Black+holes

What is a black hole?
Black hole is a region in outer space from which nothing can pass through, including light. Around it lies an invisible area that marks the point whereby you can not possibly turn back anymore and escape from the black hole, called the event horizon, further explained below. It is the result of the spacetime being deformed, caused by a very compact mass, like after a supernova by a big star. It can be observed too despite it having an invisible interior, by observing the behaviour of the other matters surrounding it. In this article, I will explain to you the main two parts.

By the way, do you know that there is a theorized total opposite of black holes? They are known as the "white holes"! Check them out here.

The Event Horizon
It is a boundary of spacetime through which matter and light can only move towards the center of the black hole. The closer the object is to the event horizon, the more distorted the spacetime is. Not even light can escape from the event horizon. Thus, if for instance, person A is getting sucked into the event horizon, person B would see person A move slower and slower towards the event horizon, and possibly taking infinite amount of time to reach the center, as when it gets closer towards the event horizon, lesser light would reflect back to person A's eyes, until when person A is almost sucked into the event horizon, person A would be dim to person B, and finally disappear from person B's sight. Also, if something happens in the event horizon, or an event occurs, there would be no way to determine that it happened, as the spacetime direction is only facing the black hole now, thus the name "Event horizon".

Pictures courtesy of Wikipedia.

Far away from the black hole a particle can move in any direction. It is only restricted by the speed of light. || Closer to the black hole spacetime starts to deform. There are more paths going towards the black hole than paths moving away. || Inside of the event horizon all paths bring the particle closer to the center of the black hole. It is no longer possible for the particle to escape. ||
 * [[image:http://upload.wikimedia.org/wikipedia/commons/thumb/5/55/BH-no-escape-1.svg/409px-BH-no-escape-1.svg.png width="409" height="106" caption="Image:BH-no-escape-1.svg" link="http://en.wikipedia.org/wiki/File:BH-no-escape-1.svg"]]
 * [[image:http://upload.wikimedia.org/wikipedia/commons/thumb/1/10/BH-no-escape-2.svg/409px-BH-no-escape-2.svg.png width="409" height="106" caption="Image:BH-no-escape-2.svg" link="http://en.wikipedia.org/wiki/File:BH-no-escape-2.svg"]]
 * [[image:http://upload.wikimedia.org/wikipedia/commons/thumb/8/87/BH-no-escape-3.svg/409px-BH-no-escape-3.svg.png width="409" height="106" caption="Image:BH-no-escape-3.svg" link="http://en.wikipedia.org/wiki/File:BH-no-escape-3.svg"]]

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The reason for its distortion of spacetime is due to its large mass. Imagine the spacetime as a piece of fabric, and the black hole, or the large mass is a very heavy ball. At first, the fabric would be straight and flattened. Then, when the ball is placed on the fabric, the ball causes the parts of fabric surrounding the ball to curve in. This represents the deformation and distortion of spacetime by the blackhole. Thus, as the curve gets steeper and steeper, it would get harder and harder to let maybe another ball (particle) roll back to another position.but to roll into the curve of the big ball. =====

The Singularity
The singularity, or or rather the gravitational singularity is a region where the spacetime curvature becomes infinite. It has zero volume, but it can also be shown that it contains all the mass of the black hole, thus having infinite density.

Anyone that falls into a non-rotating black hole cannot avoid it, and any attempts is futile, as it only will shorten the time to get there. They will get torn apart too before reaching the singularity, where they will be crushed to infinite density and their mass will be added to the total of the black hole. However, it is possible to avoid the singularity for the case of a rotating black hole in a complex manner whereby one exit the blackhole into a different spacetime, with the black hole acting as a worm hole (something that can be said to act as a shortcut for long distances, faster than the shortest path we learnt in maths, geometry, whereby the shortest path is a straight line.)

Conclusion
So far, we learnt about the black hole. To sum it up, look at the illustration (Drawn by me) below.

The white circle in the middle is the singularity, and the surrounding parts (Those that looks "curved in") are the event horizon. This is just a 2D top view of the spacetime
with the black hole. Note that all these should be invisible and there would be things sucked into it.

Source(s):

 * Wikipedia

Final note: This is NOT copy and pasted.

Reflection:
I chose to do this article on black holes, as I was interested on it at first, and decided to look up on it further, thus ending up with this article. Also, since this is supposed to be original work, I decided to add a drawing of mine. It was a tough process indeed to draw out the picture! I had to spend quite some time lengthening some lines, since the original method of drawing would end up with a square, and I learnt how to draw this from a (currently) Secondary 3 student. In all, it was a refreshing process and I learnt new things in the process, like what are black holes, and its features, whereby at first I thought it was just a black empty space.