Kip Thorne and the email that foreshadowed his Nobel Prize
After a lifetime hunt, the theoretical physicist was part of the team that made the first detection of a gravitational wave. He speaks exclusively to Andrew Masterson.
Although not a property exclusive to human beings, the ability to delay gratification is nevertheless a foundational characteristic of our species – the smart members of it, anyway. And Kip Thorne, Feynman professor emeritus at the California Institute of Technology in the US, is very smart indeed.
As a highly respected theoretical physicist, and joint founder in 1984 of the Laser Interferometer Gravitational-Wave Observatory (LIGO), Thorne could have been forgiven for giving way to a rush of excitement on one particular morning when he opened his computer.
“I had an email that said go look at a particular internal LIGO website, we may have a gravitational wave detection,” he recalls.
Thorne, however, has been a hardcore physicist ever since he was awarded his first degree back in 1962. Physics, like all science, is based on doubt, on demanding evidence and then testing it to breaking point.
This is especially so in the matter of gravitational waves – ripples in space-time predicted by Einstein in his Theory of General Relativity, and the principal focus of Thorne’s entire career. The existence of the waves is well supported theoretically, but theory without evidence will always be suspect.
Perhaps, as he looked at the email that morning, he had a fleeting memory of another American physicist, Joseph Weber, who claimed in 1970 to have detected gravitational waves, only to have his work discredited.
The stakes were high. A premature announcement could well result in professional disaster. Rushed reveals in physics can backfire badly, as in 2011 when scientists at the Oscillation Project with Emulsion-tRacking Apparatus (OPERA) project based at CERN announced they had observed neutrinos travelling faster than light, only to discover the result was produced by an improperly attached fibre optic cable and a clock ticking too fast.
And at first blush, when Thorne did in fact look at the internal website, his reluctance to credit the claim appeared wise.
“I looked at it,” he says, “and the data were almost too good to be true. I was suspicious, and I think essentially everybody else was suspicious, too, because the signal was rather strong and it was quite perfect and it was in such beautiful agreement between the two detectors.
“We had expected that our first signal would be so weak that you would not be able to see it beneath all the noise. We did not think that we would be able to see it by eye in the raw data – but this we could. We were very cautious.”
So Thorne and his colleagues embarked on a long and exacting examination of the mechanics of the detection.
“It was not until after several months,” he says, “when the best experts on the instruments had gone through a large number of auxiliary data channels that told us what’s going on inside the instrument, and had seen that there was absolutely nothing wrong in there, and absolutely no evidence that we had been hacked, it was not until then that I began to firmly believe this was real.”
And it was then, and only then, that he permitted his long-delayed gratification free rein.
“At that point, my own reaction was just a sense of profound satisfaction,” he says.
“I had put something like 60% of my career research efforts into this and I had made the right bets, and pushed in the right directions. It was just great satisfaction.”
It was also a straight run to a Nobel Prize, which he shared in 2017 with fellow LIGO founder Rainer Weiss, and Barry Barish, one of the project’s principal investigators, “for decisive contributions to the LIGO detector and the observation of gravitational waves”.
But, unlike some other theoretical physicists at the top of their game, Thorne has maintained a relatively low public profile. His forays into popular culture have been modest, if consequential. Years ago, he threw ideas about wormholes at Carl Sagan which ended up in Sagan’s bestselling novel (and the subsequent Hollywood film), Contact.
More recently, he collaborated with movie producer Lynda Obst to develop the theoretical framework for the Christopher Nolan feature, Interstellar, and also wrote the accompanying book.
And now, he’s embarking on a public speaking tour in Australia, called What’s Next?, sharing the stage with the Royal Institution of Australia’s lead scientist, astronomer Alan Duffy, and British comedian Robin Ince (co-host, with Brian Cox, of the BBC radio show The Infinite Monkey Cage).
No doubt his work on gravitational waves will be much to the fore in the shows, but his secondary field of interest – time travel – is likely to be a popular audience topic.
Across several books and papers over the years, Thorne has pondered the theoretical possibilities that wormholes – an idea arising from Einstein’s work, that describes tunnels between two widely separated points in space – could be used for travel through space and time.
One problem with this, of course, is that wormholes may not exist – a matter he conceded in his 2014 Interstellar tie-in, when he wrote, “We see no objects in our universe that could become wormholes as they age.”
On the other hand, perhaps they are there and we simply haven’t seen them yet. Or perhaps they are too small to see – Thorne suggests that tiny wormholes might exist within a possible cosmological structure he calls “quantum foam”.
The mundane matter of existence aside, however, there is no question that wormholes and time travel both exercise the imaginations of a lot of science fiction writers. And in this respect, Thorne’s calculations spell trouble.
A favourite trope of sci-fi is the “grandfather paradox” – the notion of a man who travels back in time and (accidentally or otherwise) kills his own grandfather, thus obliterating his own existence.
In work published as early as 1991 (although clearly not read by the writers of Red Dwarf and Dr Who) Thorne and fellow researchers showed that such paradoxes would not – indeed, cannot – arise, permitting instead an infinite number of other possible outcomes.
His findings were used by US science fiction author Larry Niven for his short story collection Rainbow Mars. The dashed hopes of myriad other writers, however, are of little concern to Thorne. All that really matters is the outcome of the research.
“I don’t think that I and my collaborators have actually proved that such effects cannot arise, but I do think we’ve provided strong evidence,” he says. “I think we have an understanding of why they can’t arise.”
You get the feeling that for all his comparatively low public profile, Kip Thorne is a man who enjoys pushing ideas as far as they will go. In 1975, for instance, he and astronomer Anna Żytkow suggested that it is entirely possible for a small dense star to fall into a very big not-so-dense one and survive intact, producing a star-within-a-star. He called the theoretical result a Thorne-Żytkow Object (TZO).
In 2014, a team of astrophysicists led by Emily Levesque at the University of Colorado at Boulder announced it had found one.
At which point, Thorne had another of those delayed gratification moments.
“Certainly, in any piece of research that I’ve done where I have a new result that I don’t think anyone has seen before, I also feel a sense of satisfaction,” he says.
“But not at the level of the discovery of gravitational waves. That’s a level of satisfaction that goes far beyond anything I’ve ever experienced before in my life.”