March 7, 2021

Yes, Einstein was right


Einstein was right. That said, it looks like a truism. Einstein, the greatest scientist who have given the centuries, one of the most intelligent men who have trodden the Earth, how can he not be right? I would always have it.

But things are not so simple. His theory of Relativity is a prodigy of cosmological physics, a monument to mathematical theorization, but an ordeal for those who have wanted to prove it. To verify that his ideas were true (that they were) the best method would be to enclose the entire cosmos in a laboratory and test about it: changing measures, forces, components … Everything indicates that we did that exercise, which is the same which is done to check any physical phenomenon, it would be that Einstein is right. But it is obvious that experimental exercise size is impossible. That is why, since more than 100 years ago Albert launched his ideas into the world, science is determined to demonstrate them by more feasible means. And it does. Last time, today when A team of scientists, including Spanish experts, made public the results of its 26-year follow-up of the S2 star, 26,000 light years from Earth. And yes, Einstein was right.

The theory of general relativity holds that gravity is nothing other than the effect of curvature in space and time. When an object attracts another in the cosmos, it is not because a kind of thread of invisible particles pulls them. The effect, rather, resembles that of a mat in which we sit three children. Two thin at the ends and one heavier in the center. The first ones will fall towards the side of the most voluminous by the curvature that this one will realize in the mat.

This theory has been the best description ever made of how gravity works. But for a theory to be true, it must work wherever it is tested: both in the children's mat and inside the center of a galaxy.

In study published today in Science He chose the hardest part: the center of a galaxy. In fact, this work is one of only two made on the S2 star that circulates centers of Sagittarius A, the black hole in the center of the Milky Way.

26,000 light years from our planet, Sagittarius A is a supermassive hole with a mass equivalent to four million suns like the one that illuminates us every morning. These holes have a gravitational attraction such that they absorb everything that approaches them, including light. It is very difficult, if not impossible, to measure how Einstein's theories of gravity work in a black hole. But they can be checked indirectly by observing the effect it causes on the surrounding stars. It's like determining the speed at which a crashed car was going by the size of the tracks it left when braking.

The star S2 draws a very pronounced ellipse around Sagittarius A. At its closest point, it is only 3 times the distance between the Sun and Pluto. At that distance, according to Einstein's theory, the photons emitted by the star should suffer a loss of energy, as if the hole was absorbing the star's light.

How can we show that this is really happening?

The experts involved in the experiment, including researchers from the CSIC at the Institute of Astrophysics of Andalusia, have searched the mark that leaves that loss of energy. It is what is called gravitational redshift.

Scientists have investigated the behavior of S2 photons on their way to Earth. The matter is not simple because a photon takes 26,000 years to reach our planet from S2. Even so, it has been possible for the first time to confirm that the 2018 observations on the redshifts of the radiation coming from that star are correct.

The key to the finding is the study of the spectrum of light radiation emitted by the star. That spectrum is like a rainbow loaded with information at different wavelengths and has been collected at the W.M Keck Observatory in Hawaii using a powerful spectrograph. The spectral analysis allows to know the movement of the stars with unprecedented precision. Combining this study with the real images of the star you can have a very good idea of ​​the way in which it moves around the black hole that wants to devour it.

Einstein predicted that in the vicinity of a black hole, the light has to do extra work to travel, as if a runner carried a weight on his back. The weight is the extreme gravity that pulls the light towards the jaws of the hole. The variations of the light spectrum can not only indicate the speed at which a star moves, but also realize the energy used by the photons emitted to travel.

After years of collating data and observations, the team of astronomers involved in this project has been able to confirm that these variations in the vicinity of Sagittarius A match the effect of gravity predicted by the German scientist in his 1905 theory.

The new publication throws complementary measures to others taken in recent years. But those presented some deficiencies that made them little refutable. In this case, the observations are not subject to error and, therefore, yes, once again we can say that Einstein was right.

. (tagsToTranslate) Jorge Mayor



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