16/04/2024
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What is a Black Hole ?

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What is a Black Hole ?. Understanding Black Holes

What is a Black Hole ?. Black Holes are 1 of the weirdest things in existence. They don’t make any sense at all. Where do they come from & what happens if you fall into 1 ?. Stars are incredibly huge collections of mostly hydrogen atoms that crumble from enormous gas clouds under their gravity. Nuclear fusion crushes hydrogen atoms into helium in their core. Thus releasing a tremendous amount of energy. This energy is in the form of radiation pushes against gravity maintaining a fine balance between the 2 forces. As long as there’s fusion in the core, a star remains stable enough. But for stars with way more mass than our own Sun, the heat & pressure at the core allow them to fuse heavier elements until they reach iron.

Unlike all the elements that went before the fusion process that produces iron doesn’t generate any energy. Iron builds up at the core of the star till it reaches a critical amount & the balance between radiation & gravity is broken all of a sudden. The core collapses. The star collapses within a fraction of a second. Traveling at about a quarter of the speed of light, feeding even more mass into the core. At this very moment that all the heavier elements in the universe are born as the star dies, in a massive supernova explosion. This creates either a neutron star or if the star is gigantic enough, the entire mass of the core collapses into a Black Hole.

What is a Black Hole & the Event Horizon ?

If you looked at a Black Hole, then you would see the event horizon. Anything that surpasses the event horizon needs to be traveling faster than the speed of light to getaway. But, it’s impossible. So we just see a black sphere that reflects nothing. But if the event horizon is the black part, what’s the “hole” part of the black hole ?. The singularity. We’re not sure what it’s exactly. A singularity may be ceaselessly dense, meaning all its mass is concentrated into a single point in space with no surface or volume or something completely dissimilar. Right now, we just don’t know. It’s like a “dividing by zero” error. Black holes do not suck things up like a vacuum cleaner. If we were to swap the Sun for an equally gigantic Black Hole then the Earth will not change much but we would freeze to death.

Do you know what would happen to you if you fell into a Black Hole ?. The experience of time is dissimilar around Black Holes. From the exterior, you seem to slow down as you approach the event horizon. So time passes slower for you. At some point, you would appear to freeze in time, slowly turn red & disappear. While from your standpoint, you can watch the rest of the universe in fast-forward way of like seeing into the future. Right now, we’re clueless about what happens next. But we think it could be 1 of 2 things.

Black Holes & its probabilities

1, you die a quick death. A Black Hole curved space so much that once you cross the event horizon, there’s only 1 possible direction. You can take this inside the event horizon. You can only go in 1 direction. It’s like moving in a tight alley that closes behind you after each step you take. The mass of a Black Hole is extremely intense. At some point, even tiny distances of a few centimeters would mean that gravity acts with zillions of times more force on all parts of your body. Your cells get ripped apart, as your body stretches more & more until you’re a scorching stream of plasma, 1 atom wide.

2, you die a very quick death. Soon after you surpass the event horizon, you would hit a firewall & be terminated in an instant. Neither of these options is particularly pleasant. How fast you would die depends on the size of the Black Hole. A smaller Black Hole would crush you before you even entered its event horizon. While you probably could travel inside a supermassive black hole for some time. As a rule of thumb, the further away from the singularity you’re, the longer you live. Black Holes come in different sizes. There are stellar-mass Black Holes, with a few times the mass of the Sun & the diameter of an asteroid. Then there are these supermassive black holes, which are found at the heart of every galaxy & have been feeding for billions of years.

The death of a Black Hole

Currently, the largest Supermassive Black Hole known is S5 0014+81. It’s enormous & 40 billion times compared to the mass of our Sun. Its diameter is 236.7 billion kilometers. It’s 47 times the distance from the Sun to Pluto. As powerful as Black Holes are, they’ll eventually evaporate through a process called Hawking radiation. We’ve to look at empty space to understand how this works. Empty space is not empty but filled with virtual particles popping into existence & annihilating each other again. When this happens right on the edge of a Black Hole, 1 of the virtual particles will be drawn into the Black Hole & the other will escape & become a real particle. Thus the Black Hole is losing energy slowly.

This happens incredibly slowly at 1st & gets faster as the black hole becomes smaller. It radiates at room temperature when it comes to the mass of a massive asteroid. It starts radiating with about the heat of our Sun when it has the mass of a mountain. The Black Hole radiates away with the energy of trillions of nuclear bombs in a huge explosion in the last few seconds of its life. This process is incredibly slow. The biggest black holes we know can take up to a googol year to evaporate. This is so long that when the last black hole radiates away, nobody will be there to see it. Then the universe will be uninhabitable long before then.


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