Trio of dead stars upholds a key part of Einstein’s theory of gravity | Science News

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Trio of dead stars upholds a key part of Einstein’s theory of gravity

Celestial orbital dance conforms with physicists’ expectations for ultradense objects

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4:19pm, January 12, 2018
dead stars illustration

TRIPLE THREAT  A threesome of dead stars has allowed a new test of a tenet of Einstein’s theory of gravity. The trio includes a pulsar (illustrated, with bands of electromagnetic radiation in blue) in orbit with a nearby white dwarf. A second white dwarf orbits farther afield (red, upper right).

OXON HILL, Md. — Observations of a trio of dead stars have confirmed that a foundation of Einstein’s gravitational theory holds even for ultradense objects with strong gravitational fields.

The complex orbital dance of the three former stars conforms to a rule known as the strong equivalence principle, researchers reported January 10 at a meeting of the American Astronomical Society. That agreement limits theories that predict Einstein’s theory, general relativity, should fail at some level.

According to general relativity, an object’s composition has no impact on how gravity pulls on it: Earth’s gravity accelerates a sphere of iron at the same rate as a sphere of lead. That’s what’s known as the weak equivalence principle. A slew of experiments have confirmed that principle — beginning with Galileo

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