April 18, 2006 7:20 PM PDT
Supercomputer simulates black hole collision
The NASA supercomputer Columbia just performed its largest astrophysical calculation ever: a 3D simulation of two black holes merging (click here to view video).
"This merger is a cataclysmic event, second only to the Big Bang in the amount of energy it produces," Joan Centrella, chief of the NASA Gravitational Astrophysics Laboratory in Greenbelt, Md., said Tuesday in a press teleconference.
NASA called the successful simulation a breakthrough in the observation of black holes and in the understanding of the entire universe. In fact, NASA claims that it might even provide the ultimate proof for Einstein's theory of general relativity.
Black holes occur when large stars burn up all their energy and collapse into bodies of enormous density. Their gravity is so strong that it absorbs everything around them--even light.
When two of these bodies collide, they emit more energy than the light of all the stars in the universe combined. Space shivers like a bowl of Jell-O around them, when gravitational waves spread at light speed. It is the pattern of these waves that NASA has now managed to simulate.
"Gravitational waves are going to give us an entirely new window on the universe," said Peter Saulson, a physics professor at Syracuse University involved in the project. He compared the results with the discovery of radio waves, infrared light and x-rays.
"Each time astronomers were able to open a new window, the universe showed a new face," he said. "Now that we are about to open up the gravitational wave window, we should again see a whole new different view of the universe."
Einstein explored the forces of gravity in his general relativity theory, predicting phenomena like black holes and gravitational radiation long before they could be proved. It is not until now, more than 90 years later, that scientists have managed to test these, back then inconceivable, predictions, Centrella said. "This has been a holy grail quest for the last 30 years."
Earlier trials failed since the equations based on Einstein's general relativity theory were so complicated that they made supercomputers crash; the enormous gravity of black holes cause disturbances in time and space, making time stop and space shrink and expand.
NASA researchers have managed to transform the theory into mathematical algorithms and run through it through Columbia, the fourth most powerful supercomputer in the world. Its 2,032 interconnected 512 Intel Itanium 2 processors ran for 80 hours, in an operation that would have taken 18 years for a single processor to perform.
The result was a model of the gravitational wave pattern of the black hole collision, which turned out to be the same regardless of the bodies' starting positions. Knowing the pattern, scientists can look for and interpret it in space, Centrella said.
"This is not something made up, like in a science-fiction movie," Centrella said. "We have confidence that these results are the real deal, that we have the true gravitational fingerprint predicted by Einstein for the black hole merger."
In fact, scientists are already out there looking. The National Science Foundation's Laser Interferometer Gravitational Wave Observatory (LIGO) in Hanford, Wash., is scanning space for the waves. Now they know what to look for, said Paul Hertz, chief scientist at NASA headquarters in Washington, D.C.
"Today we're throwing down the gauntlet for Einstein's theory of general relativity," Hertz said. "When LIGO detects gravitational waves from merging black holes, we will know whether Einstein's theory is right, or whether Einstein's theory is wrong."
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