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NASA Simulation Beats Gravity Wave Overloads
Greenbelt MD (SPX) Apr 18, 2006 NASA scientists said Tuesday they have developed a new computer model that can simulate the gravitational waves generated by merging black holes without crashing. The three-dimensional simulations represent the largest astrophysical calculations ever performed on a NASA supercomputer, the space agency said in a statement. Einstein hypothesized that when two massive black holes merge, the event vibrates the very fabric of space as gravitational waves race away from the collision at light speed. Previous attempts at simulating black-hole mergers had been plagued by computer crashes, because Einstein's relativity requires a type of mathematics called tensor calculus, which cannot easily be turned into programming instructions. The scientists, at NASA's Goddard Space Flight Center, found a method of making the math more computer-friendly. Results of the simulations, performed on the Columbia supercomputer at NASA's Ames Research Center near Mountain View, Calif., appeared in the March 26 issue of Physical Review Letters and will appear in an upcoming issue of Physical Review. The lead author is John Baker of Goddard. "These mergers are by far the most powerful events occurring in the universe, with each one generating more energy than all of the stars in the universe combined," said Joan Centrella, head of the Gravitational Astrophysics Laboratory at Goddard. "Now we have realistic simulations to guide gravitational wave detectors coming online." Similar to ripples on a pond, Einstein said gravitational waves are ripples in space and time - a four-dimensional concept that not yet been directly detected. Because gravitational waves interact with matter only weakly, they can penetrate the dust and gas that blocks optical observations of black holes and other objects. Therefore, they could offer scientists a new window to explore the universe and provide a precise test of Einstein's relativity theory. The key to studying these massive colliding objects is the fact that they produce gravitational waves of differing wavelengths and strengths, depending on their individual masses. The Goddard team first perfected a simulation of merging, equal-mass, non-spinning black holes starting at various positions corresponding to the last two to five orbits before their merger. With each simulation run, regardless of the starting point, the black holes orbited stably and produced identical waveforms during the collision and its aftermath. This unprecedented combination of stability and reproducibility assured the scientists that the simulations were true to Einstein's equations. The team has since moved on to simulating mergers of non-equal-mass black holes. Related Links Black Hole Animation
Towards A New Test Of General Relativity
Paris, France (SPX) Mar 24, 2006Scientists funded by the European Space Agency have measured the gravitational equivalent of a magnetic field for the first time in a laboratory. Under certain special conditions the effect is much larger than expected from general relativity and could help physicists to make a significant step towards the long-sought-after quantum theory of gravity. |
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