Whenever a new instrument was invented to study the sky, astronomers had to rethink their understanding of the cosmos. More recently, scientists have triggered a revolution in astronomy by finding out how gravitational waves can be observed using lasers and mirrors using a new technology.
Black holes are the shells of massive stars whose gravity is so strong that not even light can escape from them. When they collide, they release energy in a form called gravitational waves. The collisions, which are completely invisible to the naked eye and do not register in the electromagnetic spectrum, can only be detected by observing gravitational waves. While Albert Einstein predicted the existence of the waves in 1
916, it took almost a century for scientists to actually observe them.
On September 14, 2015, the entire universe shook. Well, actually, it is more accurate to say that this was the day humanity became aware of a catastrophic event – the conflation of two massive black holes that were created about 1.3 billion years ago – or, by making Star Wars one Line stolen "a long time ago in a faraway galaxy."
As the gravitational waves, which were triggered 1.3 billion years ago during the merger with the black hole, flooded the solar system, the fabric of space squeezed and stretched and time.
Two L-shaped detectors in the Laser Interferometer Gravitational Wave Observatories (LIGO) in Louisiana and Washington collaborated on the very first observation of a gravitational wave. As the wave passed, each arm of the L-shaped detector, which is 2.5 miles long, lengthened and shortened by a distance of about one-thousandth of the diameter of a proton. To give a scale, this corresponds to the measurement of the distance from here to the nearest star system Alpha Centauri with an accuracy in the width of a human hair.
Well, with the help of another facility in Italy, Virgo, scientists are investigating the general characteristics of these collisions with the black hole and where they take place. Gravitational waves travel at the speed of light, and when they travel through the earth, there is a small delay between each detector. This delay is used to determine the location in the sky where the collision occurred. The technique is similar to the way geologists use earthquake arrival times on different seismographs to locate the origin of the earthquake.
With the detectors from LIGO and Virgo, scientists can better understand what happens when very heavy astronomical bodies collide. The collision of neutron stars, which are shells of stars that are slightly smaller than black holes, can also trigger gravitational waves that are detected on Earth. And of course, a black hole could also merge with a neutron star.
In a recent paper, gravitational-wave astronomers described eleven of these collisions, four of which had never been previously announced since the detectors began operation. Given the downtime, if the equipment was not operational, this would result in a fifteen-day check Recognition. In the most impressive example, two massive black holes fused into a hole about 80 times the size of the sun. It's the heaviest star hole ever seen.
For a fraction of a second, the collision released more energy than any light released by every star in the visible universe. That was a huge thing. And all happened in a galaxy 9 billion light-years away.
Prior to LIGO's first observation, scientists did not believe stars could form black holes with masses about 15 to 20 times heavier than the Sun. With just eleven observations, scientists were already forced to rethink their theories.
While the announcement of a supermassive black hole makes for a good headline, this recent work has a less stunning, but more scientifically meaningful effect. The observation of a thing can be a curiosity. But several incidents later, scientists can draw conclusions.
By combining the known capabilities of the detector with the observed locations and the detection rate, astronomers can tell how often they occur. While scientists work with a small sample size, today they estimate that in a space sphere between half a billion and a billion light-years, a black hole association is expected each year.
And the story is not finished yet. The detectors are offline at the moment and undergo upgrades to make them twice as far from Earth. In this way, they can examine an eight times larger volume than before. The days of gravitational wave astronomy are still in their infancy, and there are undoubtedly big surprises ahead.