JPL News: Versatile Instrument to Scout for Kuiper Belt Objects

At the Palomar Observatory near San Diego, astronomers are busy tinkering with a high-tech instrument that could discover a variety of objects both far from Earth and closer to home.

The Caltech HIgh-speed Multi-color camERA (CHIMERA) system is looking for objects in the Kuiper Belt, the band of icy bodies beyond the orbit of Neptune that includes Pluto. It can also detect near-Earth asteroids and exotic forms of stars. Scientists at Caltech and NASA's Jet Propulsion Laboratory are collaborating on this instrument.

"The Kuiper Belt is a pristine remnant of the formation of our solar system," said Gregg Hallinan, CHIMERA principal investigator at Caltech. "By studying it, we can learn a large amount about how our solar system formed and how it's continuing to evolve."

"Each of CHIMERA's cameras will be taking 40 frames per second, allowing us to measure the distinct diffraction pattern in the wavelengths of light to which they are sensitive," said Leon Harding, CHIMERA instrument scientist at JPL. "This high-speed imaging technique will enable us to find new Kuiper Belt objects far less massive in size than any other ground-based survey to date."

Hallinan's CHIMERA team at Caltech and JPL published a paper led by Harding describing the instrument this week in the Monthly Notices of the Royal Astronomical Society.

Read the full story from JPL News

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The CHIMERA system is looking for objects in the Kuiper Belt, the band of icy bodies beyond the orbit of Neptune that includes Pluto.

LIGO Panel Peers into New Window on the Universe

On September 14, 2015, the twin Laser Interferometry Gravitational-wave Observatory (LIGO) detectors sensed the infinitesimal vibrations of a black hole merger that took place over one billion years ago. This discovery, announced worldwide on February 11, 2016, has opened a new window on the universe. On February 23, Caltech held a public event to discuss the discovery of gravitational waves and what it will mean for our ongoing exploration and understanding of the universe.

A panel of scientists from Caltech and LIGO—moderated by Fiona Harrison, the Benjamin M. Rosen Professor of Physics and the Kent and Joyce Kresa Leadership Chair of the Division of Physics, Mathematics and Astronomy—gave a series of short talks describing their experiences with the project.

Opening remarks were delivered by President Thomas Rosenbaum, who described the discovery of gravitational waves as a "connecting of heaven and earth," likening it to the 18th-century image of lightning striking a key on a kite string. He commended the extraordinary four-decade-long vision of the project and said that it demonstrated how the combination of people and technology could change the world.

According to panelist Kip Thorne, the Richard P. Feynman Professor of Theoretical Physics, Emeritus, who has been working on the search for gravitational waves since the 1960s, and who detailed for the audience the setup of the identical detectors (located in Hanford, Washington, and Livingston, Louisiana), "Caltech's support for this project has never faltered since the beginning," he said. "It's very impressive."

"This is the biggest project the National Science Foundation has ever taken on," noted Barry Barish, the Ronald and Maxine Linde Professor of Physics, Emeritus, who described the history of building the detectors and the plans to improve their sensitivities. The NSF, he said, "never wavered, even in this high-risk endeavor. What we have just done in detecting gravitational waves is not the end of the story."

In their talks, Professor of Physics Rana Adhikari, and Anamaria Effler (BS '06), a postdoctoral scholar at the LIGO Livingston Observatory, described the painstaking effort needed to achieve and maintain the sensitivities of the LIGO detectors—which, after the Advanced LIGO technical upgrade, became the most precise measuring instrument ever constructed. Adhikari discussed the steps to limit Earth's own gravitational noise, the material science behind the superreflective mirrors used in the detectors, and the "squeezed-light system" used to minimize quantum-mechanical noise. Effler talked about the challenge of reducing environmental noise—from earthquakes, oceanic storms, planes, lightning storms, and even air-conditioning units. "Detecting a gravitational wave is like trying to hear someone at the back of a room scratch their nose, while everyone else in the room is screaming," she said.

Stan Whitcomb, LIGO chief scientist, described plans to add more detectors around the globe—including a LIGO detector in India—enabling scientists to more accurately locate the sources of gravitational waves. Whitcomb also expressed the need for accurate predictions of the gravitational-wave signals that would be produced by other cosmic phenomena—such as the mergers of neutron stars, which are extremely dense stars—in order to recognize them when they happen.

Mansi Kasliwal, an assistant professor of astronomy, described future efforts to characterize such events that produce gravitational waves. "There should be an immense flash of light, when these events occur. We use telescopes around the world to look at the sky for these flashes, and narrow down which one could have produced the gravitational waves," said Kasliwal, whose group has already successfully identified sources of gamma-ray bursts with this method.

Several of the panelists described their reactions shortly after the September 14 detection.

Mike Landry, the lead scientist at the LIGO Hanford Observatory, described how he felt upon coming into the lab the morning of the detection, and his surprise upon learning that the signal was not a test. "Often we do tests on our detectors, called blind injections, where we simulate a gravitational-wave event," he said. "I raced into the lab and asked if we were in a blind injection phase—and to my everlasting amazement, I was told no."

"I don't know if you know the feeling," said panelist Alan Weinstein, professor of physics. "You spend 15 years working on something and then suddenly there it is staring at you in the face." (Adhikari noted that it took "easily a month" before he was convinced the detection was real.)

Weinstein, who described gravitational waves as the sound of the vibrations of spacetime itself, noted that LIGO had ended the "silence" of astronomy. "It's going to be a very loud future," agreed Whitcomb.

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LIGO Panel - Our New Window on the Universe
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Scientists reflect on the history, the detection, the science, and the future of the field of gravitational wave astronomy.

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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Caltech Asteroid Hunter Gives TED Talk
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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 Gets Green Light
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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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New Public Stargazing and Lecture Series
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The events are free and designed to engage the public in astronomy and to give everyone an opportunity to look through a telescope.
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]

[Watch the recorded lecture]

THE TITLE
 

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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