It seemed like business as usual for astronomer Julie McEnery when she got an alert last Aug. 17 from the Fermi Space Telescope about a gamma ray burst — brilliant flashes of light in the night sky strong enough to briefly outshine the sun. As the alert went out to other astronomers around the world, she sat back to wait for the data to download.
But this particular burst turned out to be special. It occurred less than two seconds after a powerful ripple in spacetime known as a gravitational wave reached detectors on Earth.
A half-hour later, McEnery received notice that a collaborative effort known as LIGO (Laser Interferometer Gravitational-Wave Observatory) had detected a telltale audible chirp in its data at about the same time, indicating a gravitational wave. McEnery, a project scientist with the Fermi telescope, understood the significance immediately: Only the collision, or merger, of two neutron stars could have produced this distinct combination of signals.
“Usually, science results emerge a bit more slowly as you analyze data and gradually realize you’re potentially onto something,” McEnery said. “But this was, like, boom! I couldn’t believe it was happening. It was the best morning ever.”
Ecstatic, she bounced down the corridors of NASA’s Goddard Space Flight Center in Maryland to share her excitement — only to find that most of her colleagues had left to witness the total solar eclipse a few days hence. But word quickly spread, sparking a mad dash to pinpoint the exact galaxy where the signals had originated.
That night, at Las Campanas Observatory in Chile, four astronomers with the Carnegie Observatories sifted through archives of images in 100 possible galleries, scrambling to get their analysis done in the 90 minutes before the sector of interest in the night sky shifted out of range. They found their prize in the first 15 minutes: Similar to the Fermi observation, their telescopes had picked up a spectacular “kilonova,” a massive burst of energy that behaves a bit like a high-powered strobe light. Based on that, scientists at telescopes all over the world were able to track the kilonova as it faded over the following weeks. All told, they collected as much data as possible in every possible wavelength of light (radio, infrared, visible, ultraviolet, X-ray and gamma-ray).
Working together, McEnery, the astronomers in Chile and more than 70 observatories joined LIGO in this unprecedented recording of a celestial event with both light (the kilonova) and sound (the gravitational wave). The discovery showed the full promise of so-called “multimessenger” astronomy, an approach that collects information about the cosmos from a diverse group of “messengers:” light (electromagnetic radiation), sound, and even ultralight subatomic particles known as neutrinos — the only element missing from the Aug. 17 event.
Yet the initial giddy excitement soon gave way to a harsher reality: how to fairly apportion credit among many thousands of ambitious scientists, representing dozens of different organizations, for such a monumental, multipronged discovery.
To those outside the scientific community, this might seem like so much petty bickering, a clash of egos over a major simultaneous discovery. But there is a great deal at stake, especially for younger scientists striving to make their names in a highly competitive field. Last August’s celestial collision was the kind of discovery that can make a career and bring coveted honors and awards, not to mention increased funding for future research. The first detection of gravitational waves, announced in 2016, won the 2017 Nobel Prize in Physics, and the neutron star merger could merit consideration for a similar high honor — a powerful motivation for scientists to lay as strong a claim as possible for their contributions to the discovery.
So conflicts were bound to arise. The LIGO team and its astronomy partners discovered this firsthand during the two-month span between August’s discovery and the official public announcement, as they toiled through the painstaking process of hammering out the details — and apportioning the credit. It required bridging two very different scientific cultures — the big physics of the LIGO collaboration on the one hand, and the loose collection of highly competitive small astronomy groups on the other — each with different norms, best practices, even different favored academic journals.
“Scientists are competitive people and they want credit for what they’ve done,” says Josh Simon, one of the four astronomers manning the telescopes in Chile that fateful night. For him, the politics got in the way of the joy of discovery. “I spent as much time dealing with politics and the fallout from various decisions as I did working on the science,” he says. “That is not how I enjoy spending my time.”
“We were all taken by surprise [by the discovery] and we weren’t as prepared as we could have been, but I don’t think we would have been any more prepared a year from now,” says David Shoemaker, an MIT physicist and spokesperson for the LIGO collaboration. “It takes the reality of the event to understand the dynamics and what kinds of things need to be taken into consideration.”
This was Shoemaker’s first direct contact with the astronomy community, and he chalked up most of the behind-the-scenes tension to growing pains as the collaborative LIGO effort moves from “being a demonstration tool to test general relativity to something that generates a lot of astronomical interest,” he says. In that sense, the neutron star merger was a useful test, offering insight into how such multimessenger collaborations should be handled moving forward.
Headquartered on a quiet, tree-lined street in Pasadena, the Carnegie Observatories have a long history of exploring the night sky, beginning with construction of the iconic Mount Wilson Observatory in 1904 and adding Las Campanas Observatory in 1969.
A few miles away sits the LIGO Laboratory, the collaboration’s Caltech outpost. Physicists spent 40 years building the LIGO detector, a pair of huge laser interferometers located thousands of miles apart in Washington and Louisiana. The device is capable of identifying faint ripples in spacetime – first predicted by Albert Einstein when he formed his general theory of relativity in 1917. The high-risk, high-reward venture finally is paying off spectacularly.
Culturally, however, the two scientific outposts are worlds apart. LIGO — along with its European cousin VIRGO — is a massive collaboration with thousands of scientists who have been working in sync for more than a decade. “We all work for the collective good, and sometimes that means we put our own interests in the back seat,” says David Reitze, LIGO Lab’s executive director.
“LIGO is a scientific endeavor that requires the synergy of many different minds working together,” Shoemaker says. “It takes more than a village. It takes a city to do this kind of science.”
In contrast, astronomers tend to cluster in smaller, independent groups, and they are fiercely competitive, vying both for limited funding and for precious time on the world’s limited number of telescopes. Being first to report a breakthrough observation is hugely important to most astronomers.
There were quite a few scientific “firsts” associated with August’s discovery. It was the first detection of gravitational waves from a neutron star merger and the first confirmation of a kilonova gamma ray burst, which in turn confirmed a long-standing theory about the origins of the heavy elements in the universe. More esoterically, it also confirmed that gravitational waves travel at the speed of light. “We’ve spent decades trying to detect gravitational waves from neutron stars, and we got it,” says Tony Piro, a Carnegie astronomer. “Decades trying to figure out gamma ray bursts, and we got it. Decades trying to figure out where heavy elements come from, and we got it. Decades trying to figure out what the optical counterparts would look like. They all came together with this one object. It’s incredible.”
The drive to establish priority was clearly evident in the Carnegie press release, whose headline blared, “We Saw It First!” — an indication, perhaps, that there might be a few ruffled feathers beneath the public show of collegiality. From a scientific standpoint, the gravitational wave arrived first, but astronomers spotted the gamma ray burst a good 30 minutes before LIGO verified its detection. “When you are telling the story about the science, it’s relevant that the gamma ray burst came 1.7 seconds after the gravitational waves,” McEnery says. “From the human story perspective, I think it’s very relevant that the gamma rays were identified first.”
That much is not in dispute. According to Simon, things got messy after he and his colleagues spotted the kilonova and identified the host galaxy. Five other teams detected the event in their images within the next hour, and it wasn’t clear whether those teams spotted the kilonova before or after Carnegie’s announcement. This in turn sparked a lively debate about how much credit the subsequent teams should receive. “I would say that there was a subset of the [astronomy] community trying to jockey for position more than is typical,” says Benjamin Shappee, who recently moved from his postdoctoral position at Carnegie to become a faculty member at the University of Hawaii. “That’s as diplomatic as I can put it.”
The debate over credit extended to who should be listed as authors on the primary omnibus paper describing the discovery. LIGO made a good-faith effort to be as inclusive as possible, but hackles were raised over how the collaboration defined what constituted a “unique” contribution or discovery. In the end, the omnibus paper had two tiers of co-authors. The first included the six groups deemed “the discoverers,” with the second tier comprised of those who did the follow-up work and analysis. Even so, “there were a lot of people in that second category who thought they should have been in the first category because they did make a first or unique contribution,” Reitze says.
Timing the release of all the papers associated with the discovery also caused some tension. LIGO to date has played its cards close to its vest when it detects a gravitational wave — borne out of an excess of caution, lest a false positive damage the collaboration’s credibility. Five months passed in 2016 before LIGO felt comfortable announcing its very first detection.
But the astronomers approached the claims of discovery differently. They were accustomed to announcing discoveries quickly, the better to stake a claim, of course, but also to maximize the community’s ability to follow up on the discovery. So they didn’t see the point of a delay — especially since rumors of the finding were already flying late last summer, and it wasn’t a particularly well-kept secret.
LIGO responded by fast-tracking, by its standards, the publication of the primary omnibus paper for Oct. 16, 2017. That set the various teams scrambling over the two months after the discovery to complete their analyses in time. Lack of sleep no doubt frayed nerves even further, adding even more stress to an already fraught process. “People got sick because they were working so hard on this,” Reitze says.
“It felt like at times we were speaking different languages,” Piro says, lamenting the lack of senior administrators capable of straddling the two communities to act as mediators. “LIGO didn’t have a real representative of the astronomy community to interact with, so they were getting pulled in all sorts of directions. At the time, it was pretty painful, but it all worked out in the end.”
Shoemaker acknowledges the need for better communication between LIGO and its partners in the future, expressing regret for his own role in the divisions. “The big mistake I made at the beginning was to have my ear caught by certain voices, and I think that generated a lot of ill will,” he says.
Shappee, the former Carnegie astronomer, would like to see more openness in the process on the part of LIGO, to give everyone a level playing field. “The end result will be faster detections, better data and better science,” he says. “It’s not always beneficial to individuals. I’ve been burned multiple times, but I think the gains still strongly outweigh the costs.” He just might get his wish. According to Reitze, there is now sufficient confidence in LIGO’s instruments that the collaboration will be able to begin announcing possible detections immediately to all of its partners.
In fact, preliminary discussions are underway to set up a loose consortium to handle the political wrangling — appointing teams to write the papers and providing editorial support as needed, as well as deciding who gets listed as authors and in what order. And Piro predicts there will be more consolidation among the various groups of astronomers in the future. Caltech already has a group called GROWTH (Global Relay of Observatories Watching Transients Happen) that aims to do just that for astronomers all over the world.
It remains to be seen whether any professional relationships have been permanently damaged by all the infighting. “The process left some hard feelings with people,” Reitze concedes. “Whether or not time will heal those hard feelings, I don’t know.” LIGO recently suspended operations to do some upgrades, which could give everyone involved a much-needed cooling-off period before the next big discovery.
Shoemaker, for one, feels optimistic. “Resolving those complications had great value,” he says. “There is a strong incentive for us to learn more about each other and to craft relationships that can be mutually productive going forward.”
SUPERSTARS OF SCIENCE
Since the dawn of humanity, humans have noticed the nearly perfect tableau of the night sky — the planets, sun and moon moving through a fixed arrangement of stars.
This unchanging background gave rise to the abstract notion of space. Absolute time was a way to measure the periodic movement. But in the 1910s, Albert Einstein proposed the radical idea that time and space were just two dimensions of a single deeper reality — that time and space were in some sense interchangeable, dependent on the observer’s frame of reference. Clocks and yardsticks would give different measurements; space and time could be stretched, contracted and exchanged in a very precise way.
This led to speculation that gravitational waves might exist, moving through the universe at the speed of light — ripples in spacetime. Could they be captured as minute changes in the fabric of space? Or as waves of advance and retard in the measurement of time?
On Feb. 11, 2016, the first gravitational waves were observed, the result of two black holes that merged about 1.3 billion light-years from Earth. The 50-year search to detect these faint events was a success.
The Nobel Foundation honored the discovery by awarding the 2017 Nobel Prize for Physics to three scientists: Rainer Weiss of MIT and Kip S. Thorne and Barry C. Barish of Caltech. Because Nobel rules allow only up to three individuals to share an award, the 2017 prize didn’t recognize the thousands of scientists who had worked on LIGO over the decades.
Indeed, when Thorne got the 2 a.m. call informing him about the Nobel, his initial response was disappointment. “I was really hoping they would give the prize to the entire LIGO team,” he says. “I thought it was inappropriate to give it to just three individuals, [because] regardless of how big our contributions were, they didn’t match the contributions of the entire team.”
The Nobel Prizes were chartered more than a century ago, at a time when science was a very individual pursuit. But many fields of science in the 21st century are collaborative, raising the question of whether it might be time to update the Nobel bylaws. Both Thorne and David Reitze, the LIGO Project’s executive director, believe a useful model might be the relatively new Breakthrough Prize, largely financed by Russian oligarch Yuri Milner, which honored the LIGO collaboration by dividing the prize money among more than 1,000 scientists. Then again, says Reitze, “Who am I to tell the Nobel committee what it should be doing?”