22.7.08

Pulsar's wobble provides new Einstein test

Einstein can rest easy for a bit longer. Using a pair of orbiting pulsars, astronomers have confirmed a prediction of general relativity about how bodies wobble in the presence of gravity.

But in the future, the unique test will become more precise, potentially revealing deviations from the long-held theory. Pulsars are collapsed stars made mostly of neutrons. Each spins around an axis and shines bright beams of light from its poles. Because the stars are dense and tend to orbit any partners at close distances, strong gravitational fields are at work, making them ideal to test a number of predictions of Einstein's theory of general relativity.

Now, a team has confirmed an old prediction that the warping of space should induce a subtle wiggle in a star's spin. This "spin precession" causes its main axis to trace a circle over time, like a spinning top. "This measurement is the first clear quantitative test of spin precession in a star or a body outside the solar system," says study author Rene Breton of McGill University in Montreal, Canada.


from New Scientist
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