Gravitational waves are vibrations that deform space-time, the fabric of which the universe is made, through which they travel. Einstein predicted its existence a century ago, and explained in your General Theory of Relativity that they would be produced by cosmic objects such as black holes or pulsars, dense and compact stars that rotate on themselves.
The observation has confirmed the German physicist’s theories about gravity and space-time: gravitational waves from at least five sources have been detected in the last two years. The importance of this finding explains that the 2017 Nobel Prize in Physics went to American scientists Rainer Weiss, Barry Barish and Kip Thorne for their work on LIGO, the gravitational wave detector.
The study of this phenomenon is bringing new knowledge about the formation of massive stars, gamma-ray bursts, the characteristics of neutron stars or even the origin of heavy elements such as gold.
In addition, gravitational waves also serve to calculate the age of the cosmos.
Old as time
Peter Blanchard, Tarreneh Eftekhari, Victoria Villar and Peter Williams, astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA), have collaborated with 1,314 other scientists from all over the world and through the analysis of a gravitational wave have estimated the age of the universe, which it would be between 11,900 and 15,700 million years. It will seem like a fork of time more than respectable, but given the difficulty of the work, it is a remarkable achievement.
How have they done it? They have been based on the study of a single gravitational wave signal (named GW170817), observed by the LIGO and Virgo detectors on August 17, 2017. It was produced by two binary neutron stars at the time of their orbital collapse, which led to merge.
The astronomers identified the origin of the phenomenon: the galaxy NGC4993, located about 140 million light years from Earth. Based on the wave and the speed at which this galaxy moves away from us, they calculated the time passed since the expansion of the cosmos began, that is, the age of the universe.
Measuring the time the cosmos has is not possible with any type of gravitational wave, which gives relevance to this research, published in the journal Nature. In this case, there was an optical identification of the source -which allowed the speed of the galaxy’s distance to be estimated-, which was also not too far away.