Two black holes billions of light-years away are about to slam into each other, and it could gives us a front-row seat to an incredible event.
The scientific world is abuzz with news that two supermassive black holes that are circling each other and will collide in slow motion, releasing extraordinary amounts of energy, as we reported recently — but just what happens in this mysterious effect and how it does it affect the space-time fabric?
Scientists have spotted two black holes in the Virgo constellation billions of light-years away, spotting two quasars close to each other that seem to indicate the presence of two black holes circling each other at just a light-week apart, less than the size of our Solar System.
It’s not the first time supermassive black holes have collided in our universe’s history, but rarely has mankind been able to witness it about to happen. Most of the time scientists can only view the after-effects.
First, to understand what is really going on, you have to understand that supermassive black holes are often found at the center of galaxies — almost always, in fact. So when you see two supermassive black holes combining, you’re seeing two galaxies colliding and merging with each other, a tremendous cosmic event that is difficult for us to even comprehend.
The two black holes in particular are well within the galaxy merging process, circling each other at a very close distance, and after a period of time they will collide with each other, release a vast amount of energy and sending ripples through the space-time fabric.
Before this most recent discovery, the closest black hole pair was still 20 light years apart.
By this time, both black holes have entered the point of no return — there is no chance they escape each other’s gravity. No force exists that could possible separate them, and so it is inevitable they will collide to form a bigger black hole.
It’s an extremely violent event, and it’s a good thing we’re nowhere near it when it happens — in fact, since we’re viewing black holes that are billions of light-years away, this event already happened in our distance past, and we are only just witnessing it now.
Scientists don’t have a lot of answers on what happens when two black holes collide, other than that they form a new, larger black hole. After all, we’ve never actually witnessed one, and it certainly would not be possible to do anything but observe one at a great distance with a very powerful telescope.
However, we do know that the surface area of the new black hole will be at least the surface area of those two black holes added together. A law of black hole thermodynamics is that the total surface area of black holes can only increase.
So what exactly is a black hole anyway? Essentially, it’s a geometrically defined region of space-time that exhibits incredible gravitational effects — so great that nothing can escape its pull, not even light.
General relativity holds that a mass that is compact enough can cause space-time to be deformed to the point that it can collapse into a black hole.
Black holes are often formed when massive stars collapse at the end of a life cycle. This black hole can continue to grow as the mass of other stars and other black holes feeds it to become a behemoth, often known as a supermassive black hole. These are usually found at the center of galaxies, the center around which all of the untold amount of stars in the galaxy circle, so great is the gravity of this black hole.
It’s difficult to observe a black hole directly because it is invisible as it gives off no light, so scientists must observe it by how it interacts with other matter and visible light. An accretion disk can be formed when matter falls into a black hole, and it can be blasted out into space in the form of a quasar, which is one of the brightest known objects in the universe. Scientists can use stars orbiting the black hole to come up with some estimates on where it is located and what its mass is.
At the center of a black hole there is something called a gravitational singularity, which is where the space-time curvature suddenly becomes infinite. This single point can be described as having infinite density. Once anything is caught in the event horizon, it cannot escape being dragged into the singularity. It is then crushed into infinite density, and the mass is added to the total mass of the black hole. The immense power of the gravity will stretch out or tear apart anything that reaches this point, which is often called “spaghettification.”
Black holes have entranced the scientific community for decades. They are fundamental to understanding the laws of physics, and the difficult of observing these bodies makes them all the more mysterious.
The popular film “Interstellar” dove into the subject of both space travel and black holes. The film was a hit, grossing nearly $700 million, showing how interested the public was in such scientific questions.