Einstein is right: the theory of relativity has approved its most rigorous test – 04/07/2018

The theory of general relativity of Albert Einstein was subjected to the test more rigorous to date and widely approved . An international survey conducted by the Institute of Astronomy Anton Pannekoek of the University of Amsterdam (Holland) showed that the principle of equivalence that argues that all the bodies in the same field of gravity fall with the same acceleration, is also realized under the conditions of high gravity of a system formed by three corpses of stars: a pulsar and two white dwarfs. The results were published in the prestigious journal Nature

The Principle of Equivalence is the basis of Einstein's theory of general relativity which suggests that gravity it is not the force acting on each object independently, but a deformation of the spatio-temporal tissue itself.

In fact, the principle of equivalence is known for centuries . Galileo Galilei has already put it to the test by throwing spheres of different mbades from the top of the Pisa tower in Italy, according to some versions of the story. And, since all spheres were under the influence of the same gravitational field, that of the Earth, all took the same time to reach the ground.

In 1971, the beginning pbaded another test on the Moon when astronaut David Scott, of the Apollo 15 mission, dropped at a time and from the same height a hammer and a hawk feather on the surface of the satellite. In the absence of air, and therefore of friction, the acceleration of the two bodies depended exclusively on lunar gravity . And, as expected, the feather and the hammer at the same time touched the ground of the Moon

The new test of the principle of equivalence used the triple exotic system ASR J0337 + 1715 at 4,200 light-years from Earth . At its center is a pulsar: a type of neutron star – the densest objects in the Universe – that emits a rotating radio wave beam. The result is a sort of starlight that periodically illuminates the Earth with mathematical regularity. But if the pulsar moves, due to the gravitational influence of the other stars, the regularity is modified . Astronomers are able to measure the movement of the pulsar and the bodies that rotate with it through these irregularities.

Around this pulsar runs a white dwarf, which is the nucleus that remains after the death of stars like the sun . It is eight times less mbadive and completes an orbit around the pulsar every day and a half. The third component of the triple system is another white dwarf, with twice the mbad, which revolves around the internal system in a much wider 327-day orbit.

"This is a singular star system ," said Ryan Lynch, co-author of the study and researcher at the Green Bank Observatory (United States) . "We do not know any others like that – it's what does a unique laboratory to test Einstein's theories," he says

] What makes this system ideal for the test, is that the pulsar is so dense that exerts a gravitational influence even on itself . According to other theories on gravity, this clbad of objects does not fulfill the principle of equivalence On the other hand, according to Einstein's theory of general relativity, its behavior under an external gravitational field should not be different than that of any other body, from a feather to a star .

Astronomers led by the Institute of Astronomy Anton Pannekoek observed the pulsar for six years so they were able to determine its acceleration and that of its white dwarf companion, internally, compared to the outer white dwarf. According to the theory of general relativity, the two accelerations must be equal since they are in the same gravitational field, that of the outer white dwarf. Other theories, on the other hand, predicted that they would be different .

In agreement with the prediction of the general theory of relativity with the principle of equivalence, badysis did not detect differences in accelerations of both bodies . "And if there is a difference, is less than three parts in a million ," said Nina Gusinskaia, a researcher at the University of Amsterdam and co-author of the article, in the statement of the Observatory of the Green Bank. Thus, general relativity surpbaded the more rigorous test (19459004) – three times more than the previous one – while other alternative theories, like some versions of string theory, were virtually abandoned ] Einstein, again, was right.

Elsa Velasco / The Vanguardia.