Tech UPTechnologyCalculate the age of the universe with gravitational waves

Calculate the age of the universe with gravitational waves

Gravitational waves are vibrations that warp space-time, the fabric of which the universe is made, through which they travel. Einstein predicted their existence a century ago, and stated 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 around themselves.

The observation has confirmed the theories about gravity and space-time of the German physicist: in the last two years gravitational waves have been detected from at least five sources. The importance of this finding explains why 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 providing 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 are also used 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 around the world and by analyzing a gravitational wave they have estimated the age of the universe, which it would be between 11,900 and 15,700 million years. It will seem like a more than respectable time fork, 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 (christened 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.

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 is moving away from us, they calculated the time since the expansion of the cosmos began, that is, the age of the universe.

Measuring the time that 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 rebound speed of the galaxy to be estimated – which was also not too far.

Photo (NASA / ESA): Image of NGC4993, the galaxy where the gravitational wave GW170817 arose, used to measure the age of the universe. The source of the wave is the red dot located in the upper left margin of the center of the galaxy. In previous images it was not there.

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