Two black holes are on a collision course and the collision will take place in the next three years.
It could go down in history as one of the great modern astronomical events
Two black holes are on a collision course and the collision will take place in the next three years. On a cosmic scale, three years means imminent. The collision could go down in history as one of the great modern astronomical events.
It is not the first time that this colossal phenomenon has occurred, nor is it the first time that we can observe it. It happened in 2016, but it caught us a bit by surprise. On that occasion, the LIGO , Virgo and GEO600 observatories announced the first detection of gravitational waves produced by the merger of two black holes.
This time, however, experts from all over the planet will be attentively observing to capture live the shock of the collision of two black holes in all its splendor.
The singularity of a black hole
We owe to an English clergyman, John Michell, at the end of the 18th century, the concept of a black hole as a body of such mass that light cannot escape from it. John Michell’s idea was left in the background since at that time it was beginning to be thought that light was a wave and not a particle, so, since it had no mass, gravity should not affect it. Two centuries later, at the beginning of the 20th century, Albert Einstein recovered this theory arguing that light sometimes behaved like a wave and other times like a particle, postulating the wave-particle duality of light, which turned out to be true.
Ten years later, in 1915, Albert Einstein himself published his Theory of General Relativity and showed that light was affected by gravity, curving its path in space-time as it passed near massive objects. Light really always travels in a straight line ( geodesic ) but straight lines in the vicinity of a massive object, like a black hole, are not what we think.
They do not emit light but can be seen
Thus, we are facing a finite region of space whose mass density is so high that it generates a gravitational attraction from which not even light can escape, being attracted and falling hopelessly into the gravitational singularity .
But, if not even light can escape from them, how can we see them ?
There are at least two ways to observe black holes. First of all, we can know the effect that its gravity has on the objects around it. For example, in the center of the Milky Way there is a dark spot around which millions of stars orbit. This dark dot is a black hole, Sagittarius A* .
In fact, with great probability, at the center of most galaxies there is a black hole.
Observe the matter that falls inside
We can also observe matter falling into a black hole. As matter approaches, what is called an accretion disk is generated , made up of dust and gas that revolves around the black hole and eventually tends to fall into it.
This disk of matter is accelerated so much that the radiation it emits is in the range of X-rays, which we can observe with the appropriate instruments.
In the famous image of the Gargantua black hole that appears in the movie Interstellar or in the first real image of a black hole, obtained thanks to the collaboration of more than 200 researchers from around the world (15 Spanish), led by Katie Bouman , what what is observed precisely is the accretion disk .
The two black holes about to collide are in the SDSS J1430+2303 galaxy, located 1 billion light-years from Earth.
The fluctuations that astronomers have detected in the center of SDSS J1430+2303 suggest that two supermassive black holes located inside it will collide within the next 3 years.
The collision really happened 1 billion years ago, but its effect and therefore the possibility of observing it will now reach us on Earth.
The merger of these black holes, with a mass equivalent to 200 million suns, will make it possible to study the formation of new cosmic structures and how the holes increase in size, among other phenomena
The space-time will tremble a little
At the moment in which both black holes come into contact and merge, various phenomena will occur. First of all, the space-time around it will be shaken generating gravitational waves , as if we were throwing a stone into a pond in which ripples are generated on the water.
Gravitational waves will travel in all directions in space at the speed of light, so we will be able to observe any light effects that take place during the merger of the two colossi, while detecting gravitational waves.
Researchers and scientists from around the world already have telescopes and interferometers ready to capture the event. The shock will not affect our daily lives but it will once again put Einstein’s equations of General Relativity to the test and may reveal hitherto unknown aspects of the cosmos and its inhabitants.
This will be the first time that humanity will be able to see the collision of two black holes live. The scheduled date: the year 2023. We will feel the jolt in space-time.
Francisco José Torcal Milla , Professor of the Department of Applied Physics, University of Zaragoza
This article was originally published on The Conversation . Read the original .