Endnotes (+)

What Were the Most Memorable Sounds from Your Time at Caltech?

In our Summer 2015 issue, we asked alumni to share the campus sounds that most remind them of Caltech. We printed only a few of the responses we received. Here are several more, some of which were edited for grammar, spelling, length, and clarity.


¶ I am not sure about the other houses, but in Fleming, Handel’s Water Music usually accompanied someone being thrown into the shower.

¶ I grew up in southern New England, where everything was naturally green, and it was months before I realized that punctual daily predawn rainfall outside 209 Page was the sound of automatic sprinklers.

¶ For me it’s the high-pitched ding-ding-ding of a bell rung repeatedly. That always brings me right back to the Fleming dining hall.

¶ The sound, a sharp crack, of a baseball being struck with a well-swung bat; I was a pitcher on the baseball team for three years.

wake up700

¶ Back in the early ’50s, a string quartet gave a series of Dabney Hall concerts where they played all the Beethoven string quartets. I had never been exposed to chamber music before, but that started me off as a lifetime fan.

coca-cola-443123_1280_text350¶ Songs from the musical Camelot. I was the patch bay operator for the TACIT production (around 1990) and heard those songs sung many times during the rehearsals and shows.

¶ Waking up on the Blacker sleeping porch on California Boulevard and hearing the birds cough. (I actually wrote this to my folks freshman year—the smog was terrible!)

¶ Occasionally on Fridays at noon, there was a classical music performance in Dabney Hall, which had some of the most charming music that one could hear on campus. Those Fridays I would take my lunch with me to Dabney Garden and listen to the charming music played close by.


Preparing for Earthquakes with ShakeAlert (+)

In our Summer 2015 article “Everything Noise,” we looked at how vibrations of matter and energy can reveal crucial information about our world—at least when we’re able to tease a signal from the noise that often obscures it. We covered a related topic in our Summer 2013 issue, when we examined ways we could harness the earth’s vibrations to deliver early warnings of earthquakes through a system called ShakeAlert. We follow up on that story—“Can We Predict Earthquakes?”—here.

Screen Shot 2015-08-21 at 10.18.18 AMA few seconds may not seem like long, but it is enough time to turn off a stove, open an elevator door, or take cover under a desk. And before an earthquake strikes, a few seconds of warning can save lives. The U.S. Geological Survey aims to provide those seconds of warning with ShakeAlert, an earthquake early-warning system now being tested on the west coast of the United States. On July 30, the USGS announced approximately $4 million in awards to Caltech, UC Berkeley, the University of Washington, and the University of Oregon for the expansion and improvement of the ShakeAlert system.

“Caltech’s role in ShakeAlert will focus on research and development of the system so that future versions will be faster and more reliable,” says Thomas Heaton (PhD ’79, professor of engineering seismology and director of Caltech’s Earthquake Engineering Research Laboratory. “We currently collect data from approximately 400 seismic stations throughout California. The USGS grant will allow Caltech to upgrade or install new stations in strategic locations that will significantly improve the performance of ShakeAlert.”

Earthquakes radiate two kinds of seismic waves: fast-moving and often harmless P-waves, followed by S-waves, which can cause strong ground shaking. A system of seismometers called the California Integrated Seismic Network (CISN) acquires data streams literally at the speed of light and uses several algorithms to quickly pinpoint the earthquake’s epicenter and determine its strength. ShakeAlert analyzes the first P-waves in the CISN data streams to send out digital alerts, providing the “early warning” to a region before the slower, destructive S-waves arrive.

While predicting when and where an earthquake will occur is impossible, this early-warning system can provide valuable seconds to prepare for the jolt. Current beta-test users receive these alerts as a pop-up on their computers, displaying a map of the affected region, the amount of time until shaking begins, the estimated magnitude of the quake, and other data. In the future, alerts may be available through text messages and phone apps.

Though still technically in its testing stages, ShakeAlert has already provided successful warnings. In August 2014, the system provided a nine-second warning to the city of San Francisco during a magnitude 6.0 earthquake in South Napa. In May, during a magnitude 3.8 quake in Los Angeles, an alert was issued before S-waves had even reached the earth’s surface.

“With this new USGS funding, we will be able to add 20 new sensors to CISN, making coverage more robust and thus lengthening warning times,” says Egill Hauksson, a research professor of geophysics and a principal investigator along with Heaton on the ShakeAlert project. “Caltech and its partners will be able to continue the high-quality seismological research that is such a necessary foundation for a reliable earthquake early-warning system.”

In 2011, Caltech, along with UC Berkeley and the University of Washington, Seattle, received $6 million from the Gordon and Betty Moore Foundation for the research and development of ShakeAlert.

—Written by Lori Dajose


Begin at the Beginning

“ As this, the first issue of the Caltech Alumni Review goes to press we feel like the
frosh who has just purchased a bright new beanie and is trying it on in front of
his mirror. Admiring his reflection he is happy at the thought that he is now old
enough to be a college man and proud of his new colors—when the terrible thought
occurs to him that as soon as he steps from the privacy of his room he will be
laughed at, criticised, and paddled by the sophs, ignored by the upperclassmen.”

So began the “Foreword” of the enterprise that begat the E&S magazine in your hands—or on your computer screen or tablet or smart phone. Edited by Albert W. Atwood Jr., BS ‘32, and published by the Alumni Association of the California Institute of Technology, the very first issue of the Institute’s very first magazine—published in June of 1937—was not that very different from the E&S of today.

Click here to read the entire story.

Spiros Michalakis Tells an Unfinished Story (+)

Spiros Michalakis has little trouble finding an audience for his discussions of quantum mechanics. As we chronicled in the Random Walk article “Superhero Physics” in our Summer 2015 issue, Hollywood filmmakers actively sought his ideas for the movie Ant-Man.

Michalakis, the manager of outreach and a staff researcher at Caltech’s Institute for Quantum Information and Matter, also drew a crowd of science-loving students to his 2013 TEDxYouth@Caltech lecture, “Atoms—An Unfinished Story.”

The 11-minute lecture describes his quest—humorously framed as a lifelong bid to avenge a childhood chess-game drubbing—to build the ultimate quantum computer.

Everything Noise

“I like everything noise.”

Jonas Zmuidzinas’s new favorite saying is a phrase that’s been running through his mind a lot lately. A physicist at Caltech who develops instrumentation for use in astronomy, he spends an inordinate amount of his waking hours thinking about noise—but not in the way you might expect. For the average person, thinking about noise might mean trying to ignore the loud neighbors on a Sunday morning or using sound-cancelling headphones on a flight full of babies.

But for many scientists and engineers, a broader definition also assigns the term to the fluctuations in a measured signal that can obscure or reduce its clarity. “For people like myself who build instruments and detectors, noise is at the heart of what we do,” says Zmuidzinas. That’s because in engineering, for example, fluctuations, or noise, can arise from the random motions of atoms or electrons, and can manifest as heat or electronic static. And that can lead to malfunctioning machines. A clearer understanding of noise sources and ways to minimize it in circuits can lead to more efficient microchips and to telescopes that are capable of probing structures in the universe that were previously beyond reach.

Click here to read the full feature.

The Sounds of Science: Oceans, Rivers, and Glaciers

“My research literally includes the sound of waves crashing on the beach, the bubbling of a brook, and the crackling of glacial ice disintegrating as it flows into the ocean.”

Victor Tsai, assistant professor of geophysics, studies the seismic noise of ocean waves and rivers as well as glacier mechanics.



Fire and Ice: The Timing Was Nice (+)


This Landsat 8 image, acquired on September 6, 2014, is a false-color view of the Holuhraun lava field north of Vatnajökull glacier in Iceland. The image combines shortwave infrared, near infrared, and green light to distinguish between cooler ice and steam and hot extruded lava. The Bárðarbunga caldera, visible in the lower left of the image under the ice cap, experienced a large-scale collapse starting in mid-August.  Credit: USGS
This Landsat 8 image, acquired on September 6, 2014, is a false-color view of the Holuhraun lava field north of Vatnajökull glacier in Iceland. The image combines shortwave infrared, near infrared, and green light to distinguish between cooler ice and steam and hot extruded lava. The Bárðarbunga caldera, visible in the lower left of the image under the ice cap, experienced a large-scale collapse starting in mid-August.
Credit: USGS

The “Fire and Ice” Random Walk (see pages 4-5) item in our Summer 2015 issue highlighted a geological tour of Iceland by faculty members including Mark Simons, professor of geophysics. With limited space in the print magazine, we omitted mention of some fortuitous—from a scientific and educational standpoint—seismic events that happened to coincide with the excursion.

Along with Simons, fifteen students and two faculty members, landed in Reykjavik on August 16 of last year, for a tour of the volcanic, tectonic, and glaciological highlights of Iceland. That same day, a swarm of earthquakes began shaking the island nation—seismicity that was related to one of Iceland’s many volcanoes, Bárðarbunga caldera, which lies beneath Vatnajökull ice cap.

As the trip proceeded, it became clear to scientists studying the event that magma beneath the caldera was feeding a dyke, a vertical sheet of magma slicing through the crust in a northeasterly direction. On August 29, as the Caltech group departed Iceland, the dike triggered an eruption in a lava field called Holuhraun, about 40 kilometers (roughly 25 miles) from the caldera just beyond the northern limit of the ice cap.

Although the timing of the volcanic activity necessitated some shuffling of the trip’s activities, such as canceling planned overnight visits near what was soon to become the eruption zone, it was also scientifically fortuitous. Simons is one of the leaders of a Caltech/JPL project known as the Advanced Rapid Imaging and Analysis (ARIA) program, which aims to use a growing constellation of international imaging radar satellites that will improve situational awareness, and thus response, following natural disasters. Under the ARIA umbrella, Caltech and JPL/NASA had already formed a collaboration with the Italian Space Agency (ASI) to use its COSMO-SkyMed (CSK) constellation (consisting of four orbiting X-Band radar satellites) following such events.

Through the ASI/ARIA collaboration, the managers of CSK agreed to target the activity at Bárðarbunga for imaging using a technique called interferometric synthetic aperture radar (InSAR). As two CSK satellites flew over, separated by just one day, they bounced signals off the ground to create images of the surface of the glacier above the caldera. By comparing those two images in what is called an interferogram, the scientists could see how the glacier surface had moved during that intervening day. By the evening of August 28, Simons was able to pull up that first interferogram on his cell phone. It showed that the ice above the caldera was subsiding at a rate of 50 centimeters (more than a foot and a half) a day—a clear indication that the magma chamber below Bárðarbunga caldera was deflating.

The next morning, before his return flight to the United States, Simons took the data to researchers at the University of Iceland who were tracking Bárðarbunga’s activity.

“At that point, there had been no recognition that the caldera was collapsing. Naturally, they were focused on the dyke and all the earthquakes to the north,” says Simons. “Our goal was just to let them know about the activity at the caldera because we were really worried about the possibility of triggering a subglacial melt event that would generate a catastrophic flood.”

Luckily, that flood never happened, but the researchers at the University of Iceland did ramp up observations of the caldera with radar altimetry flights and installed a continuous GPS station on the ice overlying the center of the caldera.

Last December, Icelandic researchers published a paper in Nature about the Bárðarbunga event, largely focusing on the dyke and eruption. Now, completing the picture, Simons and his colleagues have developed a model to describe the collapsing caldera and the earthquakes produced by that action. The new findings appear in the journal Geophysical Journal International.

“Over a span of two months, there were more than 50 magnitude-5 earthquakes in this area. But they didn’t look like regular faulting—like shearing a crack,” says Simons. “Instead, the earthquakes looked like they resulted from movement inward along a vertical axis and horizontally outward in a radial direction—like an aluminum can when it’s being crushed.”

To try to determine what was actually generating the unusual earthquakes, Bryan Riel, a graduate student in Simons’s group and lead author on the paper, used the original one-day interferogram of the Bárðarbunga area along with four others collected by CSK in September and October. Most of those one-day pairs spanned at least one of the earthquakes, but in a couple of cases, they did not. That allowed Riel to isolate the effect of the earthquakes and determine that most of the subsidence of the ice was due to what is called aseismic activity—the kind that does not produce big earthquakes. Thus, Riel was able to show that the earthquakes were not the primary cause of the surface deformation inferred from the satellite radar data.

“What we know for sure is that the magma chamber was deflating as the magma was feeding the dyke going northward,” says Riel. “We have come up with two different models to explain what was actually generating the earthquakes.”

In the first scenario, because the magma chamber deflated, pressure from the overlying rock and ice caused the caldera to collapse, producing the unusual earthquakes. This mechanism has been observed in cases of collapsing mines (e.g., the Crandall Canyon Mine in Utah).

The second model hypothesizes that there is a ring fault arcing around a significant portion of the caldera. As the magma chamber deflated, the large block of rock above it dropped but periodically got stuck on portions of the ring fault. As the block became unstuck, it caused rapid slip on the curved fault, producing the unusual earthquakes.

“Because we had access to these satellite images as well as GPS data, we have been able to produce two potential interpretations for the collapse of a caldera—a rare event that occurs maybe once every 50 to 100 years,” says Simons. “To be able to see this documented as it’s happening is truly phenomenal.”

Additional authors on the paper, “The collapse of Bárðarbunga caldera, Iceland,” are Hiroo Kanamori, John E. and Hazel S. Smits Professor of Geophysics, Emeritus, at Caltech; Pietro Milillo of the University of Basilicata in Potenza, Italy; Paul Lundgren of JPL; and Sergey Samsonov of the Canada Centre for Mapping and Earth Observation. The work was supported by a NASA Earth and Space Science Fellowship and by the Caltech/JPL President’s and Director’s Fund.

Written by Kimm Fesenmaier

The Sounds of Science: LIGO

“We listen for changes in the separation of mirrors over the 4-kilometer length of each laser-interferometric detector. But thermal energy in the 0.4 millimeter diameter glass strings that hold up 40-kilogram mirrors also causes ringing sounds that we call ‘violin modes.’ And a hiss comes from the quantum nature of the light: fluctuations in the nothingness of empty space that interfere with our pure laser beam.”328-audio-icon

Rana Adhikari, professor of physics, talks about noises from the Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors. The aim of LIGO is to measure the stretching and squeezing of space-time. Scientists listen to the detector outputs—which are sometimes disturbed by things from the earth, such as earthquakes or traffic—using headphones.


Earlier this year, a scientific instrument dubbed SPIDER landed in a remote region of Antarctica. Conceived of and built by an international team of scientists, the instrument was launched on a balloon from McMurdo Station on New Year’s Day. Caltech and JPL designed, fabricated, and tested the six refracting telescopes the instrument used to map the thermal afterglow of the Big Bang, also known as the cosmic microwave background (CMB). SPIDER’s goal: to search the CMB for the signal of inflation, an explosive event that, in the first fraction of an instant after the birth of our universe, blew the observable cosmos up from a volume smaller than a single atom. The instrument appears to have performed well during its flight, says Jamie Bock, head of the SPIDER receiver team at Caltech and JPL. “Of course, we won’t know everything until we get the full data back as part of the instrument recovery.”

Photo of SPIDER afloat over Antarctica courtesy of SPIDER team

Take it to the Crowd

When you have a question about your health or your finances, you go to a doctor or an accountant for advice; you figure they have the knowledge you need to get the answers you’re looking for. But what about when you’re wondering where to go for dinner in a new city? Rather than hiring an expert chef to individually rate each restaurant—a pricey and time-consuming endeavor—you’d probably find it far more practical and efficient to trust the recommendations of the thousands of local diners who’ve already voluntarily rated the restaurants online.

Today, crowdsourcing—in which many individuals work toward the collective goal of narrowing down a large amount of information—has indeed made it easier to choose a good restaurant or pick a movie you’ll likely enjoy. But the concept has also found an application in areas of research where numerous scientists have collected far more data than they could ever analyze on their own.

By taking this data to the crowd, researchers at Caltech have found a way to engage the public while also allowing so-called citizen scientists to investigate a variety of research topics—from very tiny cells on Earth to massive star clusters in our galaxy.

Click here to read the full feature.

The Sounds of Science: Experiments in T5

“Experiments in T5, one of the GALCIT Hypersonics Group facilities, begin with a siren…to alert the building. Sometimes it’s mistaken for an earthquake warning. A few seconds later the tunnel fires, accelerating gas to the velocities required to simulate planetary entry flows. The gun shot-like sound and vibrations can be heard and felt through the building.”

Joanna Austin, professor of aerospace, uses pistons and explosives in large test tunnels to compress gases. She studies the mechanics involved in compressible flows, which come into play in problems ranging from the logistics of a spacecraft’s entry into a planet’s atmosphere to the hows and whys of volcanic eruptions.

Header photo by GALCIT

Good Vibrations

For their 1966 song, “Good Vibrations,” the Beach Boys assembled an unusual mix of instruments—including a jaw harp, a cello, and an Electro-Theremin—to produce one of their biggest hits. By arranging sound waves in a unique and particular way, they were able to elicit a positive response.

Many doctors and researchers have the same goal. After all, the same “excitations” that helped the Beach Boys usher in an era of feel-good pop—the sound waves that propagate through air and water, bringing notes of music to our ears—are also noninvasively able to explore body tissues, helping to visualize babies in the womb, heal back pain, or even deliver chemotherapeutics to targeted tumors.

Click here to read the full feature…