The neutron star 4,200 light-years proves that Einstein's gravity principle is correct

If we dropped a marble ball and a bowling ball from the 44th floor of a skyscraper in Manhattan they would fall at the same time. 19659003] The same principle is true even for all objects, regardless of their mass, according to the gravity principle of Einstein's theory of relativity. This is what we call the principle of strong equivalence, which states that all objects fall at the same rate, notwithstanding their mass or composition.

This has been proven for a long time in the celestial objects of the solar system. Earth and Jupiter, for example, "fall" both at the same rate to the sun even though they have very different masses. Astronomer Dave Scott demonstrated it with a hammer and feather falling at the same rate on the moon.

Even in the most extreme conditions, the principle is there. This has been proven by a team of international researchers after rigorous observations of the behavior of a rare star system at only 4,200 light years from Earth.

The rare triple star system proves the principle of equivalence

In West Virginia, the star system was detected for the first time at 4,200 light-years from Earth in the constellation of the Taurus. Scientists have dubbed the star system PSR J0337 + 1715, which consists of a neutron star in a 1.6 day orbit around a white dwarf. Both are also in a 327-day orbit around a second white dwarf further away.

A neutron star is the remains of a star after it exploded and collapsed on itself. It's usually never bigger than a city on Earth, but it contains the same amount of mass as the sun. A tablespoon of a neutron star is about as heavy as Mount Everest.

Because of its extreme density, a neutron star has a strong gravitational field, making it one of the most extreme environments. What further raises the stakes, is the existence of two white dwarfs

The white dwarfs are small stars the size of a planet. A white dwarf is a star that has exhausted all its fuel of which only a hot core remains. White dwarfs usually have a mass of one fifth of the sun.

Because they do not have a gravitational force as strong as neutron stars, the researchers found it intriguing to find two white dwarfs in the vicinity of a neutron star. Few objects can survive the explosive death of a star.

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

Studying the Radio Pulse of a Neutron Star

In a new article published in the journal Nature, researchers found that the inner stars accelerated at the same speed, giving the most accurate proof still gravity, as Einstein has described. They also observed that the second white dwarf did not affect the movement of internal stars in any way.

The researchers were able to reach this conclusion by studying the movements of the neutron star. When a neutron star turns, it becomes a pulsar. This radiates radio waves, X-rays, and even visible lights as it rotates.

This pulsar, in particular, rotates at a very fast rate of 366 rotations per second. With each rotation, the pulsar sends radio wave pulses that can be detected on Earth using sophisticated radio equipment.

In six years, researchers have observed pulsar movement using the Westerbork Synthesis radio telescope. in the Netherlands, the Observatory of Arecibo in Puerto Rico and the Green Bank Telescope.

"We can explain every pulse of the neutron star since we started our observations," says lead author Anne Archibald of the University of Amsterdam. the Netherlands Institute of Radioastronomy. "We can say its position a few hundred meters away, it's really a precise track of where the neutron star was and where it goes."

As the pulsar rotates faster, it sends more impulses that make a more accurate tracking of its location. If it accelerates at a different pace than the white dwarf, researchers would have seen impulses arrive at different times than they expected.

In fact, the difference in speed of acceleration between the pulsar and the white dwarf is so small that it is almost impossible to detect it. The researchers say that the difference does not exceed three parts per million.

Alternative theories to gravity

Einstein described gravity as a curve in the space-time that objects follow when they "fall" toward each other . This can be demonstrated in the curved orbit of the moon around the Earth and planets around the sun.

However, some experts are not convinced by the idea that gravity is a curve. This is why they have proposed alternative theories that can explain how gravity behaves in extreme conditions.

The latest research, however, makes it much harder to disprove Einstein's predictions. The researchers admit that their findings are not indisputable proof of Einstein's gravity. Objects with very, very small levels, for example, still have to reveal how they behave with gravity.

"We did better with this system than the previous tests by a factor of 10," says co-author and physicist David Kaplan of the University of Wisconsin-Milwaukee. "But this is not a foolproof answer: the reconciliation of gravitation with quantum mechanics is not yet solved."

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