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Cottrell Scholar David Reitze’s LIGO Adventure

The dust has settled after the detection of the universe-shaking kilonova, and David Reitze, executive director of the Laser Interferometer Gravitational-Wave Observatory (LIGO) at the California Institute of Technology, now has a moment to catch his breath. But only a moment. Reitze said scientists are still analyzing data, but there will likely be no more announcements of ground-breaking discoveries while the LIGO detectors, which have already spotted merging black holes and colliding neutron stars, undergo modification.

Reitze said he believes the process of tweaking an interferometer is “more complex” than adjusting a big telescope. “With optical telescopes, as advanced as they are, there are a lot of tried-and-true things you can deal with. I think it’s easier to model the performance of an optical telescope than it is to model the performance of an interferometer. Which is not to give short-shrift to all the tremendous engineering challenges it takes to build a 30-meter optical telescope, to get the segments aligned to nanometer or sub-nanometer precision to get the image quality right. But there’s a lot of subtle stuff in interferometers that are a lot less understood.”

LIGO consists of two identical interferometers, located in Hanford, Washington, and Livingston, Louisiana. According to the LIGO website, “Each observatory consists of two long evacuated tunnels arranged in an L shape, at the joint of which a laser beam is split in two. Light is sent down the length of each tunnel, then reflected back in the direction it came from by a suspended mirror. In the absence of gravitational waves, the laser light in each tunnel should return to the location where the beams were split at precisely the same time. If a gravitational wave passes through the observatory, it will alter each laser beam’s arrival time, creating an almost imperceptible change in the observatory’s output signal.”

Once LIGO is back “on the air” in late 2018, Reitze said, “… we expect to be more sensitive by at least 30 percent, and that will have a disproportionate impact on the number of gravitational wave signals we see.” LIGO scientists expect to at least double the number of signals they’ve been receiving.

Reitze -- a 1996 Cottrell Scholar – was honored with The National Academy of Sciences (NAS) Award for Scientific Discovery along with Peter R. Saulson and Gabriela González. All three have held the post of elected spokesperson, effectively the leadership role, for the LIGO Scientific Collaboration (LSC) -- Saulson, 2003-2007; Reitze, 2007-2011; and González 2011-2016.  The award, endowed in 2014 in honor of John P. Schaefer, former president of Research Corporation for Science Advancement (RCSA), is presented every two years to recognize an accomplishment or discovery in basic research achieved within the previous five years. 

The successive efforts of the trio “paid off,” according to the NAS, “when the LSC announced that it had observed the gravitational waves from two colliding black holes, a collision that caused ripples in spacetime that could be measured on Earth. The observation, hailed as one of the most important scientific discoveries of 2015, proved the existence and properties of gravitational waves first predicted by Einstein in his General Theory of Relativity a century earlier and capped a 60-year experimental quest involving thousands of researchers from around the world. More importantly, the detection of gravitational waves passing through Earth on September 14, 2015, and then again on December 26, 2015, started a new field of gravitational wave astronomy.”

More recently, it was announced that on August 17 scientists associated with LIGO and its European counterpart, Virgo, situated near Pisa, Italy, directly detected gravitational waves as astronomers, moments later, were able to observe light from the spectacular collision of two neutron stars, marking the first time a cosmic event has been viewed in both gravitational waves and light, according to a LIGO press release.

Reitze’s two-decade journey from his initial Cottrell Scholar (CS) recognition to leadership of a highly successful “big science” project began at the University of Florida, where he was investigating ultrafast laser and spectroscopy processes in semiconductor quantum well structures as a path to developing quantum computers.

“It was a wonderful award,” he recalled. While the CS money brought much-needed research funding into his laboratory, he said the grant application process was memorable because it “forced me to think deeply, more deeply than I had ever thought in the past, about teaching science.”

About the time he received the CS Award, Reitze recalled, he also began looking into gravitational waves and LIGO, “but I continued to do what I was doing for the Cottrell Award until about 2006 or 2007. The longer term impact of the Cottrell Award was that it seeded a research project that later turned into quite a big program at the National High Magnetic Field Laboratory, a multimillion- dollar program to study coherent effects in semiconductors and using magnetic fields to actually keep them under control.”

By 2006, however, he was heavily involved in LIGO.

“At the time there were about 600 involved in the project,” Reitze recalled. (Today more than 1,200 scientists and engineers from 100 institutions around the world are involved in the Collaboration.) Over the next few years he more or less worked his way up the organizational ladder of the Collaboration, leading a group in charge of developing some of the key subsystems for both the LIGO and Advanced LIGO detectors. Subsequently, he led the Collaboration group that tackled how to make the best mirrors for the interferometers. Eventually he was elected spokesperson for the Collaboration.

“I learned that I brought to the table two things that scientists don’t always bring to the table, which was common sense and organizational skills,” he said.

As Collaboration spokesperson from 2007 to 2011, Reitze worked closely with Jay Marx, then executive director of the LIGO Laboratory at Caltech. “And I got to know him very well. We met on a weekly basis, and so I actually got to see inside – not all the details, but a good number of the ways the laboratory functioned, the ways it was able to carry out some of the really amazing feats of building this huge, complicated and remarkable detector.”

Marx eventually suggested that Reitze could be a viable candidate to succeed him if Reitze was interested in moving from a purely academic, professorial position to an administrative role.

“I decided this was a challenge, because it was a different kind of job; it comes with the idea of moving on, doing new things. But the other thing was that I knew everybody, I had become a colleague and in many cases friends with many of the people who are in the LIGO Laboratory right now, and I’d known them for 15 years or longer. I knew that they were extremely talented, and as a team they all worked together very well. They always put the global effort of getting LIGO operational ahead of their own specific parochial interests.”

There was a candidate search, but in the end Reitze was one of two finalists for the job.

He said he was selected in May 2011 because the committee valued his experience building some of the LIGO subsystems. “I don’t consider myself to be an expert in some of the things that are needed to make the interferometers work,” he said, “but I consider myself to be very versed in them. In making scientific decision you’re often forced to ask, well do we go in this direction, or do we go in that direction? And the committee thought I had a lot more background in the tech area that was going to be the thing that was going to be hard over the next five years.”

Reitze’s advice for the younger cohort among his fellow Cottrell Scholars is that, “Research is clearly important, and you have to make sure you dedicate the time and effort needed to be able to do that. Most tenure decisions, particularly at the research universities, are made primarily, not exclusively, but primarily on research and not education. But education is equally important, although in a different way. It’s important because the people you are educating are taxpayers. And taxpayers need to understand how science works, need to understand why it’s important, and need to realize there’s a huge benefit – societal, knowledge-wise, but also economic-wise, to doing fundamental research.”

He added that being a Cottrell Scholar has been a rewarding experience. “I haven’t done it lately, but I used to go to conference during the summer in Tucson, and those were great because you get a lot of excited young people together. It was very beneficial to my career.”

Given the dramatic decline in federal research funding over the past three decades, Reitze said he expects private science philanthropies like RCSA to play an increasing role in science advancement, although he’s well aware that currently philanthropies pick up about $2.3 billion of the nation’s research tab while the federal government supports about $23 billion.

Because private foundations are more flexible and quick to react than federal agencies, he suggested more private-government partnerships might be in order, such as a current one between the National Science Foundation and Gordon and Betty Moore Foundation.

“They came together to fund a critical problem in LIGO, which is making better optical coating for mirrors,” he said.  “Two-thirds of the funding came from NSF and a third came from the Moore Foundation. So these kinds of partnerships may be another way to address the funding problem.” 

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