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Pulsar-dwarf star system shows Einstein more than relatively right

April 26, 2013|By Geoffrey Mohan
  • Researchers studying a distant binary system of a pulsating neutron star and a white dwarf proved that Einstein's General Relativity calculations hold up even in extreme gravitational conditions.
Researchers studying a distant binary system of a pulsating neutron star… (European Southern Observatory )

Albert Einstein has been dead for nearly 60 years, relatively speaking, and he’s still being tested. Theoretically, at least.

General relativity, the theory for which the German-born theoretical physicist is best known, holds up even in the more outlying phenomena of distant space, scientists have found.

Astronomers studied a neutron star about 7,000 light years from Earth that is twice as heavy as our sun but only about 12 miles in diameter. The gravity of this spinning, highly magnetic star, or pulsar, is about 300 billion times stronger than the force that’s holding your feet to the ground. A companion white dwarf is what remains of a much lighter star that is dying out.

The tightly spaced pulsar-dwarf pair, rotating around each other in under three hours, allows scientists to test alternative theories of gravity. It’s also a candidate for showing “deviations” in Einstein’s formulas. As the orbits decay, gravitational waves are emitted, sapping energy from the system. Astronomers used Einstein’s equations to calculate the amount of gravitational radiation emitted, then tested to see if it accurately predicted the rate of orbital decay.

"We thought this system might be extreme enough to show a breakdown in General Relativity, but instead, Einstein's predictions held up quite well," Paulo Freire of Germany's Max Planck Institute for Radioastronomy said in a written statement.

The long-run aim of such observations is to find a way to directly detect gravitational waves emitted by close-binary systems. The experiments helped the researchers better discern the characteristics of such emissions, which are extremely difficult to detect because they are difficult to differentiate from the “noise” of signals picked up by advanced telescopes.

It took a lot more than a village to prove Einstein right. Observers at the Green Bank Telescope in West Virginia discovered evidence of the pair. They were observed in visible light with the Apache Point telescope in New Mexico, the Very Large Telescope in Chile, and the William Herschel Telescope in the Canary Islands. Data were culled using the Arecibo telescope in Puerto Rico and the Effelsberg telescope in Germany.

The results were published Thursday in Science, 58 years and one week after Einstein’s death.

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