Catching waves: New SU super computer allows for black hole, gravity research

By: Kasey Panetta

Posted: 2/19/08

A new supercomputer being built by professors at Syracuse University's Department of Physics may help researchers detect gravitational waves created by the collision of black holes.

The computer, called SUGAR, short for Syracuse University Gravitation and Relativity Cluster, will be used to interpret data sent by the Laser Interferometer Gravitational-Wave Observatory (LIGO). LIGO is a project funded by the National Science Foundation to search for gravitational waves.

Peter Saulson, a professor of physics at SU, says the team will use SUGAR to understand the physics of whether or not gravitational waves exist.

"It will also let us explore the universe in a new way," he said. "Adding new tools to astronomy has been behind a huge number of the astronomical breakthroughs that have happened since 1945," Saulson said.

Duncan Brown, associate professor of physics at SU, explained a gravitational wave is what happens when there is a large black hole, with another hole going around it.

"That generates ripples of space time that propagate outward and carry energy away," he said. "And eventually they crash into each other."

Gravitational waves, unlike electromagnetic waves emitted by items such as cell phones, are incredibly difficult to detect because of their small sizes.

"Because these waves are so small, Brown said. "It's really hard to detect. You need massive black holes going round and round at the speed of light in order to detect them."

Gravity waves would be the best way to examine the Big Bang, said Saulson, who's been working with gravitational waves since 1981.

"The prospects for gravity waves are pretty dramatic," he said.

The computer itself is an impressive piece of machinery requiring the installation of two air conditioning units and additional power. It consists of 80 nodes and various screens that allow researches to log into the system.

"Each node has 2.4 gigahertz," Brown said. "The MacBook Pro probably has about two gigahertz, and each node is a bit faster than two of [the MacBook Pro] and has about four times the RAM."

LIGO, which is part of an international collaboration that operates two facilities in the United States, uses an elaborate system of mirrors and lasers created by scientists from the California Institute of Technology (Caltech) and the Massachusetts Institute of Technology (MIT) to detect the waves. The problem is the excess noise created by the vibrations due to the high temperature of the laser and various other noise sources.

"The reason we are building the computer is to analyze data and sift through the noise sources and try to find the one we are looking for," Brown said.

Albert Einstein predicted the existence of the waves in his Theory of Relativity, but it has taken decades to create the technology. "You need incredibly sensitive detectors to detect them," Brown said. "The amount of scientific manpower needed to do this is huge."

The computer will actually serve two purposes once it is completed. The first purpose will be to model the signal in collaboration with a Caltech-Cornell project called Simulating eXtreme Spacetimes (SXS). Researchers will use the computer to figure out what black holes are doing and the pattern created by gravitational waves.

"We're trying to figure out what we are looking for…it's hard to do on paper," Brown said.

Although approximations can be calculated, the exact equations are too complicated to be determined by pencil and paper, he said.

The second purpose for the computer will use both the theoretical calculations created by the computer and the approximations done by the researchers to sift through the noisy data sent by LIGO to look for certain patterns that are impossible for the human ear to detect.

The researchers are excited about what the computer may mean to the scientific community.

Josh Smith, a research associate in the physics department, said SUGAR will make a strong contribution to LIGO's effort to find gravitational waves.

Smith was an undergraduate student at SU when research was being done for the LIGO mirrors. "It's kind of cool for me to see the groups focus shift to more of gravitational wave data analysis," he said.

The computer shows a significant advancement and change in scientists' understanding of the universe.

Saulson said ever since Einstein made his predictions about gravity waves, scientists have wondered if they could actually show whether the waves spread through space time, away from accelerate masses. This demonstration can help determine how gravity works.

"Detecting gravity waves is going to let us explore the universe in a new way," Saulson said.

kpanetta@syr.edu