Thu Apr 25, 2013 1:00 pm (PDT) . Posted by:
April 25, 2013, 2:38 p.m. ET
Einstein Proved Right on Gravity—Again
By GAUTAM NAIK
Scientists have subjected Albert Einstein’
For example, a bowling ball causes a dent in a mattress, and that dent changes the otherwise straight motion of a nearby marble on the same mattress. Similarly, the mass of the sun distorts the space-time around it. A body with less mass, like the earth, travels along one path in that distorted space, which we call its orbit.
Scientists aren’t testing the general theory because they think it is wrong but rather because they are certain it can’t be the final explanation—just as Isaac Newton’s notion of gravitational force was superseded by Einstein’
Consider that for a black hole, Einstein’
Dr. Freire and his colleagues put Einstein to the test in a cosmic laboratory 7,000 light years from earth, where two exotic stars are circling each other.
Physicist Albert Einstein.
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One, known as a white dwarf, is the cooling remnant of a much lighter star. Its companion is a pulsar, which spins 25 times every second. Though the pulsar is just 12 miles across, it weighs twice as much as the sun.
“When you have such a big mass in such a small space you have extremely high gravity,” said Charles Wang, a theoretical physicist at the University of Aberdeen, Scotland, who wasn’t involved in the study.
The gravity on the pulsar’s surface is 300 billion times as great as the gravity on Earth. The conditions there approach the relentless, overwhelming power of a black hole, which swallows even light.
The pulsar and white dwarf pair emit gravitational waves and the binary star system gradually loses energy. As a result, the stars will move closer to each other and orbit faster.
Dr. Freire’s and his colleagues used several telescopes to take precise measurements about the two-star system. Their results perfectly matched the Einstein-based prediction.
Write to Gautam Naik at gautam.naik@