Black holes
The universe is full of wonders, from dwarf planets and mesmerising hidden galaxies to, obviously, black holes! You are right to consider these mysterious objects as holes that you see on Earth, for they suck everything up around it! Let's dive in deeper to learn more!
What are black holes?
Simply put, you can take them as dents in the fabric of space (space in the universe) which has so high a gravitational pull, any nearby object gets sucked into it! No object has ever escaped the pull of black holes in history. The reason it has such a high gravitational pull, is because it is extremely dense, with a lot of matter squeezed into it. To escape it, an object has to have an extremely high escape velocity. Escape velocity is the speed needed for an object to just exactly escape the gravity of a planet. Black holes are massive and so dense, that no matter has sufficient escape velocity to not get sucked in by it. No, not even light, the fastest in the whole universe! This is the reason we cannot see black holes- no light escapes from it to enter our eyes and form an image. A simple physics rule:D
Of course, black holes cannot only be gigantic and hulking. They come in all masses and sizes. Scientists guess that the smallest ones are the size of an atom, whereas bigger ones (called "stellar") can be 10-20 times the mass of the Sun. In the Milky Way (Earth's galaxy), there are a lot of stellar black holes. Even so, because the size of something does not determine its mass, as the small ones can be as heavy as a mountain too. The largest black holes (called "supermassive"), with humongous masses that are more than the mass of 1 million Suns combined together! There is no limit to how heavy a black hole can be. In the centre of every galaxy, a supermassive black hole is found. The one in our galaxy is called Sagittarius A- as heavy as 4 million Suns, and can contain a few million Earths. Amazing!
Simply put, you can take them as dents in the fabric of space (space in the universe) which has so high a gravitational pull, any nearby object gets sucked into it! No object has ever escaped the pull of black holes in history. The reason it has such a high gravitational pull, is because it is extremely dense, with a lot of matter squeezed into it. To escape it, an object has to have an extremely high escape velocity. Escape velocity is the speed needed for an object to just exactly escape the gravity of a planet. Black holes are massive and so dense, that no matter has sufficient escape velocity to not get sucked in by it. No, not even light, the fastest in the whole universe! This is the reason we cannot see black holes- no light escapes from it to enter our eyes and form an image. A simple physics rule:D
Of course, black holes cannot only be gigantic and hulking. They come in all masses and sizes. Scientists guess that the smallest ones are the size of an atom, whereas bigger ones (called "stellar") can be 10-20 times the mass of the Sun. In the Milky Way (Earth's galaxy), there are a lot of stellar black holes. Even so, because the size of something does not determine its mass, as the small ones can be as heavy as a mountain too. The largest black holes (called "supermassive"), with humongous masses that are more than the mass of 1 million Suns combined together! There is no limit to how heavy a black hole can be. In the centre of every galaxy, a supermassive black hole is found. The one in our galaxy is called Sagittarius A- as heavy as 4 million Suns, and can contain a few million Earths. Amazing!
How are they formed?
It is believed that the smallest black holes started to form billions of years ago, when the Universe first came to life. Stephen Hawking, considered to be the best physicist in the world today, proposed the idea that trillions of mini (non-stellar) black holes were created during that time. But generally, stellar black holes are formed when stars "die"; or more specifically, collapse upon themselves. A supernova surfaces, and the core of the star caves in and implodes after being unable to balance its internal pressure with its own gravitational force. The radius of the star shrinks to a critical size, called Schwarzchild radius, and there arises a black hole.
So, if you can infer, scientists can figure out where black holes are forming when stars die, and thus, we know where black holes might be without being able to see them. Another guess is to identify a large, dark mass concentrated in a small volume, which probably means it is a black hole. Scientists can also study the relationship between stars orbiting black holes. If they find that stars are orbiting around something very dark, they can use satellites and telescopes in space to see a high-energy light (emitted when black holes and stars are close together). These are just some ways of searching for black holes.
So, if you can infer, scientists can figure out where black holes are forming when stars die, and thus, we know where black holes might be without being able to see them. Another guess is to identify a large, dark mass concentrated in a small volume, which probably means it is a black hole. Scientists can also study the relationship between stars orbiting black holes. If they find that stars are orbiting around something very dark, they can use satellites and telescopes in space to see a high-energy light (emitted when black holes and stars are close together). These are just some ways of searching for black holes.
What happens if someone falls into a black hole?
Hopefully it would not happen, because if it did, only one word would describe the person in the end- ripped apart. At first, further away from the centre of the black hole, he would feel weightless, with no gravitational pull, as if he was in free fall. However, later, he would start to feel stretched as the gravitational forces increase as he moves closer to the centre. Eventually, he would be ripped apart. It is good to note that he does not see anything special, only distorted images of space outside, as light bends as it still reaches his eyes. However, no one on the outside can see him, for no light escapes from the black hole sucking him in! This would be pretty scary.
Hopefully it would not happen, because if it did, only one word would describe the person in the end- ripped apart. At first, further away from the centre of the black hole, he would feel weightless, with no gravitational pull, as if he was in free fall. However, later, he would start to feel stretched as the gravitational forces increase as he moves closer to the centre. Eventually, he would be ripped apart. It is good to note that he does not see anything special, only distorted images of space outside, as light bends as it still reaches his eyes. However, no one on the outside can see him, for no light escapes from the black hole sucking him in! This would be pretty scary.
Black holes are very strange things that have intriguiged scientists for many years; and will continue to for time to come. I feel that the Universe if full of weird and unimaginable things. Black holes are only one in a million. Scientists are dedicating their time and effort to learn more about these things so that we can learn more about the Universe, which is reputed to be our origin. What will happen when we uncover its mysteries, I dare not dream of. I personally feel that the Universe's secrets can never be fully revealed. Nevertheless, it is always good to gain more knowledge about the things around us, which is a quality all students of science must have. I look forward to surprises about the Universe in future, and they may be even more amazing discoveries too!
Watch this animation below to for a little fun about black holes
Watch this animation below to for a little fun about black holes