Astrophysicists analyzed possible deviations from general relativity using data on the first recorded merger of neutron stars. In particular, they tested the hypothesis of the existence of large extra dimensions of space that can weaken gravity. The results obtained indicate that there are no such measurements. The preprint of the work is published on the arXiv.org server.
Gravity is significantly different from the other three fundamental interactions: strong, weak, and electromagnetic. It is described by the general theory of relativity, and so far scientists have not been able to incorporate gravity into a unified theory with other forces that are united by the Standard Model. In an attempt to explain these facts, theoretical physicists have put forward many different hypotheses, among which there are models in which there are large extra dimensions of space. The epithet "large" in this case means that they do not look like extra dimensions in superstring theory, the size of which is considered extremely small. According to these hypotheses, gravity "senses" more dimensions, which is why it turns out to be too weak in our four-dimensional space. At the same time, other interactions do not penetrate additional dimensions,because of which there is neither substance nor light.
In the new work, employees of gravitational-wave antennas Virgo and LIGO conducted tests of general relativity, including checking whether there are additional dimensions, since their presence should affect and weaken gravitational waves. To do this, the authors used the data of the event GW170817 - the first ever merger of neutron stars, which was recorded simultaneously by light and gravitational waves. The main criterion in this case should have been the disproportion between the decrease in the amplitude of electromagnetic and gravitational waves. Scientists have not recorded anything like this, which suggests that gravity exists in only four dimensions.
"In the upcoming sessions of observations on the Virgo and LIGO detectors, new mergers of double neutron stars should be recorded," the authors write in the article. "Together with electromagnetic observations, combining information from events with the emission of gravitational waves, including mergers of black holes, will lead to increasingly stringent constraints on deviations from general relativity, or, presumably, to potential indications of its shortcomings."