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Einstein in the Sky With Pulsars
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Courtesy of Michael Kramer (Jodrell Bank Observatory, University of Manchester) |
Lyne’s object consists of two pulsars, extremely dense stellar cinders that emit beams of radiation as they spin. As the stars swoop around each other once every two and half hours, theory predicts, they emit a torrent of gravitational waves that suck out energy and subtly cause the pulsars to speed up. Measuring the orbital period should be easy because during each circuit the larger pulsar—more massive than the sun yet just 12 miles in diameter—detectably distorts radiation from the smaller one. By studying the motions of the two stars, Lyne has confirmed the quickening orbit and deduced three other ways to measure the effects of general relativity. So far all of the data seem to confirm Einstein’s predictions. But Lyne is looking for minuscule deviations that could reveal where Einstein’s ideas remain incomplete. “Over the next few years we’ll be able to improve the precision of our data sets, and it’s quite possible that Einstein’s theory may need to be adjusted a bit,” he says.