Caltech Names Six Distinguished Alumni

Caltech has announced that Eric Betzig (BS '83), Janet C. Campagna (MS '85), Neil Gehrels (PhD '82), Carl V. Larson (BS '52), Thomas J. "Tim" Litle IV (BS '62), and Ellen D. Williams (PhD '82) are this year's recipients of the Distinguished Alumni Award.

First presented in 1966, the award is the highest honor the Institute bestows upon its graduates. It is awarded in recognition of a particular achievement of noteworthy value, a series of such achievements, or a career of noteworthy accomplishment. Presentation of the awards will be given on Saturday, May 21, 2016, as part of Caltech's Seminar Day.

The 2016 Distinguished Alumni Award recipients are

Eric Betzig (BS '83, Physics)

Physicist; Group Leader, Janelia Research Campus, Howard Hughes Medical Institute

Betzig is being recognized for his groundbreaking contributions to microscopy. He pioneered a method known as single-molecule microscopy, or "nanoscopy," which allows cellular structures at the nanoscale to be observed using optical microscopy. For the work, he shared the Nobel Prize in Chemistry in 2014.

Janet C. Campagna (MS '85, Social Science)

CEO, QS Investors

Campagna is being recognized for her contributions to quantitative investment and for her leadership in the financial industry. Campagna is the founder of QS Investors, LLC, a leading customized solutions and global quantitative equities provider. She is responsible for all business, strategic, and investment decisions within QS Investors. 

Neil Gehrels (PhD '82, Physics)

Chief of the Astroparticle Physics Laboratory, NASA's Goddard Space Flight Center

Gehrels is being recognized for his scientific leadership in the study of gamma ray bursts as well as for his significant contributions to high-energy astrophysics, infrared astronomy, and instrument development.

Carl V. Larson (BS '52, Mechanical Engineering)

Larson is being recognized for his accomplished career in the electronics industry. Over the course of three decades, Larson has held numerous and diverse leadership roles in fields ranging from engineering to marketing. He is also being celebrated for his sustained commitment to the research, students, and alumni of Caltech.

Thomas J. "Tim" Litle IV  (BS '62, Engineering and Applied Science)

Founder and Chairman, Litle & Co.

Litle is being recognized for his revolutionary contributions to commerce. Through innovations such as the presorted mail program he developed for the U.S. Postal Service and the three-digit security codes on credit cards, Litle has made global business more efficient and secure.

Ellen D. Williams (PhD '82, Chemistry)

Director, Advanced Research Projects Agency-Energy (ARPA-E)

Williams is being recognized for her sustained record of innovation and achievement in the area of structural surface physics. She founded the Materials Research Science and Engineering Center at the University of Maryland and was the chief scientist for BP. She now serves as director of the Advanced Research Project Agency (ARPA-E) in the U.S. Department of Energy.

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The awardees range from the class of 1952 to the class of 1983, across a wide range of divisions.

Caltech Asteroid Hunter Gives TED Talk

Caltech staff scientist Carrie Nugent, who discovers and characterizes asteroids utilizing data from the NASA NEOWISE (Near-Earth Object Wide-field Infrared Survey Explorer) program, presented her research as one of the selected speakers at the 2016 TED Conference this week in Vancouver, British Columbia. The semiannual conference showcases ideas representing a broad range of disciplines, from science to literature to philosophy.

"It's very exciting," says Nugent, who works in the Infrared Processing and Analysis Center. "NEOWISE is funded by taxpayer money, and it's so important that people understand what their money is doing. With a TED talk, I get to reach a huge and unique audience."

NEOWISE is an infrared telescope that takes photos of space every 11 seconds. Originally designed to look beyond the solar system, it is now in an extended-mission phase in which it is searching for and characterizing asteroids within our solar system. Because asteroids are remnants from the formation of the early solar system, the data gathered by NEOWISE may provide insights into the conditions and chemistry of the protoplanetary environment.

One major goal of NEOWISE is to determine the size of asteroids, notes Nugent. "It seems like such a basic thing to determine, but really, only one in five asteroids has a measured size," she says. "If we are just looking at the light reflected from an asteroid, then it could either be very small and very shiny, or very large and very dim—the light reflected would be the same. But by using NEOWISE, we can detect the amount of heat emitted by an object, which gives you a sense of its size."

Nugent, who has been working with asteroids since graduate school, says there is still much to learn about these small celestial bodies.

"Every planet has been visited by a probe at least once, but we haven't even discovered most asteroids," she says. "It is literally uncharted territory. By characterizing their orbits and measuring their sizes, we are building an archive that will last."

Discovering asteroids comes with perks—like getting to name them. Some of Nugent's discoveries include 284996 Rosaparks, named for civil rights activist Rosa Parks, and 241528 Tubman, named for abolitionist Harriet Tubman.

The TED conference was not Nugent's first experience with public outreach—in her spare time, she runs a podcast called Spacepod, in which she interviews scientists and engineers, including many at Caltech and JPL, about their research.

The 2016 TED conference was focused on "the greatest dreams we are capable of dreaming," and was held February 15–19.

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Carrie Nugent spoke at the 2016 TED conference about her work discovering, naming, and characterizing asteroids.

LIGO-India Gets Green Light

Following this month's announcement of the first observation of gravitational waves arriving at the earth from a cataclysmic event in the distant universe, the Indian Cabinet, chaired by Prime Minister Shri Narendra Modi, has granted in-principle approval to the Laser Interferometer Gravitational-wave Observatory in India (LIGO-India) Project. The project will build an Advanced LIGO Observatory in India, a move that will significantly improve the ability of scientists to pinpoint the sources of gravitational waves and analyze the signals. Approval was granted on February 17, 2016.

Gravitational waves—ripples in the fabric of space and time produced by dramatic events in the universe, such as merging black holes, and predicted as a consequence of Albert Einstein's 1915 general theory of relativity—carry information about their origins and about the nature of gravity that cannot otherwise be obtained. With their first direct detection, announced on February 11, scientists opened a new window onto the cosmos.

The twin LIGO Observatories at Hanford, Washington, and Livingston, Louisiana, are funded by the U.S. National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. Advanced LIGO—a major upgrade to the sensitivity of the instruments compared to the first generation LIGO detectors—began scientific operations in September 2015. Funded in large part by the NSF, Advanced LIGO enabled a large increase in the volume of the universe probed, leading to the discovery of gravitational waves during its first observation run.

At each observatory, the two-and-a-half-mile (4-km) long L-shaped interferometer uses laser light split into two beams that travel back and forth down the arms (four-foot diameter tubes kept under a near-perfect vacuum). The beams are used to monitor the distance between mirrors precisely positioned at the ends of the arms. According to Einstein's theory, the distance between the mirrors will change by an infinitesimal amount when a gravitational wave passes by the detector. A change in the lengths of the arms smaller than one-ten-thousandth the diameter of a proton (10-19 meter) can be detected.

According to David Reitze, executive director of LIGO and a Caltech research professor, the degree of precision achieved by Advanced LIGO is analogous to being able to measure the distance between our solar system and the sun's nearest neighbor Alpha Centauri—about 4.4 light-years away—accurately to within a few microns, a tiny fraction of the diameter of a human hair.

"We have built an exact copy of that instrument that can be used in the LIGO-India Observatory," says David Shoemaker, leader of the Advanced LIGO Project and director of the MIT LIGO Lab, "ensuring that the new detector can both quickly come up to speed and match the U.S. detector performance."

LIGO will provide Indian researchers with the components and training to build and run the new Advanced LIGO detector, which will then be operated by the Indian team.

According to a statement from the Indian Cabinet, "LIGO-India will also bring considerable opportunities in cutting edge technology for the Indian industry," which will be responsible for the construction of the new observatory's 4-kilometer-long beam tubes. In addition, the Cabinet statement says, "The project will motivate Indian students and young scientists to explore newer frontiers of knowledge, and will add further impetus to scientific research in the country."

The Indian effort brings together three of the country's top research institutes; the Inter-University Centre for Astronomy and Astrophysics (IUCAA), the Raja Ramanna Centre for Advanced Technology (RRCAT), and the Institute for Plasma Research (IPR). The project is managed by the Department of Atomic Energy and the Department of Science and Technology.

"It is technically feasible for LIGO-India to go online by the end of 2023," says Fred Raab, head of the LIGO Hanford Observatory and LIGO Laboratory liaison for LIGO-India. LIGO scientists have made dozens of trips to India to work with Indian colleagues, especially with the three nodal institutes that would have primary responsibility for construction and operation of LIGO India: IPR Gandhinagar, RRCAT Indore, and IUCAA Pune. "Together, we have identified an excellent site for the facilities and have transferred detailed LIGO drawings of the facilities and vacuum system to IPR, after adapting them for conditions in India," he says.

Scientists at RRCAT have designed a special testing/prototype facility for receiving Advanced LIGO parts; have been training the teams that will install and commission the detector; and are currently cross-checking the IPR vacuum-system drawings against the Advanced LIGO detector drawings, to ensure a good fit and rapid installation for the third Advanced LIGO detector. In addition to leading the site-selection process, IUCAA scientists have been setting up a computing center for current and future data. This preparation should make it possible for India to carry the project forward rapidly.

"LIGO-India will further expand the international network that started with the partnership between LIGO and Virgo, which operates a detector near Pisa, Italy," says Stanley Whitcomb, LIGO chief scientist. "With LIGO-India added to the network, we will not only detect more sources, we will dramatically increase the number of sources that can be pinpointed so that they can be studied using other types of telescopes." That ability is pivotal because combining both gravitational-wave and light-based astronomy enables a much more robust understanding of an observed object's characteristics—in much the same way that lightning is better comprehended through sight and hearing than sight alone.

"The game to see the light from these catastrophic mergers is on," says Mansi Kasliwal, assistant professor of astronomy and the leader of the Caltech effort to search for electromagnetic emission from gravitational waves using the intermediate Palomar Transient Factory, a robotic survey for astrophysical transients (brief, intense flashes of light), and a network of other telescopes. "LIGO India is out of the plane of the other three advanced gravitational-wave interferometers. Thus, it will help narrow down the on-sky location of the gravitational waves tremendously and give a big boost to the astronomers hunting for the light."

Indian astronomers have a long tradition of work in general relativity, gravitational waves, the development of algorithms for gravitational wave detection, and also in the data analysis itself, notes Ajit Kembhavi, emeritus professor at IUCAA Pune and chair of the LIGO-India site-selection committee. "The LIGO-India project provides a great opportunity to take these interests forward and to participate in the rapid development of the field, which may very well come to dominate astronomy for some time," he says.

"LIGO-India will be able to attract young people with a variety of skills from the numerous students who are engaged in strong programs in STEM education," adds Somak Raychaudhury, director of IUCAA Pune.

Fleming Crim, assistant director for mathematical and physical sciences at NSF, praised the expansion of the project, saying, "Because the science reward is so strong, NSF enthusiastically endorses the decision of the Indian government to proceed with authorizing funding for the LIGO-India project."

Gabriela González, a professor of physics at Louisiana State University and spokesperson for the LIGO Scientific Collaboration (LSC), says LIGO will "enable us to answer fundamental questions about the universe that no other type of astrophysics or astronomy can answer." The LSC consists of more than 1000 scientists from more than 90 institutions worldwide, including a large group of researchers in India

The project may also reveal answers to questions no one has yet thought to ask. Notes Reitze: "Any time you turn on some new type of telescope or microscope, you discover things you couldn't anticipate. So while there will be certain sources of gravitational waves that we expect to see, the really exciting part is what we did not predict and what we did not expect to see."

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LIGO-India, a third Advanced LIGO Observatory, will improve scientists' ability to pinpoint the sources of gravitational waves and analyze the signals.

Astronomy Hosts New Public Stargazing and Lecture Series

Caltech's astronomy department is kicking off a new stargazing and lecture series with the first installment taking place this Friday, February 19, at 7 p.m. in Hameetman Auditorium on campus. The monthly events will be free and open to the public and are designed to appeal to scientists and nonscientists alike. Following a 30-minute lecture on an astronomical topic, attendees will have an opportunity to observe the night sky through a telescope with the help of Caltech students and researchers.

The organizer of the new public education series is Cameron Hummels, a National Science Foundation Postdoctoral Fellow in astrophysics. In his research, Hummels develops computer simulations that model the evolution of galaxies. His hydrodynamical gravitational simulations begin with the very early universe—just a few million years after the Big Bang—and run forward, incorporating gravity and the dynamics of gas to try to reproduce the kinds of galaxies we see in the universe today. The results can be used to better understand astronomical observations and to answer fundamental questions about how galaxies form and evolve.

Hummels has long believed in the importance of public astronomy programs. He has clear memories of his father taking him out one night—he thinks he was in the second grade—to a sidewalk astronomy event in the parking lot of a school near his house. The experience of looking through a telescope for the first time to see Saturn and a star cluster left an indelible impression on him that eventually led him toward a career in astrophysics. "It was really exciting," he says. "And what we're going to be doing is very similar."

Hummels arrived at Caltech last fall, having just completed another postdoctoral fellowship at the University of Arizona. Prior to that, he was a graduate student at Columbia University in New York City, where he and another graduate student, Neil Zimmerman, became directors of the astronomy outreach program, which at the time hosted only a couple of small events each year. With unreliable weather and the city's significant light pollution often hampering planned observing events, Hummels and Zimmerman quickly realized that their programs needed to include another component—an event that would happen regardless of observing conditions. They added a lecture component, inviting fellow students and faculty members to give talks on their research. The events were a hit. Within a couple of years, the semimonthly events were drawing crowds of 150 to 250 people—the capacity of their venue.

Here at Caltech, Hummels is applying the same basic model. For the inaugural event on Friday, Evan Kirby, an assistant professor of astronomy at Caltech, will present a brief lecture titled "An Archaeological Road Trip with the Keck Telescopes" at 7 p.m. Immediately afterward, if the weather and viewing conditions permit, astronomers will help attendees observe interesting features of the night sky through telescopes on the north athletics field. There will also be an informal Q&A panel on gravitational waves inside following the lecture.

"It's fun for everybody," Hummels says. "Almost everyone has the experience of marveling at the night sky, whether it's from a scientific bent or a philosophical curiosity. As a researcher, I really enjoy it because as excited as you might be about your own topic, the slog of dealing with it day after day can grind you down. Going to these events is reinvigorating because it causes you to rediscover your field a bit."

In addition to the stargazing and lecture series, Hummels is also coordinating a sidewalk astronomy program that will involve Caltech astronomers setting up telescopes on Colorado Boulevard and encouraging passersby to take a look at the heavens. He set up a similar program at Columbia, on Harlem's 125th Street, and says the response was overwhelming. "It was so rewarding because a lot of the people walking down the street had never looked through a telescope before, and some of them were blown away by the experience," he says. "When you do that sort of thing, you are really reaching out to people who may be totally ambivalent toward science."

For Hummels, public education is what lies at the heart of his outreach efforts. "Having an educated populace is super important," he says. "I think it's extremely important that we, as scientists who are largely funded by publicly funded agencies, give back to the community. And I think astronomy lends itself very well as a tool for engaging the public in science education—plus it's entertainment!"

Hameetman Auditorium is located in the Cahill Center for Astronomy and Astrophysics at 1216 E. California Blvd. Stargazing will only be possible if the skies are clear. You can check the Astronomy Outreach page on the day of the event for weather status. No reservations are necessary to attend.

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Monday, February 29, 2016

Modeling molecules at the microscale

Considering the Future

Science and Society conference to honor Nobel Laureate Ahmed Zewail

Can we find life on other planets? Can we bridge the economic divide between rich and poor? Can we engineer the human body to live longer than our genes currently allow, and should we even attempt such a thing?

On February 26, some of the nation's leading scientists and researchers—including five Nobel laureates, two of whom are from Caltech—will gather at Caltech to discuss some of the most perplexing questions facing humanity. During a one-day conference titled "Science and Society," they will address an eclectic mix of topics ranging from current efforts to reduce global poverty to the mechanical workings of clocks so accurate that they lose less than a second every 300 million years.

The conference has been organized in honor of Ahmed Zewail, Caltech's Linus Pauling Professor of Chemistry and professor of physics, who was the sole recipient of the 1999 Nobel Prize in Chemistry for his development of the field of femtochemistry. Zewail, who also serves as director of Caltech's Physical Biology Center for Ultrafast Science and Technology, has lived the concept that science should drive the betterment of society, not only in his academic life, but in his advocacy as a U.S. science envoy to the Middle East and scientific advisor to the United Nations, and as a leader within his native Egypt, as exemplified by the role he played both during and after the Egyptian revolution of 2011.

"Science plays a vital role in helping people live better lives and helping humanity understand its place in the universe, and it's a rare treat for so many distinguished people to gather in one place to discuss these fascinating topics," says Zewail. "The theme that will shine through in this conference is that a passion for science, combined with a sense of optimism, can make the almost-impossible possible."

The conference, which will be held in Beckman Auditorium, will include speakers from Caltech, Stanford, the University of Maryland, and the Jet Propulsion Laboratory. Caltech's president, Thomas F. Rosenbaum, and provost, Edward Stolper, as well as Jacqueline Barton, chair of the Division of Chemistry and Chemical Engineering, and Fiona Harrison, the Kent and Joyce Kresa Leadership Chair of the Division of Physics, Mathematics and Astronomy, will open the conference; Rosenbaum will also provide concluding remarks at the end of the day.

The other speakers will include Caltech Nobel laureate David Baltimore, who will talk about "The Future of Medicine" and the CRISPR technology that is now teaching scientists how to "edit" a person's genes, an undertaking that raises a host of ethical questions. "Since medicine has brought us from a life expectancy of 45 years to one of 77 in the last century, it is reasonable to expect medicine will be able to extend it to 85 or even 100," says Baltimore, the Robert Andrews Millikan Professor of Biology. "But to go much beyond that, we would need to think about altering our genes. Should we think about that?"

William Phillips, a physicist at the National Institute of Standards and Technology and a Nobel laureate, will give a talk titled "Time, Einstein, and the Coolest Stuff in the Universe." His discussion will focus on how scientists are using supercold atoms to "allow tests of some of Einstein's strangest predictions" and to create supremely accurate atomic clocks, which, he says, "are essential to industry, commerce, and science." Phillips is also a Distinguished University Professor at the University of Maryland, College Park.

JPL director Charles Elachi will predict—in his talk about "The Future of Space Exploration"—that, during the next decade, we will establish permanent scientific stations on Mars and engage in a search for present or past ocean life on the moons of Europa, Enceladus, and Titan. Elachi believes that, in the near future, "we will also be imaging and characterizing planets around neighboring stars to see if we are alone."

Roger Kornberg, Nobel laureate and the Mrs. George A. Winzer Professor in Medicine at the Stanford School of Medicine, will discuss "The End of Disease." His talk will look at the challenges faced by the scientific community from both "biomedical and political myopia," while also considering the capacity and power of physics, chemistry, and biology to bring modern medicine forward.

A. Michael Spence, a Nobel laureate from the Stanford Graduate School of Business who will speak on "Inequality and World Economics," believes the integration of the world economy has helped reduce global income inequality on a "massive scale." Nonetheless, he says, the economic divide between rich and poor is getting larger within many countries, including virtually all developed nations. In his lecture, Spence says, he will try "to unpack the contributing factors to this inequality, its results, and how to respond effectively to this trend."

And Caltech's H. Jeff Kimble, the William L. Valentine Professor and professor of physics, will be focusing on "startling advances in quantum physics"—specifically, how the complex correlations that arise among many strongly interacting quantum objects has and can continue to shape computation, communication, and the health of physics and society more generally. 

Visit the Science and Society Conference website for more information about the event and to register and receive updates.

Written by Alex Roth

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On February 26, some of the nation's leading scientists and researchers will gather at Caltech to discuss some of the most perplexing questions facing humanity.

LIGO's Beginnings

Built to look for gravitational waves, the ripples in the fabric of space itself that were predicted by Einstein in 1916, the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced the detection of gravitational waves—generated during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole—on February 11, 2016.

LIGO, the most ambitious project ever funded by the National Science Foundation, consists of two L-shaped interferometers with four-kilometer-long arms; at their ends hang mirrors whose motions are measured to within one-thousandth the diameter of a proton. Managed jointly by Caltech and MIT, Initial LIGO became operational in 2001; the second-generation Advanced LIGO was dedicated on May 19, 2015. On September 14 at 2:51 a.m. Pacific Daylight Time, both of the twin LIGO detectors, located in Livingston, Louisiana, and Hanford, Washington, nearly simultaneously detected the characteristic "chirp" of the black holes' fusion.

Barry Barish, Caltech's Ronald and Maxine Linde Professor of Physics, Emeritus, was LIGO's principal investigator from 1994 to 1997, and director from 1997 to 2006. Stan Whitcomb (BS '73) was an assistant professor of physics at Caltech from 1980 to 1985. He returned to campus as a member of the professional staff in 1991 and has served the LIGO project in various capacities ever since. We talked with each of them about how LIGO came to be.

How did LIGO get started?

BARISH: Einstein didn't think that gravitational waves could ever be detected, because gravity is such a weak force. But in the 1960s, Joseph Weber at the University of Maryland turned a metric ton of aluminum into a bar 153 centimeters long. The bar naturally rang at a frequency of about 1,000 hertz. A collapsing supernova should produce gravitational waves in that frequency range, so if such a wave passed through the bar, the bar's resonance might amplify it enough to be measurable. It was a neat idea, and basically initiated the field experimentally. But you can only make a bar so big, and the signal you see depends on the size of the detector.

[Professor of Physics, Emeritus] Ron Drever, whom we recruited from the University of Glasgow, had started out working on bar detectors. But when we hired him, he and Rainer [Rai] Weiss at MIT were independently developing interferometer-type detectors—a concept previously suggested by others. Usually you fasten an interferometer's mirrors down tightly, so that they keep their alignment, but LIGO's mirrors have to be free to swing so that the gravitational waves can move them. It's very difficult to do incredibly precise measurements with big, heavy masses that want to move around.

WHITCOMB: Although bar detectors were by far the most sensitive technology at the time, it appeared that they would have a much harder path reaching the sensitivity they would ultimately need. Kip Thorne [BS '62, Richard P. Feynman Professor of Theoretical Physics, Emeritus] was really instrumental in getting Caltech to jump into interferometer technology and to try to bring that along.

Ron's group at Glasgow had built a 10-meter interferometer, which was all the space they had. We built a 40-meter version largely based on their designs, but trying to improve them where possible. In those days we were working with argon-ion lasers, which were the best available, but very cantankerous. Their cooling water introduced a lot of vibrational noise into the system, making it difficult to reach the sensitivity we needed. We were also developing the control systems, which in those days had to be done with analog electronics. And we had some of the first "supermirrors," which were actually military technology that we were able to get released for scientific use. The longer the interferometer's arms, the more sensitive it can be for gravitational waves. We bounce the light back and forth hundreds of times, essentially making the interferometer several thousand kilometers long.

When did the formal collaboration with MIT begin?

BARISH: Rai [Weiss] and Ron [Drever] were running their own projects at MIT and Caltech, respectively, until [R. Stanton Avery Distinguished Service Professor and Professor of Physics, Emeritus] Robbie Vogt, Caltech's provost, brought them together. They had very different ways of approaching the world, but Robbie somehow pulled what was needed out of both of them.

Robbie spearheaded the proposal that was submitted to the National Science Foundation in 1989. That two-volume, nearly 300-page document contained the underpinnings—the key ideas, technologies, and concepts that we use in LIGO today. A lot of details are different, a lot of features have been invented, but basically even the dimensions are much the same.

WHITCOMB: When I returned in 1991, LIGO had become a joint Caltech-MIT project with a single director, Robbie Vogt. Robbie had brought in a set of engineers, many borrowed or recruited from JPL, to do the designs. The late Boude Moore [BS '48, MS '49], our vacuum engineer, was figuring out how to make LIGO's high-vacuum systems out of low-hydrogen-outgassing stainless steel. This had never been done before. Hydrogen atoms absorbed in the metal slowly leak out over the life of the system, but our measurements are so precise that stray atoms passing through the laser beams would ruin the data. Boude was doing some relatively large-scale tests, mostly in the synchrotron building, but we also built a test cylinder 80 meters long near Caltech's football field, behind the gym.

So all of these tests were going on piecemeal at different places, and at the 40-meter interferometer we brought it all together. We were still mostly using analog electronics, but we had a new vacuum system, we redid all the suspension systems, we added several new features to the detector, and we had attained the sensitivity we were going to need for the full-sized, four-kilometer LIGO detectors.

And at the same time, in 1991, we got word that the full-scale project had been approved.

How were the sites in Hanford, Washington, and Livingston, Louisiana, selected?

WHITCOMB: I cochaired the site-evaluation committee with LIGO's chief engineer, [Member of the Professional Staff] Bill Althouse. We visited most of the potential sites, evaluated them, and recommended a set of best site pairs to NSF. We had several sets of criteria. The engineering criteria included how level the site was, how stable it was against things like frost heaves, how much road would need to be built, and the overall cost of construction. We had criteria about proximity to people, and to noise sources like airports and railroads. We also had scientific criteria. For example, we wanted the two sites to be as far apart in the U.S. as you could reasonably get. We also wanted LIGO to work well with either of the two proposed European detectors—GEO600 [in Hanover, Germany] and Virgo [in Tuscany, Italy]. We needed to be able to triangulate a source's position on the sky, so we did not want LIGO's sites to form a line with either of them.

What makes Advanced LIGO more sensitive?

BARISH: Well, it's complicated. Most very sensitive physics experiments are limited by some source of background, so the task of the experimentalist is to concentrate on the limiting background and figure out how to beat it down. But LIGO has three different limiting backgrounds. We are looking for gravitational waves over a very wide range of frequencies from 10 hertz to 10 kilohertz. Our planet is incredibly noisy seismically at low frequencies, and consequently from 10 hertz to about 100 hertz we have to isolate ourselves from that shaking. As we move up to frequencies in the middle range, we are limited by what we call "thermal noise"—the atoms in the mirrors moving around, and, at the very high frequencies, we have to sample the signal faster and faster, and we become limited by the laser's power or the number of photons we can sample in a short amount of time. This is called "shot noise."

Advanced LIGO has significantly reduce our backgrounds from all three sources using a very much more powerful laser to take care of the high frequencies, a much fancier isolation system including active feedback systems for low frequencies, and larger test masses with better mirror coatings to minimize the thermal background. Such improvements were conceived from the beginning, and consequently our strategy was to build Initial LIGO with proven techniques that had mostly been tested here on campus in the 40-meter prototype; followed by Advanced LIGO, using techniques yet to be developed and tested in our laboratories after Initial LIGO was operational. Now, we are developing and testing the next round of upgrades in our laboratory.

What is your reaction to the first detection?

BARISH: It is fantastic! I've always had the fond wish that we would succeed by 2016, which is the hundredth anniversary of Einstein's prediction of gravitational waves. It will take three to five more years for Advanced LIGO to reach the designed sensitivity, but we are taking science data along the way, while we improve the sensitivity. The first step improved the sensitivity by about a factor of three better than initial LIGO, and that turned out to be enough to make the first detection. The sensitivity tells you how far out you can see, and volume increases with the cube of the distance. A factor of three is a very big step, and that enabled our first detection.

This first detection is every bit as exciting as we could have hoped for, or maybe even more. We have directly detected gravitational waves one hundred years after Einstein's prediction, and if that isn't enough, the detection itself is proving important astrophysically—it is the first detection of such a binary black hole system—and further, the event is enabling important fundamental physics through important tests of general relativity.

This is just the start, not the end. We now can confidently look forward to a very bright future as we open up this new field, using gravitational waves as both a totally new probe to observe our universe, as well as a new means of studying the fundamental physics of general relativity.

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The Laser Interferometer Gravitational-Wave Observatory (LIGO) is the most ambitious project ever funded by the National Science Foundation.

Chasing Extrasolar Space Weather

Earth's magnetic field acts like a giant shield, protecting the planet from bursts of harmful charged solar particles that could strip away the atmosphere. Gregg Hallinan, an assistant professor of astronomy, aims to detect this kind of space weather on other stars to determine whether planets around these stars are also protected by their own magnetic fields and how that impacts planetary habitability.

On Wednesday, February 10, at 8 p.m. in Beckman Auditorium, Hallinan will discuss his group's efforts to detect intense radio emissions from stars and their effects on any nearby planets. Admission is free.

[Watch the recorded lecture]

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What do you do?

I am an astronomer. My primary focus is the study of the magnetic fields of stars, planets, and brown dwarfs—which are kind of an intermediate object between a planet and a star.

Stars and their planets have intertwined relationships. Our sun, for example, produces coronal mass ejections, or CMEs, which are bubbles of hot plasma explosively ejected from the sun out into the solar system. Radiation and particles from these solar events bombard the earth and interact with the atmosphere, dominating the local "space weather" in the environment of Earth. Happily, our planet's magnetic field shields and redirects CMEs toward the polar regions. This causes auroras—the colorful light in the sky commonly known as the Northern or Southern Lights.

Our new telescope, the Owens Valley Long Wavelength Array, images the entire sky instantaneously and allows us to monitor extrasolar space weather on thousands of nearby stellar systems. When a star produces a CME, it also emits a bright burst of radio waves with a specific signature. If a planet has a magnetic field and it is hit by one of these CMEs, it will also become brighter in radio waves. Those radio signatures are very specific and allow you to measure very precisely the strength of the planet's magnetic field. I am interested in detecting radio waves from exoplanets—planets outside of our solar system—in order to learn more about what governs whether or not a planet has a magnetic field.

Why is this important?

The presence of a magnetic field on a planet can tell us a lot. Like on our own planet, magnetic fields are an important line of defense against the solar wind, particularly explosive CMEs, which can strip a planet of its atmosphere. Mars is a good example of this. Because it didn't have a magnetic field shielding it from the sun's solar wind, it was stripped of its atmosphere long ago. So, determining whether a planet has a magnetic field is important in order to determine which planets could possibly have atmospheres and thus could possibly host life.

How did you get into this line of work?

From a young age, I was obsessed with astronomy—it's all I cared for. My parents got me a telescope when I was 7 or 8, and from then on, that was it.

As a grad student, I was looking at magnetic fields of cool—meaning low-temperature—objects. When I was looking at brown dwarfs, I found that they behave like planets in that they also have auroras. I had the idea that auroras could be the avenue to examine the magnetic fields of other planets. So brown dwarfs were my gateway into exoplanets.

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Chasing Extrasolar Space Weather
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Hunting for Ephemeral Cosmic Flashes: A Conversation with Mansi Kasliwal

Mansi Kasliwal (PhD '11), a new assistant professor of astronomy, searches the night sky for astrophysical transients—flashes of light that appear when stars become a million to a billion times as bright as our sun and then quickly fade away. She and her colleagues have developed robotic surveys to help detect these transient events, and she has built a global network of collaborators and telescopes aimed at capturing details of the flashes at all wavelengths.

Kasliwal grew up in Indore, India, and came to the United States to study at the age of 15. She earned her BS at Cornell University and then came to Caltech to complete her doctoral work in astronomy. She completed a postdoctoral fellowship at the Carnegie Observatories in Pasadena before returning to Caltech as a faculty member in September.

We sat down with Kasliwal to discuss her passion for discovering and studying these cosmic transients as well as her recent efforts to follow up on LIGO's detections of gravitational waves.

What do you actually see when you discover a cosmic transient?

You see a flash of light on the screen and then you see it disappear—often it's gone in a few days or even a few hours. In that short time, you try to get at the chemistry of the event. You try to take the light from the flash and disperse it; once you get a spectrum, you can tell what sorts of elements it's actually made of.

So, I search for these cosmic transients, try to understand what they are all about, and look for new types of them.

What types of events produce these flashes?

The most common varieties of these flashes are novae and supernovae. Novae are produced by nuclear explosions on stellar remnants called white dwarfs, while core-collapse supernovae are related to the deaths of massive stars. Novae are about a million times the brightness of the sun, and supernovae are a billion times as bright. For a long time we didn't know of anything in between, but today we know of many classes of transients with luminosities between novae and supernovae that involve mergers between these crazy objects. That's where a lot of the most interesting stellar physics happens—when something like a white dwarf smashes into a neutron star or a neutron star smashes into a black hole.

These are extreme events, and it turns out that a lot of the chemical elements that we see around us are synthesized in these explosions. For example, when I was doing my PhD thesis here, I found a rare class of events that generates about half of the calcium in the universe. For decades, people had wondered where all the calcium was made because there was much more of it around than supernovae alone could synthesize. We found this group of very rare explosions. We call them calcium-rich gap transients because they appear to be the mines in the universe where calcium is made.

Are they exploding stars?

We actually don't know. Our best guess is that they are some sort of white dwarf–neutron star merger. We now have a sample of about eight of these events and have been able to quantify the calcium made in each, showing that even though these events are rare, each one produces so much calcium that, as a class, they can account for the missing calcium.

On what does your research currently focus?

Right now I'm looking for the cosmic mines of the heavy elements. If you look at the periodic table, about half of the elements heavier than iron—things like gold, platinum, and uranium—are produced by something called r-process nucleosynthesis. We know these elements are produced by this process, but astronomers still don't know where this process takes place. We've never seen it in action. None of the explosions that we've found so far has been extreme enough to actually synthesize enough heavy elements.

What types of events might produce these heavy elements?

Theoretically, we expect that the most extreme events involve a neutron star merging with a black hole or with another neutron star—because neutron stars and black holes are much denser than white dwarfs, for example. But these explosions are extremely rare. They happen maybe once per 10,000 years per galaxy. By comparison, novae are easy to find because there are about 20 of those per year per galaxy. Supernovae are harder, but they still happen about once per century per galaxy.

To look for these rarer and more exotic events, you need the next generation of surveys and telescopes. Your response needs to be quick. The flash of light happens very rarely, it lasts for a very short time, and it's dim. So you have the worst of all worlds when you're trying to find them.  

To overcome this challenge, we are working in close collaboration with Advanced LIGO (the Laser Interferometer Gravitational-Wave Observatory with enhanced detectors to try to detect ripples in the fabric of space-time caused by such extreme events). The idea is that Advanced LIGO will "hear" the gravitational sound waves, and our surveys at Palomar Observatory, currently the intermediate Palomar Transient Factory (PTF), and eventually the Zwicky Transient Facility (ZTF), will see the light from the binary neutron-star merger.

Were you involved in efforts to follow up on Advanced LIGO's recent detection of gravitational waves? What did you see?

I am leading the Caltech effort to look for electromagnetic counterparts to gravitational waves. PTF responded automatically and promptly to the gravitational wave alerts from LIGO and imaged hundreds of square degrees of the localization that was accessible from Palomar Observatory. Within minutes, we reduced our data, and within hours we orchestrated a global follow-up campaign for our most promising candidates—the brightest flashes that could have possibly correlated with the LIGO detection. We obtained spectroscopic follow-up of our candidates from the Keck and Gemini observatories, radio follow-up from the Very Large Array, and X-ray follow-up from the Swift satellite. None of our candidates was related to the gravitational wave trigger, which is what you would expect for a merger of two black holes.

Finding the electromagnetic counterpart to a merger between two neutron stars or a neutron star and a black hole could identify the cosmic mines of heavy elements such as gold and platinum. It is very exciting that this much-awaited gold rush has actually begun!

Can you talk more about PTF and ZTF and also address how you first became interested in this field?

When I came to grad school and took my first course, the known explosions were of two types: novae and supernovae. I thought, "Nature's more creative than that."

For my PhD thesis, we came up with a plan-A, a plan-B, and a plan-C for how to search for events in between, and the Palomar Transient Factory (PTF) was plan-D.

For PTF, we roboticized a couple of telescopes at Palomar Observatory and imaged huge swaths of sky over and over again, looking for things that changed. Because we were imaging such a large area at such a rapid rate, we actually began finding these very rare flashes of light.

Now we're working hard on ZTF, which should come online in 2017. It is an order of magnitude more sensitive than PTF and hence poised to uncover rarer events. Instead of a seven-square-degree camera, we have a 47-square-degree camera; instead of taking 40 seconds to read out the camera, it will take less than 15 seconds.

Are you working on other projects?

I am leading a couple of projects. The first is a project called SPIRITS, which stands for the SPitzer InfraRed Intensive Transients Survey. We are looking for infrared transients. Although there are many surveys at optical wavelengths, the infrared is completely pristine. It's like going off fishing in new waters.

We use the Spitzer Space Telescope and a bunch of ground-based observatories to take images in the infrared of 242 nearby galaxies on different timescales. Most of what I'm finding so far seems to be mergers of individual massive stars and the births of binaries, which you can only see in the infrared because they form in a red cloud of gas and dust.

This is a Spitzer Exploration Science Program, which means we've been granted more than 1,300 hours of time on the space telescope to do this in a very big way over three years.

And the other project?

I'm also the principal investigator on the GROWTH (Global Relay of Observatories Watching Transients Happen) project that was recently funded by the National Science Foundation's Partnerships in International Research and Education program. Our network includes six U.S. universities and six foreign countries spanning the globe to observe transients before they fade away, beating sunrise.

In building this network, we went both for telescopes that would make sense for the network and for people who would enjoy this type of science. It is not for everyone. It's nerve-wracking—you're doing work at 2 a.m., 3 a.m., and if you drop the ball, it's a pretty big deal. We tried to pick coinvestigators who are sufficiently excited about the science so that when they wake up, they aren't in a grumpy mood.

Outside of your research, are you passionate about any other activities?

There is a wonderful organization called Asha, which means hope, which runs schools for underprivileged children in India. To me education is the solution to many of the problems in India. I've been helping Asha with fundraising and setting up these schools. When I go back home, I try to visit the Asha schools. When you meet the children and see that they are actually getting an education and have dreams … it feels good. It's small, but it matters. 

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Kimm Fesenmaier
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Hunting for Ephemeral Cosmic Flashes
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An interview with Mansi Kasliwal, a new assistant professor of astronomy, who studies astrophysical transients.

Gravitational Waves Detected 100 Years After Einstein’s Prediction

LIGO opens new window on the universe with observation of gravitational waves from colliding black holes

For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein's 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.

Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed.

The gravitational waves were detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (09:51 UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. The discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.

Based on the observed signals, LIGO scientists estimate that the black holes for this event were about 29 and 36 times the mass of the sun, and the event took place 1.3 billion years ago. About 3 times the mass of the sun was converted into gravitational waves in a fraction of a second—with a peak power output about 50 times that of the whole visible universe. By looking at the time of arrival of the signals—the detector in Livingston recorded the event 7 milliseconds before the detector in Hanford—scientists can say that the source was located in the Southern Hemisphere.

According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes. During the final fraction of a second, the two black holes collide into each other at nearly one-half the speed of light and form a single more massive black hole, converting a portion of the combined black holes' mass to energy, according to Einstein's formula E=mc2. This energy is emitted as a final strong burst of gravitational waves. It is these gravitational waves that LIGO has observed.

LIGO was originally proposed as a means of detecting these gravitational waves in the 1980s by Rainer Weiss, professor of physics, emeritus, from MIT; Kip Thorne, Caltech's Richard P. Feynman Professor of Theoretical Physics, emeritus; and Ronald Drever, professor of physics, emeritus, also from Caltech.

"With this discovery, we humans are embarking on a marvelous new quest: the quest to explore the warped side of the universe—objects and phenomena that are made from warped spacetime. Colliding black holes and gravitational waves are our first beautiful examples," says Thorne.

 "The description of this observation is beautifully described in the Einstein theory of general relativity formulated 100 years ago and comprises the first test of the theory in strong gravitation. It would have been wonderful to watch Einstein's face had we been able to tell him," says Weiss.

"Caltech thrives on posing fundamental questions and inventing new instruments to answer them," says Caltech president Thomas Rosenbaum, the Sonja and William Davidow Presidential Chair and professor of physics. "LIGO represents an exhilarating example of how this approach can transform our knowledge of the universe. We are proud to partner with NSF and MIT and our other scientific collaborators to lead this decades-long effort."

"Our observation of gravitational waves accomplishes an ambitious goal set out over five decades ago to directly detect this elusive phenomenon and better understand the universe, and, fittingly, fulfills Einstein's legacy on the 100th anniversary of his general theory of relativity," says Caltech's David H. Reitze, executive director of the LIGO Laboratory.

"This discovery is just the beginning," says Fiona Harrison, the Benjamin M. Rosen Professor of Physics and holder of the Kent and Joyce Kresa Leadership Chair of the Division of Physics, Mathematics and Astronomy. "Over the next years, LIGO will be putting general relativity to its most stringent tests ever, it will be discovering new sources of gravitational waves, and we will be using telescopes on the ground and in space to search for light emitted by these catastrophic events."

The existence of gravitational waves was first demonstrated in the 1970s and 80s by Joseph Taylor, Jr., and colleagues. Taylor and Russell Hulse discovered in 1974 a binary system composed of a pulsar in orbit around a neutron star. Taylor and Joel M. Weisberg in 1982 found that the orbit of the pulsar was slowly shrinking over time because of the release of energy in the form of gravitational waves. For discovering the pulsar and showing that it would make possible this particular gravitational wave measurement, Hulse and Taylor were awarded the Nobel Prize in Physics in 1993.

The new LIGO discovery is the first observation of gravitational waves themselves, made by measuring the tiny disturbances the waves make to space and time as they pass through the earth.

LIGO research is carried out by the LIGO Scientific Collaboration (LSC), a group of more than 1000 scientists from universities around the United States and in 14 other countries. More than 90 universities and research institutes in the LSC develop detector technology and analyze data; approximately 250 students are strong contributing members of the collaboration. The LSC detector network includes the LIGO interferometers and the GEO600 detector. The GEO team includes scientists at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI), Leibniz Universität Hannover, along with partners at the University of Glasgow, Cardiff University, the University of Birmingham, other universities in the United Kingdom, and the University of the Balearic Islands in Spain.

"This detection is the beginning of a new era: The field of gravitational wave astronomy is now a reality," says Gabriela González, LSC spokesperson and professor of physics and astronomy at Louisiana State University.

The discovery was made possible by the enhanced capabilities of Advanced LIGO, a major upgrade that increases the sensitivity of the instruments compared to the first generation LIGO detectors, enabling a large increase in the volume of the universe probed—and the discovery of gravitational waves during its first observation run. The US National Science Foundation leads in financial support for Advanced LIGO. Funding organizations in Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council, STFC) and Australia (Australian Research Council) also have made significant commitments to the project. Several of the key technologies that made Advanced LIGO so much more sensitive have been developed and tested by the German UK GEO collaboration. Significant computer resources have been contributed by the AEI Hannover Atlas Cluster, the LIGO Laboratory, Syracuse University, and the University of Wisconsin-Milwaukee. Several universities designed, built, and tested key components for Advanced LIGO: The Australian National University, the University of Adelaide, the University of Florida, Stanford University, Columbia University of New York, and Louisiana State University.

"In 1992, when LIGO's initial funding was approved, it represented the biggest investment the NSF had ever made," says France Córdova, NSF director. "It was a big risk. But the National Science Foundation is the agency that takes these kinds of risks. We support fundamental science and engineering at a point in the road to discovery where that path is anything but clear. We fund trailblazers. It's why the U.S. continues to be a global leader in advancing knowledge."

"The Advanced LIGO detectors are a tour de force of science and technology, made possible by a truly exceptional international team of technicians, engineers, and scientists," says David Shoemaker of MIT, the project leader for Advanced LIGO. "We are very proud that we finished this NSF-funded project on time and on budget, and delighted Advanced LIGO delivered its groundbreaking detection so quickly."

At each observatory, the two-and-a-half-mile (4-km) long L-shaped LIGO interferometer uses laser light split into two beams that travel back and forth down the arms (four-foot diameter tubes kept under a near-perfect vacuum). The beams are used to monitor the distance between mirrors precisely positioned at the ends of the arms. According to Einstein's theory, the distance between the mirrors will change by an infinitesimal amount when a gravitational wave passes by the detector. A change in the lengths of the arms smaller than one-ten-thousandth the diameter of a proton (10-19 meter) can be detected.

Independent and widely separated observatories are necessary to determine the direction of the event causing the gravitational waves, and also to verify that the signals come from space and are not from some other local phenomenon.

A network of detectors will significantly help to localize the sources. The Virgo detector will be the first to join later this year.

The LIGO Laboratory also is working closely with scientists in India at the Inter-University Centre for Astronomy and Astrophysics, the Raja Ramanna Centre for Advanced Technology, and the Institute for Plasma to establish a third Advanced LIGO detector on the Indian subcontinent. Awaiting approval by the government of India, it could be operational early in the next decade. The additional detector will greatly improve the ability of the global detector network to localize gravitational-wave sources.

Virgo research is carried out by the Virgo Collaboration, consisting of more than 250 physicists and engineers belonging to 19 different European research groups: 6 from Centre National de la Recherche Scientifique (CNRS) in France; 8 from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; 2 in The Netherlands with Nikhef; the Wigner RCP in Hungary; the POLGRAW group in Poland, and the European Gravitational Observatory (EGO), the laboratory hosting the Virgo detector near Pisa in Italy.

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Einstein's Prediction Confirmed by LIGO
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