feynman’s legendary “Physics X” course, so named because it wasn’t listed in the catalog. Instead, every other week Feynman would set up in an empty lecture hall and talk about whatever topics the students, down to the lowliest freshman, wanted to discuss.
“He was so good that he could give a polished lecture about any question that you wanted to raise,” Thorne recalls. Later, when they both served on the Caltech faculty, Feynman became “the person I would go to when I thought I had a good idea, to see if he could tear it apart.”
It was in graduate school at Princeton, studying under John Archibald Wheeler, that Thorne became interested in black holes. Wheeler, the longtime Joseph Henry Professor of Physics, had worked with everyone from Albert Einstein to Enrico Fermi and is credited with adding the terms “black hole” and “wormhole” to the scientific lexicon. Colleagues and students admired his ability to deliver elegantly detailed lectures without notes.
Thorne remembers Wheeler as a “phenomenal mentor” who had “tremendously good sense as to how much guidance a person needed and how long a person needed to flounder.” In 1967, at the age of 27, Thorne became one of the youngest tenured professors in Caltech’s history and six years later joined Wheeler and Charles Misner *57 in writing Gravitation, a textbook so influential that it is still often cited as “MTW,” after the authors’ initials.
Throughout his career, Thorne has tried to emulate his mentors when working with his own graduate students. Frans Pretorius, now in Princeton’s physics department, was one of Thorne’s postdocs from 2002 to 2005 and says Thorne would convene weekly groups of undergraduates, graduate students, and sometimes interested faculty members at which the participants could discuss their latest projects and share ideas. Some of these sessions could run as long as five hours.
“What really impressed me was how he could juggle so many different people,” Pretorius recalls. “There would easily be 20 people there, and he could intellectually manage all of them.”
In one significant respect, though, Thorne and Wheeler were temperamentally different. Wheeler’s inquiries in his later years sometimes took an almost philosophical turn. Such questions, Thorne admits, “always left me a little cold” — he describes himself, rather, as “more of a nuts-and-bolts engineer.” In his view, there are many different ways to describe what goes on in the universe: “The issue of which is the ‘true’ one is a meaningless issue.”
Thorne first met Hawking at a conference on general relativity in London in the summer of 1965. Thorne had just finished defending his Ph.D. thesis, and Hawking, who was still working on his and beginning to show signs of ALS, gave a presentation in which he applied Roger Penrose’s theories in differential topology to the operation of black holes. “It was a very impressive talk, and it was a new direction that nobody had done before,” Thorne recalls. They bonded while chatting afterward in the hall — grad student to grad student — and still get together several times a year. “We talk about life, not much about physics,” Thorne says.
Although the two never have collaborated professionally, they have made two famous wagers, both of which Thorne won. The first, made in 1974, concerned whether Cygnus X-1, an X-ray source in the constellation Cygnus, was in fact a black hole. If it could be proven that Cygnus X-1 was not a black hole, Thorne would buy Hawking a subscription to the satirical magazine Private Eye. If Cygnus X-1 was a black hole, Hawking would buy Thorne a subscription to Penthouse. Hawking conceded the bet almost 16 years later and paid up.
In 1991, Hawking bet Thorne and his Caltech colleague, John Preskill, £100 that the laws of physics prohibit the existence of singularities (points of infinite density at a black hole’s core) outside the black hole’s event horizon, the point beyond which nothing can escape the black hole’s gravity. Six years later, after a University of Texas postdoc showed that such “naked” singularities could be created in a computer simulation, Hawking again conceded — “on a technicality,” he said, because he had wanted to know if they could occur naturally.
Such diversions color a career that has placed Thorne among the forefront of theoretical physicists. In addition to describing the structure and behavior of black holes and wormholes, in 1977 he and Polish astrophysicist Anna Żytkow predicted the existence of red supergiant stars with smaller neutron stars at their core, oddities now known as Thorne-Żytkow Objects or TŻOs. Last year, astronomers announced that the star HV 2112 might be the first TŻO ever discovered.
It may be, however, that Thorne’s most important contribution will come over the next several years, as the Laser Interferometer Gravitational-Wave Observatory project (LIGO) becomes fully operational. Thorne co-founded LIGO in 1984 and joined his colleagues in convincing the National Science Foundation to build two huge observation stations, in Washington State and Louisiana, which it is hoped will detect the presence of gravitational waves rippling across the cosmos.
Einstein posited nearly a century ago that large gravitational disturbances — such as a collision of black holes, a pair of neutron stars orbiting each other, or even the Big Bang — would send out gravitational waves like ripples on a pond, warping space-time itself. There is strong observational evidence that these waves exist — former Princeton professors Joseph Taylor and Russell Hulse shared the 1993 Nobel Prize for measuring changes in the orbits of neutron stars caused by gravitational waves — but their presence never has been directly observed or measured. When LIGO’s instruments are tuned to their full sensitivity within the next few years, they will be able to measure quivers in the fabric of space-time as minute as one ten-quadrillionth of an inch, or one-thousandth the diameter of a proton. Gravitational waves also will give scientists detailed information about the space-time of black holes and whether they look the way Einstein’s theories predicted.
LIGO might make it possible to observe the chaos in space-time that results when two distant black holes collide. Wheeler, always a gifted phrasemaker, dubbed those wild oscillations “geometrodynamics.” It bothered him that we knew so little about how warped space-time behaves, or why, and he urged his students to strike out into this scientific unknown.
“We tried, and failed miserably,” Thorne writes in his book. “We didn’t know how to solve Einstein’s equations well enough to learn their predictions, and we had no way to observe geometrodynamics in the astronomical universe. I’ve devoted much of my career to changing this.”
Thorne retired from Caltech in 2009 but still keeps an office there, which he visits occasionally to consult with colleagues and participate in a research program trying to understand the nonlinear dynamics of curved space-time. On a warm February afternoon, clad in a Hawaiian shirt, jeans, and Birkenstocks, he talked about his next projects.
He and Obst are collaborating with Hawking on a new movie venture. They have written nine drafts of a treatment and begun talking to a screenwriter, but won’t discuss the plot except to say that it concerns cosmology — the study of the origins and fate of the universe.
Another topic that has long interested Thorne is whether backward time travel is possible. Hawking insists that the laws of physics forbid it; Thorne isn’t so sure. If they can ever agree on the terms and conditions, they are thinking about another bet.
Mark F. Bernstein ’83 is PAW’s senior writer.