Einstein's theory of gravity passes an extreme test

Einstein's general theory of relativity predicts that all objects fall at the same rate, regardless of their mass or composition. For example, if we drop at the same time a ball and a cannonball from the leaning tower of Pisa, the two objects will hit the ground at the same time, despite the fact that the gun is a heavier object.

As we know, gravitation works according to Einstein's general theory of relativity because it has been proven correct on earth again and again. However, the theory has not been well tested over very large distances and astronomically large scale. Scientists did not know if Einstein's theory was true for objects of extreme gravity.

Alternative theories predict that objects with extreme gravitational environments, such as neutron stars, fall a little differently from objects of lighter mass. When the researchers tested the theory under extreme conditions in a triple star system, they found that gravity still works the same way as on Earth

The subject of the test, called PSR J0337 + 1715, is located approximately 4,200 light-years away. Earth. The rare trio was discovered in 2011 and consists of a neutron star accompanied by a white dwarf. The pair revolves around a common center of mass every 1.6 terrestrial days. It is also in a 327-day orbit with another white dwarf, which is much further away.

"It's a unique star system," said co-author Ryan Lynch of Green Bank Observatory in West Virginia. "We do not know any other alike, making it a unique laboratory to test Einstein's theories."

The triple system has been observed regularly by terrestrial telescopes. Their center of interest is the neutron star. This particular neutron star is actually a pulsar that rotates rapidly, 366 times per second and emits X-rays and radio waves. These radio pulses were used to track the position of the neutron star.

"We can explain every pulse of the neutron star since we started our observations," says lead author Anne Archibald of the University of Amsterdam. "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 gravity theory was correct, the neutron star was falling differently from the white dwarf and impulses but this kind of difference has not been observed so far.