Computer for the stars
Archived article from Nov 18, 2002
By Joseph Blumberg
With the abundance of Apples in the world of computing, it was only a matter of time before there was a Grape - in reality, an acronym for GRAvity piPE. This is a highly specialized supercomputer developed by astrophysicists at the University of Tokyo to calculate the gravitational forces between stars - lots of stars - all at once. The Grape does just this one thing, but it does it exceedingly well.
A Grape-6 recently arrived at Rutgers' department of physics and is one of only nine machines deployed worldwide. It has a speed rating of one teraflop, meaning it can perform one trillion calculations per second. That is 10 times faster than the interconnected pair of Sun Microsystems E10000 supercomputers in Rutgers' High Performance Computing Facility.
"This makes the Grape the fastest computer at Rutgers, and it is likely to remain so for the foreseeable future," said Professor David Merritt, a leading black hole researcher and the moving force behind the Grape-6 acquisition.
The purchase was funded primarily by the Space Telescope Science Institute, the group that manages the scientific operation of the Hubble Space Telescope for NASA, with additional funding from NASA itself. The Grape-6 costs about $100,000, far less than the $7 million price tag on the Sun E10000 system.
"But you must keep in mind that the Grape can only calculate gravitational forces," said Assistant Professor Raul Jimenez, another Rutgers astrophysicist. "It only knows how to do certain kinds of operations and, while it is fast, it can't do the variety of processing tasks performed by the E10000."
The Grape is designed primarily to simulate galaxies, and that is just what Merritt needs. Ą°IĄŻll be using the Grape to look at the dynamics of the stars around a black hole to better understand the effects black holes have on galaxies,Ą± said Merritt.
Merritt is "itching to start" using the Grape to simulate triple black holes. These arise from a galaxy with a binary or double black hole, formed through a previous merger of two galaxies, then merging with a third galaxy with its own black hole. "The three black holes interact in a very chaotic way, in the process messing up the distribution of stars around them," he explained. "That's a very good problem for this machine," said Merritt, with keen anticipation in his voice.
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