Our Man at LIGO
On September 14, 2015, Keith Thorne’s day began like any other. He awoke in his Livingston, Louisiana, house and ate his usual breakfast: half a grapefruit, cereal with bananas and almond milk, and coffee, black. He arrived at work about 8:30 a.m., expecting to settle into his usual routine in his usual workspace, which is situated between two giant, powerful lasers. At the right-angle nexus of those two lasers, which each stretch two and a half miles in two directions, Keith splits his time between the Control Room, where a dozen or so computers display graphs and numbers, and a smaller room, filled with racks of computer equipment connected by well-organized tangles of wires.
But before Keith could begin computer maintenance and software upgrades on that day, a colleague grabbed him with urgency, and said, “We may have a signal.”
Could it be real?
If it was, the great hopes of hundreds, if not thousands, of scientists would be realized. The $1.1 billion invested in the device would be justified. Albert Einstein’s 100-year-old prediction about gravitational waves and the very nature of our universe would be proven right. It would offer evidence of a mindboggling collision of two giant black holes, occurring 1.3 billion years ago. A collision that sent gravitational waves rippling through the fabric of space and time, reaching earth just that morning.
And if it wasn’t? Well then, it could be a fake signal, injected into the system as a test, or worse: by a hacker. Or, it could just be a fluke, an instrumental error perhaps, another small blip in the never-ending human quest for knowledge.
Never mind that most of us, citizens of the USA who had fronted taxpayer money for the device, were oblivious to this decades-long quest. Never mind that most of us had never even heard of gravitational waves. Never mind that most of us hadn’t even thought about gravity itself, that ever-present imperceptible but inescapable force that keeps us rooted to the ground, since high school science class. To the thousands of scientists working to prove or disprove Einstein’s predictions, this signal—if it was real—would change everything.
Just before 5 a.m., just a few hours before Keith arrived at work that day, automated systems triggered a notification system. A team of scientists monitoring the device’s data online in Germany saw something unusual, and then called the Livingston facility.
Around the world, other scientists working on the project saw the data on their screens. Transformed into an audible signal, it sounded like a brief low-to-high chirp. A visualization of the information showed a black graph with a bright blue-to-green-to-yellow up-swoop, like the tail of a cursive letter. Some scientists sat at their desks, whispering expletives. Others emailed and texted colleagues with exclamations of amazement. But virtually all tempered their excitement with skepticism. A number of things might have caused the signal, and there was no reason to celebrate until they knew for sure, until every other possibility was ruled out.
A flurry of activity engulfed the Control Room. “Paranoia set in,” says Keith. “You can’t calibrate an instrument like this with the black hole in your pocket.”
Keith was stressed. As the software engineer and the leader of the group that handles electrical engineering, information technology at the high tech site, and networking, he couldn’t relish the news of the signal and its potential big picture scientific meaning.
Over the following days, weeks, and months, Keith furiously and painstakingly documented the exact state of the instrument at the time the signal came through, like what computer programs were running and who was logged into which computer. He analyzed computer code line by line, he put on his cyber security hat and considered potentially malicious activity, and he responded to questioning from higher-ups. “I could have been a prime suspect,” he says, explaining that he would have known if someone had planted a fake signal. “I like to say it’s my graveyard and I should know where the dead bodies are.”
“Since we had a pre-arranged process to follow when a detection ‘candidate’ appears, we dug into the work,” says Joe Giaime, Keith’s boss and head of the facility. “Keith’s team is critical to the operation of the facility...Keith is a pro. He promises what he can deliver, and he delivers what he promises.”
Worldwide, the project scientists soon agreed that the signal and its scientific implications would remain a secret until they could say with certainty that this was the real deal. If they had to mention it, they would recite a vague response about ongoing tests and analyses. At the Livingston facility, a documentary film crew on site from NOVA was sworn to secrecy. At home, Keith didn’t tell his wife anything.
Scientists have been looking for gravitational waves since Einstein’s prediction in 1915. That was the year he published his Theory of Relativity, a theory that changed our concept of the universe from static to dynamic. Einstein posited that the universe morphed as matter changed into energy, and vice versa. But Einstein was conflicted about gravitational waves, alternately saying that they did and did not exist, and the search for gravitational waves has not been straightforward since then.
Keith joined the search for gravitational waves nearly ninety years later, in 2003, after years of his own personal trial and error to find his place in the science world. As a child of the sixties, Keith loved rockets and space exploration. He devoured science fiction books, and his parents—a father in industrial engineering sales and a mother who was a public health nurse—both encouraged his interest in learning. Becoming an astronaut was out of the question, since he wore glasses, so instead he followed his love of physics to the University of Michigan, and then began graduate studies at the University of Illinois, aiming for a PhD.
But he hit a roadblock. After stumbling through his first major round of graduate exams, he left the program with a Masters Degree in 1980 and moved to California to work at Hughes Aircraft.
Still, his love of research wouldn’t rest, and he decided to try again, this time working towards his PhD at the University of Minnesota and the famed Fermilab, the National Accelerator Laboratory outside of Chicago, the kind of place where physicists smash matter into the smallest pieces imaginable, to explore dark matter and learn what the world is really made of. By 1989, Keith had earned his PhD and married his sweetheart, Kathy, who he’d met at a science fiction convention.
But Keith’s successful run was coming to a close. A new and even more powerful particle accelerator was slated for construction in Texas, and Keith’s colleagues expected jobs there. It was too good to be true. When Congress cut the project’s funding, physicists flocked back to the Fermilab. Keith found himself out of work by 1994.
While Keith had his eyes trained on the smallest fragments of our world, a different K. Thorne, known as Kip, chased Einstein’s elusive gravitational waves. A theoretical physicist at Caltech since 1967, Kip first developed mathematical insights for gravitational wave theory and then, in the mid-1980s, began work with Ronald Drever and Rainer Weiss on the technical plans for a giant instrument that could detect them. After decades of work, the instrument, known as LIGO, the Laser Interferometer Gravitational-Wave Observatory, was funded in 1992. The point, Kip said recently in an interview, is not just to record a gravitational wave for the first time. The point is to open a new window into the universe and its secrets.
Ground was broken for two detectors, at opposite ends of the country, far enough apart to locate the signal, something like a pair of ears that can pinpoint the source of a sound. Each L-shaped detector housed two lasers, two and a half miles long, meeting in the middle at a right angle. Each laser beamed out and reflected back, perfectly in sync—unless some huge cosmic event emitted powerful gravitational waves, compressing and stretching space. Such a force would change the distance each laser travels, pushing them out of sync—by an infinitesimal, but measurable, amount, by just a tiny fraction of an atom. But only if the instrument worked. And only if Einstein was right.
At the time, Keith Thorne had not yet been pulled into gravitational wave research. Without work, he was lost and discouraged. But good fortune befell his wife, Kathy, a geographer. Mansfield University called out of the blue with a proposition: a professorship. She accepted, and Keith became the “trailing spouse,” following Kathy, now the breadwinner of the two, to Wellsboro, Pennsylvania. She built a successful career, taught classes in mapping, and studied how people use maps, get lost, and finally find their way.
Keith cast around for new opportunities. He set up a computer consulting business. He made friends and loved the town. But his career frustration grew.
“It was Sam Finn at Penn State who in 2003 took a chance on this a-bit-long-in-the-tooth research physicist to join LIGO,” Keith says. His previous work at the Fermilab had been “third or fourth generation” experiments, he says. Initial groundbreaking observations had already been made, and he felt he was just working on fine-tuning measurements. Gravitational wave research was different. No one had ever directly observed gravitational waves before. Here was a chance to be involved with something truly cutting edge. He spent the next five years commuting between Wellsboro and State College, at the very time the LIGO detectors, one in Livingston, Louisiana, and the other in Hanford, Washington, began collecting data that he, and other scientists around the world, could analyze.
By 2008, Kathy encountered health problems, and she had trouble keeping up with the demands of her position. She suggested that Keith start looking for a better job, and she retired from Mansfield University. Keith had intended to continue in basic research, and a job opportunity at LIGO turned up. But the interview process led away from hands-on research.
“Given the remote location of the LIGO sites, it can be hard to retain non-scientist staff, especially electronics and computer people,” Keith explains. “The Livingston facility had had trouble keeping someone in the software engineer’s position. In fact, the position had been vacant for months when I was applying to be a staff scientist. What I did not know was that the heads of both observatories, who were familiar with my work, had thought I would be ideal for it and had been figuring out how to get me to take such a position.”
So the Thornes moved from the northern end of the Appalachians to the southern edge (though they’ve still hung onto their Wellsboro house) and arrived in Louisiana in 2008, now with Kathy as the “trailing spouse.” The adjustment was not easy. Hurricane Gustav had just hit, displaced residents occupied all the rental properties, and houses were wrecked by fallen trees. The couple searched for high ground, and then built a house in the middle of a treeless hay field. Bookshelves lined the walls, full of science fiction, mysteries, food policy nonfiction, and more. Kathy began organic farming, growing more than two dozen vegetable crops for friends and colleagues. Not long after moving in, lightning struck the house, scorching the electrical system.
Keith settled into his office at the center of the LIGO facility, which was scheduled for a major upgrade. From 2010 until 2015, the device was shut down so that scientists could use what they had learned about the instrument during the first phase of the project to tweak it into perfection for the second phase.
To detect a change in distance 1/10,000th the width of a proton, without interference from a truck slamming on its brakes, or a power surge on overhead electrical lines, or the Gulf of Mexico’s tides, or the whoosh of Kathy’s bike as she rides the perimeter loop around the device, the lasers and mirrors are virtually isolated from earth itself. They are sealed in vacuum tubes, free of dust and debris, free from the vibrations of the earth. The lasers beam through the steel and concrete tunnels, into power boosters, until special mirrors beam them back. The mirrors are made of ultrapure glass, cylinders less than a foot in diameter and about four and a half inches thick, first manufactured by Corning, Inc. in Canton, New York—the same type of fused silica material used in the windshields of the space shuttle and space station—and then further polished and finished to exacting specifications.
According to Larry Sutton, Corning sales manager, “If you have ever looked through a regular drinking glass, what you are looking at is distorted pretty bad—with LIGO-grade fused silica, you could look through a part six feet thick and still read this text.”
The mirrors were hung by glass fibers and installed by people following “clean room” protocol: wearing gloves, hats or hairnets, nose and mouth masks, smocks, and booties. The hanging mirrors are hooked up to pendulums that dampen any external movement.
And then, in early September 2015, after all the upgrades, the extra-special noise-canceling materials, higher-power lasers, larger mirrors, and faster software, “Advanced LIGO” machine was up and running.
The official research run was not scheduled to begin quite yet. The data logbook had just been set up. One top research scientist wanted to turn the machine off and make more adjustments. But the facility staff said the machine was ready.
Days later, the fateful signal registered. And after all the double checking and second guessing, after the cross checking between Washington and Louisiana, after all the data and the findings moved their way up through the hierarchy of scientific committees in formal procession, the more than one thousand scientists, building on the trial and error of the past 100 years, were ready to make their announcement on February 11, 2016. The secret was revealed.
Gravitational waves had rippled toward earth, and passed through the LIGO detectors, stretching and compressing the instrument, just as the same waves rippled through all of our bodies, undetected. The signal is evidence of a massive event, 1.3 billion light years away, 1.3 billion years ago, a collision of two black holes, one twenty-nine times the mass of the sun, the other thirty-six times, circling each other until they collided into one, somewhere beyond the Southern Hemisphere. A collision so strong that it transformed a mass three times that of our sun into gravitational waves.
But the signal detection is evidence of even more. It’s evidence of a massive human collaboration on earth, and it’s evidence of billions of tasks completed by more than one thousand people, all seeking to understand the essence of space and time, the universe itself, and their place in it. And scientists say that this is just the beginning. More secrets are sure to reveal themselves with this tool’s help.
Increased demands on the instrument, now that it has proven its value, have kept Keith busy and on-call. But he manages to spend weekends fixing Kathy’s tractor and building greenhouses and hoop houses for the farm. “It keeps me humble,” he says. “I should be more exuberant about this discovery, but it’s been slowly sinking in for months now. I talk about it calmly, but when I stop to think about it, it’s really quite amazing.”