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Einstein's understanding of gravity, as described in his general theory of relativity, predicts that all objects fall at the same rate, regardless of their mbad or composition. This theory has pbaded a test after the other here on Earth, but is it still true for some of the most mbadive and densest objects in the known universe, an aspect of nature known as the Principle of Strong Equivalence?
gave this persistent question its most rigorous test. Their findings, published in the journal Nature, show that Einstein's ideas on gravity continue to dominate even in one of the most extreme scenarios that the Universe can offer.
In 2011, NSF's Green Bank Telescope (GBT)) discovered a natural laboratory to test this theory under extreme conditions: a triple star system called PSR J0337 + 1715, located about 4,200 light-years away. Earth. This system contains a neutron star in a 1.6-day orbit with a white dwarf star, and the pair in a 327-day orbit with another white dwarf further away
"This is a star system unique, "said Ryan Lynch of the Green Bank Observatory in West Virginia, and co-author on the paper. "We do not know anyone else like that, it makes it a unique laboratory to test Einstein's theories."
Since its discovery, the triple system has been observed regularly by the GBT, the Westerbork Synthesis Radio Telescope in the Netherlands, and the NSF Arecibo Observatory in Puerto Rico. The GBT has spent more than 400 hours observing this system, taking data and calculating how each object is moving relative to the other.
How did these telescopes study this system? This particular neutron star is actually a pulsar. Many pulsars rotate with a constancy that rivals some of the most accurate atomic clocks on Earth. "As one of the most sensitive radio telescopes in the world, the GBT is ready to capture these weak radio wave pulses to study extreme physics," Lynch said. The neutron star of this system pulses (rotates) 366 times per second
"We can explain each pulse of the neutron star since we began our observations," said Anne Archibald of the University of Amsterdam and Radio Astronomy and lead author on paper. "We can say its location a few hundred meters away.This is a very accurate track of where the neutron star has been and where it is going."
If the alternatives to Einstein's gravitational image were correct, so the neutron star and the inner white dwarf would fall differently to the white dwarf exterior. "The internal white dwarf is not as mbadive or compact as the neutron star, and therefore has less gravitational binding energy," said Scott Ransom, astronomer at the Observatory. National Radioastronomy Institute in Charlottesville, Virginia.
Through meticulous observations and careful calculations, the team was able to test the severity of the system using the neutron star pulses alone. They found that any difference in acceleration between the neutron star and the inner white dwarf is too small to be detected.
"If there is a difference, it does not exceed three parts in a million," says co-author Nina Gusinskaia of the University of Amsterdam. This imposes severe constraints on all alternative theories to general relativity
This result is ten times more accurate than the previous previous gravity test, which makes the evidence of the Strong Equivalence Principle of & # 039; 39; Einstein much stronger
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