The ‘tsunami’ of gravitational waves that could change what we know about the Universe

A phenomenon that Einstein predicted more than a hundred years ago and that was first observed in 2015 now sets a new record.

These are gravitational waves, ripples in the structure of spacetime that occur when two hypermassive objects, such as black holes, collide violently.

A recent survey by hundreds of scientists at the Ligo observatories, in the United States, Virgo, in Italy, and Kagra, in Japan, claims to have detected the greatest number of gravitational waves to date.

This discovery could help solve some of the most complex puzzles in the universe, including the fundamental components of matter and the workings of space and time.

“This really is a new era for the detection of gravitational waves,” said Susan Scott, a researcher at the Center for Gravitational Astrophysics at the National University of Australia and one of the study’s authors, said in a statement.

“It’s a huge step forward in our quest to discover the secrets of the universe’s evolution,” said the expert.

The publication with the results of the observations is still under review, but with this announcement, the “future of the Ligo-Virgo-Kagra collaboration is very promising”, Eduard Larrañaga, theoretical physicist and professor at the National Observatory, told BBC News Mundo at Colombia, which did not participate in the study.

A tsunami of gravitational waves

The collaborative work Ligo-Virgo-Kagra detected 35 new gravitational waves between November 2019 and March 2020.

This amount is more than ten times the number of gravitational waves that Ligo-Virgo detected in its first round of observations, which took place over four months, between 2015 and 2016.

It’s “a tsunami,” says Scott.

Of the 35 waves detected, 32 are the result of collisions between melting black holes and three correspond to collisions between neutron stars and black holes.

These monumental collisions occurred mostly billions of light years away, creating ripples across spacetime.

With this discovery, there are already 90 gravitational waves detected between 2015 and 2020.

What are gravitational waves?

When cosmic objects move or collide, they create a ripple in the structure of spacetime, which spreads out like a wave in lake water. This phenomenon is called a gravitational wave.

Gravitational waves stretch spacetime in one direction and compress it in another.

Albert Einstein theoretically predicted the existence of gravitational waves, as part of his theory of general relativity, in 1916.

Einstein calculated that, upon reaching Earth, these waves would be so weak that they could never be detected.

In 2015, however, the first detection of a gravitational wave was performed.

Gravitational waves allow us to have a broader view of the universe, as they do not limit observations to objects that emit light or particles, but allow us to detect objects based on the disturbances they generate in space-time.

Diversity

This new catalog of gravitational waves is the key to understanding the nature of black holes and the evolution of stars.

“We are just now beginning to appreciate the wonderful diversity of black holes and neutron stars,” Christopher Berry, an astronomer at the University of Glasgow’s Institute for Gravitational Research, said in a statement.

Observations, for example, showed that gravitational waves were the result of the fusion of black rays that together reached a mass more than a hundred times greater than that of the Sun, while others were less than 20 times greater.

Scott, for his part, argues that observing the mass and spin of merging black holes allows us to see how these binary systems arise.

sensitivity

Ligo-Virgo-Kagra registration was made possible by the advancement of science and technology in the detection of gravitational waves.

Gravitational wave detectors work with high-powered lasers that measure with high precision the time it takes for light to travel between two L-shaped arms.

When a gravitational wave hits Earth, it compresses spacetime in one direction and stretches it in the other, breaking the path of the lasers.

Detectors such as Ligo (Laser Interferometer Gravitational-Wave Observatory, or Observatory of Gravitational Waves by Laser Interferometer, in free translation) are capable of detecting these disturbances that occur at subatomic scales.

Since 2015, these instruments have become more sensitive, allowing more waves to be detected.

According to Scott, increasing the sensitivity of detectors over time will allow the identification of new sources of gravitational waves, some of which are unexpected.

One of these sources could be, for example, the gravitational radiation generated by the Big Bang itself.