Where Super Massive Blackholes Live - Space's Deepest Secrets - Science Channel

At the very heart of every large galaxy lurks a monster. A supermassive black hole. These are the undisputed heavyweight champions of the cosmos. There's a trillion galaxies in the observable universe and each one has a supermassive black hole in its center. Supermassive black holes can weigh as much as 6 billion suns and all that matter is packed into a tiny point in space. They'll suck in anything that strays too close. Planets, stars, not even light can escape. A black hole is a bottomless pit of gravity that actually draws in material all around it. If you get too close, there is no force in the universe that you can apply to yourself to get back out. But as well as being the ultimate agents of destruction, supermassive black holes bring order to the universe. Their colossal gravity corrals countless stars into orbit around them, forming the hearts of galaxies. We think that the galaxy itself depends on that supermassive black hole for its structure. If these things didn't exist, galaxies would look completely different. But a big mystery surrounds supermassive black holes. We have no idea where they came from. How does the universe compress the mass of 6 billion stars into a single point in space? The answer won't just tell us how supermassive black holes form, it may reveal how the galaxies that fill the universe came to exist too. If we can understand how supermassive black holes grow, then that's kind of like the holy grail of understanding how galaxies evolve. Maybe the answer to how supermassive black holes formed can be found in the life and death of other black holes. Because we've long known that supermassive black holes have a tiny relative, stellar black holes. And unlike their supermassive cousins, we do know how these tiny stellar black holes form. Stellar mass black holes form when a massive star dies. The core collapses into this super dense object that we call a black hole. The core might have three or five or ten times the mass of the sun, and that's why they are stellar mass black holes. They have about the mass of a star. When a huge star dies in a dramatic supernova explosion, all that's left is the dense remnant of the star's core, crammed into a minuscule point in space, a stellar black hole. Imagine that a star like the sun can shrink down to essentially a pinhead size. It sounds wild and crazy and like science fiction, but it's science reality. If collapsing stars form stellar black holes, could their supermassive cousins have formed this way too? It's a neat idea, but there's a problem. Stellar black holes may weigh in at several times the mass of our sun, but they're a million times smaller. That means they're dwarfed by the monstrous supermassive black holes. Supermassive black holes can be as big as an entire solar system. No single star could ever be big enough to collapse into a monster black hole this size. The challenge for scientists is to figure out how the universe created black holes that are billions of times more massive than the sun. One theory is that perhaps supermassive black holes weren't born big. Instead, they may have grown from smaller black holes merging with each other. Theorists have long predicted that black holes should be able to merge, but astronomers need observations to prove it's true. In the heart of the idyllic Italian countryside sits a machine designed to detect the far-off murmurs of black holes merging. This is Virgo. Here, scientists monitor the cosmos 24-7, hunting for black holes. Walter Del Ponzo is a theorist on the team. What I do is trying to understand what black holes are, and how they work, and how they grow, how they evolve. I love the challenge of trying to understand how the universe works. Walter wants to use Virgo to do something that was once thought impossible. He hopes to detect black holes growing. Walter believes that if one black hole merges with another, the violence of this event should send telltale ripples out through the fabric of space. Just like the ripples in a pond. Physicists call these ripples gravitational waves. It was once thought that they'd be too small to detect, but then machines like Virgo came along. Virgo consists of not one, but two two-mile-long pipes forming an L-shape. These pipes are the most sensitive measuring devices on Earth. A laser is shot along these two right-angle lines. They travel all the way to the end. They bounce on a mirror. They come back. This makes these two arms a very, very, very sensitive ruler, which we can use to detect tiny changes in the distances. If a gravitational wave from merging black holes passes through Virgo's two pipes, it could compress and expand first one pipe, then the other. Changes in length Walter hopes to measure. Those changes are really, really tiny. This is why we need those huge, huge rulers to be able to detect those tiny, tiny, tiny changes. These lasers can detect these two-mile-long pipes changing length by a billionth of the width of a human hair. And in August 2017, these super sensitive instruments allow Walter and the team to witness something extraordinary. They detect the unmistakable ripple of two black holes merging. Virgo has been a great success indeed. What we are seeing here is the deadly dance of two black holes. They get closer and closer. And from here, we can actually tell that the final object was a black hole. This whole process that we registered lasted a fraction of a second. Walter's reading is the ripple of an event that took place one billion years ago. In a distant galaxy, two black holes approach each other. One 25 times more massive than our sun. The other 30. They enter into a death spiral. The two black holes accelerate to almost half the speed of light. Until finally, they collide, leaving behind a single much heavier black hole. It takes a billion years for the ripples from this black hole merger to reach the Virgo detector on Earth. This is a major breakthrough. Virgo and similar machines in the U.S. have finally proven that black holes can grow by merging together. We were the first ones in history to be able to see two black holes eating each other and merging to become a single black hole. That's incredible. And by measuring gravitational waves, astronomers get their first taste of an immensely powerful new tool for understanding the cosmos. Now we have a fundamentally new window in the universe. That's not collecting light. That's listening to the music of the cosmos. And it is an absolutely transformational new way to look at the universe. So, is it case closed? Do smaller stellar black holes merge together to form supermassive black holes? Unfortunately, it seems unlikely. And if not, then how did supermassive black holes grow so big? Scientists might be on the verge of an answer.