Einstein's Cosmic Symphony
SU physicists are part of an international team of scientists listening to the universe
Editor's Note: This story originally appeared in Syracuse University Magazine.
Somewhere in the vast expanses of the universe, two spinning black holes are locked in a death spiral, pulled together by gravity. They collide. The violent confrontation produces ripples—gravitational waves, which herald news of the event at the speed of light across space and time. These are Einstein’s Messengers.
Albert Einstein predicted the existence of gravitational waves in 1916 in his theory of general relativity; it took more than 80 years for scientists to invent ways to detect them. Like radio waves, which need to be decoded and amplified by a radio before music can be heard, gravitational waves need to be decoded by instruments that can distinguish the music from the noise. Scientists believe this cosmic music is encoded with information about the celestial bodies—colliding black holes, neutron stars, and exploding stars—that generate the waves, as well as with clues that may reveal the fundamental nature of gravity, and perhaps, the origin of the universe.
Scientists in Syracuse University's College of Arts and Sciences are among a select group of gravitational-wave researchers in the country who are leading efforts to decode Einstein’s symphony. The SU group is part of a worldwide coalition of scientists called the Laser Interferometer Gravitational Wave Observatory Scientific Collaboration, or LIGO as it’s known. In partnership with the National Science Foundation (NSF), the consortium—led by the Massachusetts Institute of Technology (MIT) and the California Institute of Technology (Caltech)—built facilities in Hanford, Washington, and Livingston, Louisiana, to search for the elusive waves. Commissioned in 2001, the LIGO observatories were operational until October 2010, when the instruments were dismantled to make way for Advanced LIGO, the next generation of the project. The observatories are expected to be fully operational again in 2015.
Through its participation in the LIGO Scientific Collaboration, the SU group has garnered almost $8 million in NSF funding for the University since 1991. That’s when Peter Saulson arrived at SU and established one of the first, NSF-funded, LIGO-related research labs outside of Caltech and MIT. Saulson, the Martin A. Pomerantz ’37 Professor of Physics in the College of Arts and Sciences, trained under the best. Fresh out of Princeton with a newly minted Ph.D., he went to MIT in 1981 and spent eight years working with Rainer Weiss, a giant in the gravitational-wave field who developed the concept for LIGO’s core technology—the laser interferometer, a device designed to detect gravitational waves passing across Earth on their cosmic journey. “It was an act of intellectual courage for the College of Arts and Sciences to hire me,” Saulson says. “There had been no history of NSF funding for LIGO outside the core groups.” Saulson was the lead scientist for the LIGO Livingston Observatory in 2000, ensuring the instrument was constructed properly and performed well, and served as the scientific spokesperson for the LIGO collaboration between 2003 and 2007. In addition, Saulson did early research at SU that played a key role in improving the glass mirrors—key components in the interferometer—that will be installed in Advanced LIGO.
Building a LIGO Supercomputer
Five years ago, Professor Duncan Brown joined the physics department. As a graduate student at the University of Wisconsin-Milwaukee (UW-M), Brown wrote a major piece of the gravitational-wave search software used by LIGO. He subsequently spent three years working with Caltech’s Kip Thorne who, alongside Weiss, is a key player in gravitational-wave research and in the LIGO collaboration. Brown, an NSF CAREER award recipient and Cottrell Scholar, was the principal investigator in a project to build a LIGO supercomputer at SU. Funded by the NSF and The College of Arts and Sciences, the cluster is housed in the new Green Data Center on South Campus. Collaborating on the project were co-principal investigators Tomasz Skwarnicki, professor of physics; and Christopher Sedore, associate vice chancellor for academic operations. The SU supercomputer is one of three LIGO computing centers that join with the LIGO Laboratory's main computing center to provide resources for LIGO scientists worldwide. The other two are located at UW-M and the Albert Einstein Institute for Gravitational Physics in Germany.
The SU group is also taking the lead on projects to improve the gravitational-wave search software for Advanced LIGO (see related story: Clangs and Bangs) and develop new technologies that will increase the sensitivity of LIGO instruments beyond what is currently possible. In addition to Saulson and Brown, the group includes physics professor Stefan Ballmer, who is building a mini-LIGO prototype at SU to explore new ways to enhance the sensitivity of LIGO instruments (see related story: Squeezing Light). Computing specialist Peter Couvares, two postdoctoral researchers, seven graduate students, and two undergraduates are also involved in SU’s LIGO research group.
About Mirrors and 'Jiggle'
At the core of LIGO technology is the laser interferometer, which uses a beam of light and a photodetector to sense gravitational waves. Specifically, it measures the distance light travels in a vacuum between suspended mirrors located at either end of four-kilometer-long, L-shaped “arms.” Gravitational waves and other vibrations and noise cause the mirrors to move a tiny bit—less than the diameter of a proton. The movement changes the distance light travels between the mirrors, which is measured by the photodetector and converted into an electrical signal—the musical notes of the cosmos.
One noise that plagued the initial LIGO instruments was a barely perceptible jitter in the glass mirrors caused by friction from the movement of silicon and oxygen atoms in the glass. The jitter was invisible to the naked eye—and most instruments—but loud enough to cover the sound of gravitational waves. “We needed to significantly reduce this noise, but the only trick we knew was to replace the glass with sapphire, which has very low friction,” Saulson says. “I spent my first 10 years at SU trying to learn whether there was any way you could buy, treat, or hold a form of glass that would have the friction level of sapphire yet retain the properties we required—and we found it.”
Saulson’s team discovered an extremely pure form of silicon dioxide that has a very low internal friction. It was a significant accomplishment that required the team to develop a way to measure internal friction before they could begin to analyze different types of glass. Saulson has now moved to new areas of LIGO research, one of which is to improve the gravitational-wave search software for Advanced LIGO. “As cool as the glass stuff is, I really want to find gravitational waves in the data,” Saulson says. “SU is one of the leading institutions in the country in LIGO. We should all take pride in our role in building very important pieces of the LIGO effort.”
- Lunchtime Lectures: Art on Campus
June 19, 2013 at 12:15 PM
Associate Director David Prince will present an examination of Emile Antoine Bourdelle's "Herakles" (1909), and Luise Meyers Kaish's "Saltine Warrior" (1951), each installed on the Shaw Quadrangle.------------------------
- Bookstore closed for year-end inventory
June 21, 2013 (All Day)
- FTES Course Selections Due
June 21, 2013 (All Day)
- Opening Reception for exhibition: Give and Take: The Currency of Culture
June 21, 2013 at 5:00 PM
Community Folk Art Center
- Movie Night - "Wreck-It-Ralph"
June 21, 2013 at 8:00 PM
- Summer 2013 Summer Session II Begins
July 1, 2013 (All Day)
- Summer 2013 Independence Day - No Classes
July 4, 2013 (All Day)
- Transfer Students Course Selection Deadline
July 5, 2013 (All Day)
- SU Gebbie Clinic enrolling kids for summer literacy camp
July 9, 2013 at 9:00 AM
621 Skytop Road
- Transfer Orientation Day
July 15, 2013 at 8:30 AM
- Arts and Sciences Events
AS Magazine, Fall 2012