PHYSICS NEWS UPDATE

The American Institute of Physics Bulletin of Physics News

Number 771 March 29, 2006 by Phillip F. Schewe, Ben Stein, and
Davide Castelvecchi

BLACK HOLE MERGER MOVIE. Accurate calculations of the gravitational
waveforms emitted during the collision of black holes can now be
made. A new computer study of how a pair of black holes, circling
each other, disturbs the surrounding space and sends huge gusts of
gravitational waves outwards, should greatly benefit the
experimental search for those waves with detectors like LIGO and
LISA. The relative difficulty of computer modeling of complicated
physical behavior depends partly on the system in question and on
the equations that describe the forces at work. To describe the
complicated configuration of charges and currents, one uses
Maxwell's equations to determine the forces at work. In the case of
black-hole binaries, the equations are those from Albert Einstein's
theory of general relativity. Black holes encapsulate the ultimate
in gravitational forces, and this presents difficulties for
computations attempting to model behavior nearby. Nevertheless,
some physicists at the University of Texas at Brownsville have now
derived an algorithm that not only produces accurate estimates of
the gravity waves of the inspiraling black holes, even over the
short time intervals leading up to the final merger, but also is
easily implemented on computers (see figures and movie at
www.aip.org/png/2006/256.htm ). "The importance of this work,"
says Carlos Lousto, one of the authors of the new study, "is that it
gives an accurate prediction to the gravitational wave
observatories, such as LIGO, of what they are going to observe."

The new results are part of a larger study of numerical relativity
carried out at the University of Texas, work referred to as the
Lazarus Project

(http://www.phys.utb.edu/numrel/research_dir/lazarus.html ).

(Campanelli, Lousto, Marronetti, and Zlochower; Physical Review
Letters, 24 March 2006; contact information, lousto@phys.utb.edu,
956-882-6651)

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