Interesting facts about black holes.

What is black hole?

A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This compression can take place at the end of a star's life. Some black holes are a result of dying stars.

The existence of such objects was first suggested as far back as the late 1700s. However, it was Karl Schwarzschild (1873-1916), a German astronomer, who basically developed the modern idea for a black hole. Using Einstein’s theory of general relativity, Schwarzschild discovered that matter compressed to a point (now known as a singularity) would be enclosed by a spherical region of space from which nothing could escape. The limit of this region is called the event horizon, a name which signifies that it is impossible to observe any event taking place inside it (since information is unable to get out).

Structure.

• The Singularity: This is the region of the black hole where all the mass of the black hole has been compressed down to nearly zero volume. As a result the singularity has almost infinite density and creates an enormous gravitational force

• The Event Horizon: This is the "point of no return". Any object, even light, that is within this radius cannot escape the gravitational pull of the black hole

• The Schwarzschild Radius: It is the radius at which the escape velocity is equal to the speed of light.

• The Ergosphere: If the black hole is rotating, then as it spins, its mass causes the space time around the black hole to rotate as well. This region is called the ergosphere.

Types of black holes.

Black holes are completely characterised by only three parameters: mass, rotation and charge. There are fourth basic types of black holes:

1. Stellar black hole. It forms when a massive star runs out of nuclear fuel and collapses under its own weight (supernova).

2. Supermassive black hole. These holes hide in the cores of galaxies (including our own galaxy, the Milky Way). They have mass of millions of Suns. These supermassive black holes originate at the time of galaxy formation or formed when smaller black holes merge together. Because of their location in the centers of galaxies, close to many tightly packed stars and gas clouds, supermassive black holes continue to grow on a steady diet of matter.

3. An Intermediate-mass black hole. Mass of such hole varies from a few tens to a few millions of the mass of the Sun. It is not clear how such a black hole would form.

What happens when you fall into a black hole?

If you fall into a black hole, you’re doomed. Sure, once you fall in you can never get back out, but it turns out you’ll probably be dead before you get there. The gravity you feel from an object gets stronger the closer you get. As you approach a stellar-mass black hole feet-first, the force of gravity on your feet can be thousands of times stronger than the force on your head! This has the effect of stretching you. Scientists call this “spaghettification.” By the time you reach the black hole, you’ll be a thin stream of matter many miles long.

Interesting facts about black holes.

The massive gravitational influence of a black hole distorts space and time in the near neighborhood. The closer you get to a black hole, the slower time runs.

In most textbooks you will probably see black holes that look like funnels. This is because they are being illustrated from the perspective of gravity wells. In reality they are more like spheres.

Technically speaking, stars aren’t the only things that can become black holes. If your car keys were shrunk down to an infinitesimally small point and still retained all of their mass, their density would reach astronomical levels which would make the force of their gravity ridiculously strong.

According to theories, matter within a black hole is crushed to infinite density, and space and time cease to exist. When this happens, the laws of physics break down because it is not really humanly possible to conceive of anything with zero volume and infinite density.

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