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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Considering the Future
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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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LIGO's Beginnings
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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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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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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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Contemplating a Quantum Future

Last week, Caltech's Institute for Quantum Information and Matter (IQIM) honored the legacy and contributions of theoretical physicist Richard Feynman, marking 50 years since he received the Nobel Prize in Physics for his work on quantum electrodynamics. Feynman spent much of his career working to understand better the laws and implications of quantum mechanics—the rules that dictate the bizarre behavior of matter at the scale of individual atoms and particles. He foresaw how quantum mechanics could lead to the development of nanotechnology and even a quantum computer that could solve problems that would be intractable for conventional computers. Over two days, IQIM hosted two events to celebrate that vision by exploring the research and development currently underway at what might be called the quantum frontier.

The first event, "One Entangled Evening," aimed to delight, educate, and inspire an audience not only of scientists and engineers but also of artists, entertainers, and members of the public. Among the highlights of the evening were a video tribute to Feynman by Microsoft cofounder Bill Gates; a song and dance about quantum mechanics performed by artist Gia Mora and John Preskill, the Richard P. Feynman Professor of Theoretical Physics at Caltech and director of IQIM; and a screening of a short video titled Anyone Can Quantum, narrated by actor Keanu Reeves and featuring actor Paul Rudd playing a game of "quantum chess" with renowned physicist Stephen Hawking.

The following day, IQIM hosted an all-day Quantum Summit that brought together scientists and engineers from academia and industry to discuss progress in the quantum realm.

One session featured a panel discussion about the future of quantum computers with researchers from Google, HP Laboratories, IBM, Intel, the Institute for Quantum Computing, and Microsoft. Moderated by Jennifer Ouellette, senior science editor at Gizmodo.com, the discussion started with brief descriptions of the approach that each company or institute is taking in the quest for a quantum computer as well as answers to the questions, "Why quantum computing, and why now?"

Ray Beausoleil leads the Large-Scale Integrated Photonics research group at HP Laboratories. His team is currently trying to put thousands of nonlinear optical devices on a chip and to get them interacting coherently—in a way that their quantum properties are not disturbed by outside noise. As for his answer to the "Why quantum now?" question, "If you're a big computer company, you're looking at quantum computing because you know that, depending on your point of view … Moore's Law is in danger of being over," he explained. "So we have to start thinking more energetically about what computing will look like in 10 to 20 years."

"People have been saying that Moore's Law was over since about the time Richard Feynman proposed the quantum computer," countered Jim Clarke, manager of quantum hardware and novel memory research at Intel. Intel was cofounded by Gordon Moore (PhD '54), the originator of Moore's Law—the 1965 prediction that the amount of processing power, based on the number of transistors in a circuit, will double about every two years. "My take is Moore's Law is not ending," Clarke continued. "In fact, I think we need at least a couple more generations of Moore's Law just to be able to enable a large-scale quantum computer."

IBM Fellow Charles Bennett said that IBM is working to get a small number of superconducting qubits to work coherently and to understand what those qubits are doing. "That is a tremendous task, and we're putting a lot of effort into that," he said.

Parsa Bonderson, a theoretical physicist from Microsoft's Station Q at UC Santa Barbara, said that while Microsoft is keeping its eyes on a number of approaches, its main focus is on topological quantum computing, an idea devised in the 1990s by Alexei Kitaev, now the Ronald and Maxine Linde Professor of Theoretical Physics and Mathematics at Caltech. The approach attempts to develop much more stable qubits, known as topological qubits, that would be less sensitive to the disturbances that destroy the quantum properties of all other qubits. (Jason Alicea, professor of theoretical physics at Caltech, provided an overview of topological quantum computing in an earlier session at the summit.)

And why now? Bonderson answered, "We're starting to really feel like this could be within reach this time."

Google, for one, seems to agree. The company made headlines in 2013 when it bought a system from D-Wave Systems, a startup company that has built an early prototype of a limited quantum computer. Google's main goal, noted its director of engineering Hartmut Neven, is "to get a practical quantum computer as quickly as we can."

What can be done with a quantum computer? Krysta Svore, a senior researcher in Microsoft's Quantum Architectures and Computation Group, works to address that question and presented a number of potential answers in a morning session at the summit. Some of the ideas that reach beyond improving scientists' ability to study quantum systems include improving machine learning and simulating chemicals and chemical reactions more precisely in order to facilitate drug design and improving machine learning.

Ouellette asked the panelists what they thought might be possible with a small quantum computer, perhaps with 100 qubits.

Ray Laflamme, executive director of the Institute for Quantum Computing at the University of Waterloo, in Ontario, said he would use such a computer to help train students, postdocs, and young faculty "to think quantumly."

Intel's Clarke spoke about modeling the dynamics of molecules, including ozone and carbon dioxide, which are just out of reach of conventional computers. "Well, that's climate change, so that resonates with a lot of people," he said. "If you go even further, you get into the protein space. … Misfolded proteins are the genesis of so many diseases—cancer, multiple sclerosis, and others."

Microsoft's Bonderson suggested that a small quantum computer might be useful for designing a better quantum computer. And Bennett reminded everyone that the quantum computer would likely do more than simply provide more processing power. "It's not going to be the solution to the supposed problem of the demise of Moore's Law. It's going to change things in a way that is more interesting," he said. "It's like saying if we've got radio, how much better does that make things than if we just had the telegraph or we just had post offices?"

Beausoleil added that he would not let himself try to determine how the quantum computer should be used. Instead, he said, "I'd put it online as rapidly as possible and let people who are not physicists start experimenting."

And Google's Neven talked about the potential applications of a full-fledged quantum computer in the artificial intelligence (AI) field. Noting that formulating fundamental laws of physics is extremely difficult and something that only a tiny fraction of people can do, he said, "The question is: Is this really a task that, as physics develops further, remains a human task? Or is this, rather, a task that we should hand over to machines?"

He said that he believed that forms of artificial intelligence could prove to be better physicists and that quantum computing would be involved. "I would dare to conjecture that the most creative systems we will ever see will be quantum AI systems," he said.

During other sessions at the summit, John Martinis of Google spoke about quantum simulation with superconducting qubits; Oskar Painter, the John G. Braun Professor of Applied Physics at Caltech, presented on acoustic quantum transducers; and David Wineland, a Nobel laureate from National Institute of Standards and Technology, described the latest thinking on entangled trapped ions.

IQIM, which spans Caltech's Divisions of Physics, Mathematics and Astronomy and Engineering and Applied Science, is a Physics Frontiers Center supported by the National Science Foundation and by the Gordon and Betty Moore Foundation. 

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Contemplating a Quantum Future
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IQIM hosted a Quantum Summit that brought scientists and engineers together to discuss progress in the quantum realm.

Bock Receives Award for Astronomical Instrumentation

Jamie Bock, professor of physics and Jet Propulsion Laboratory senior research scientist, has received the Joseph Weber Award for Astronomical Instrumentation from the American Astronomical Society (AAS). The award citation notes his "development of low-noise 'spider-web' bolometers"—devices for measuring radiation—that have enabled fundamental measurements of the cosmic microwave background. The award is given annually for the design, invention, or significant improvement of instrumentation leading to advances in astronomy.

The spider-web bolometers, developed to detect millimeter-wave and far-infrared radiation, enabled a generation of ground-based and balloon-borne experiments for mapping variations in the cosmic microwave background, or CMB, which is thermal radiation from the early universe. The most notable of the telescopes employing these bolometers,, the BOOMERanG balloon experiment, made measurements of the CMB that ultimately determined that the overall geometry of the universe is very nearly flat. Detector arrays later flew on the Planck spacecraft and provided what is currently the ultimate measurement of the CMB over the full sky, and flew as well on the Herschel Space Observatory, a 3.5-meter space-based telescope for far-infrared astronomy. Modern descendants of the spider-web bolometers are actively engaged in measuring CMB polarization from Earth's South Pole.

After receiving his PhD in physics from UC Berkeley in 1994, Bock joined JPL as a research scientist and Caltech as a visiting associate. He was named a senior research scientist and full professor in 2012.

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Jamie Bock has received the Joseph Weber Award for Astronomical Instrumentation.

JPL News: Uranus as seen by NASA's Voyager 2

Humanity has visited Uranus only once, and that was 30 years ago. NASA's Voyager 2 spacecraft got its closest look at the mysterious, distant, gaseous planet on January 24, 1986.

Voyager 2 sent back stunning images of the planet and its moons during the flyby, which allowed for about 5.5 hours of close study. The spacecraft got within 50,600 miles (81,500 kilometers) of Uranus during that time.

"We knew Uranus would be different because it's tipped on its side, and we expected surprises," said Voyager mission project scientist Ed Stone, who is also Caltech's David Morrisroe Professor of Physics and vice provost for special projects. Stone has served as project scientist since 1972, continuing in that role today.

Read the full story from JPL News

 

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Friday, January 29, 2016
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Hopkins Receives Honors from American Astronomical Society

Assistant Professor of Theoretical Astrophysics Philip Hopkins has received the Helen B. Warner Prize for Astronomy from the American Astronomical Society (AAS) for his research in galaxy formation and evolution, and the growth of massive black holes. The award is given annually for significant contributions to observational or theoretical astronomy during the five years preceding the award.

"It is an incredible honor to be awarded the Warner prize," Hopkins says. "The previous winners are a prestigious company, including many of my own idols and mentors in astrophysics, and it is amazing to be listed among these giants in our field."

Hopkins studies the formation of astronomical objects like galaxies, stars, and supermassive black holes. Leading the Feedback in Realistic Environments (FIRE) project, he and his group aim to synthesize theoretical models and observations, and bring together experts on these different phenomena to understand how they interact.

"After stars form, they aren't just 'done,'" Hopkins says. "They do important things like exploding as supernovae—and the energy released in these explosions can throw around interstellar matter and actually launch winds out of galaxies that carry away most of the matter which would otherwise have formed more stars."

Hopkins and his group have shown that these so-called feedback loops between stars, black holes, and galaxies are crucial to understanding the masses and structures of galaxies. The AAS award citation describes Hopkins as a "world expert in stellar feedback" and his work as giving "great insight into the role of galaxy mergers on galaxy properties as well as quasar activation."

"At a profound level, we have realized that seemingly diverse populations in our universe—quasars, starbursts, ultraluminous galaxies, 'red and dead' galaxies, galaxy mergers, star clusters, planets, and more—are all tightly connected to one another in a constantly interacting ecosystem," he says.

Previous recipients of the award include Professor of Theoretical Astrophysics and Executive Officer for Astronomy Sterl Phinney (BS '80), and Shri Kulkarni, the John D. and Catherine T. MacArthur Professor of Astronomy and Planetary Science.

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