Einstein's prediction came true in a binary system of stars: scientists discovered gravitational redshift

Astronomers have discovered gravitational redshift

The astronomers were able to detect the phenomenon predicted by Albert Einstein in outer space. For the first time, they were able to observe an effect known as gravitational redshift. It is critical to maintaining effective GPS performance on the Earth. Unexpectedly for the astronomers, this effect was observed in the star system of our Galaxy. Einstein predicted that, in the theory, gravitational redshift could exist, and with it, in fact, the light could turn red as it begins to be influenced by gravity.

It can happen as the wavelength of the photon or the light particle gets longer. In that case, it appears redder as it moves away from the gravity pit. In space, objects that are much larger than the Earth create a certain force of gravity, that is called a gravity well.


When this effect occurs, the clock slows down on the surface of the Earth. Just like a watch that is at a distance, it experiences, because its pace slows down. This phenomenon can be observed on orbiting satellites. Because of that, the redshift must be taken into account when calculating the position on the Earth using GPS.

Now the scientists were able to find absolute evidence of the fact that this effect observed in our Solar System is present. Previously, it was considered only as a hypothesis and assumption, now evidence has been found for this phenomenon.

In their new study, the astronomers were able to detect the gravitational redshift in a two-star system at a distance of 29 thousand light years called 4U 1916-053. This system has a dense core that is left of a star with the outer layers removed.


And there is a neutron star, very dense, formed during a supernova. This pair orbits at a distance of 346 thousand kilometers from each other, roughly like the Earth and the Moon. NASA equipment was able not only to detect this unique star system, but also to observe the effects of gravitational redshift in it.

This work was accepted for publication to the Astrophysical Journal Letter; a version of the paper was uploaded to the preprint server arXiv.org on Aug. 3.