Black Holes

index

1.Introduction to Black Holes

2.What are Black Holes?

3.How are Black Holes created?

4.Types of Black Holes

5.Parts of Black Holes

6.spaguettification

1.Introduction

The first time the idea of a black hole was suggested was in the late 1790´s by John Michell of England and Pierre-Simon Laplace of France. They both proposed the idea of the existence of an “invisible star” by applying the first Newton Law. They calculated its mass and size, which is now called the “event horizon” that an object would need in order to be faster than even the speed of light.Later, in 1915, Einstein predicted the existence of black holes with his general relativity theory. After that, in 1967, John Wheeler, an American theoretical physicist, applied the term of black holes to what it means now.

2.What are Black Holes?A black hole is a great amount of matter packed in a very small area. It is a place in space which has such a big gravitational field, that nothing, not even light can escape.

Scientists can’t directly observe black holes, and the only way to perceive them is by detecting their effect on other matter nearby. As the attracted matter accelerates & heats up, it emits x-rays that radiate into space, emitting powerful gamma rays bursts, which devour nearby stars.

3.HOW ARE BLACK HOLES CREATED

Stellar black holes: One way black holes are created is from dying stars. Inside a star, the nuclear fuel of a star and its own gravity collide. This creates stability, but when it runs out of nuclear fuel, gravity compresses the star. The outer layers explode into a supernova, and the centre implodes (collapses inwardly). After that, a black hole is created. This only occurs in big stars, which are at least 10 times bigger than the sun.

4.TYPES OF BLACK HOLEs

Miniature black holes: these type of black holes have event horizons as small as atomic particles. Physicists suggest that these were created during the Big Bang. Miniature black holes were created more than 10 billion years ago, and they compressed into a really small point, which later exploded and created a massive explosion.Supermassive black holes: fast-moving gas jets and gravitational forces are equal to 10 billion suns compressed together. These are what we call supermassive black holes. Their event horizon is an imaginary sphere around them which nothing can escape. When matter enters the black hole, it increases in size, reaching other matter which it could not absorb before.

ACCORDING TO ITS PHYSICAL

PROPERTIES:

The shwarzschild black hole, which has no charge, or rotation, the simplest type of black hole that exists.The Reissner-Nordstrom black hole, which does not rotate, but which has electrical charge.The Kerr-Newman black hole, which has charge and rotates.The Kerr black hole, which rotates and does not have charge inside.

WHITE HOLES and

WORMHOLESWhite holes are not proved to exist. A black hole is considered to be the exact opposite of a black hole. It cannot absorb matter, it can only expulse it. It is considered by some physicists to be the mathematical answer to the general equations of relativity.

If white holes actually existed, then, we would also see the appearance of a wormhole. A wormhole is the combination of a black hole and a wormhole. Wormholes would make matter enter through the black hole, and appear again through the white hole, because as they are too close to each other, spaguettification would not happen.

5.PARTS OF A BLACK HOLE:

The singularity: This is the part of a black hole in which all the mass of the black hole has been compressed to a very small space. As a result, the Singularity has almost infinite density.

The Event Horizon: This is the part of the black hole where nothing can get out. It is usually defined as a big sphere that surrounds the black hole, and which absorbs any material including light. Some theories say that only radiation can escape this area.

The Accretion Disk: This is a disk that is composed by stellar material, which goes around the black hole, forming a spiral

The Ergosphere: If a black hole is rotating, as it spins, its mass causes the space and time to rotate around it

The Photon Sphere: the photon sphere is a place in which gravity is so high that photons have to travel around the black holes´ orbit. It is the place in which light is forced to stay inside the black hole.

The Schwarzschild Radius: This is the event horizon´s radius. It is the radius at which the escape velocity is equal to the speed of light.Is the event’s horizon radius. Its formula is:

R=2GM/c2

Jets of Gas: In some black holes, there is such high intensity that magnetic fields are emitted perpendicular to the accretion disk. Due to this, some charged particles have to go around the black hole, because it is in a magnetic field

6.spaghettification

In Astrophysics, this term refers to the effect a black hole imposes on a body or matter. The term was proposed by Stephen Hawkins in his book “A Brief History of Time”, where he compared this effect to spaghettis, saying that you are stretched, and you turn so thin that you break apart, and transform into matter.

Curious facts about black holes

1.They can explote (only the smaller ones)

2.They fire Intergalactic Death Rays

3.It is not their mass, it is their size what matters

4.Black holes disort Space-Time

5.Objects appear to ‘freeze’ near a black hole

6.Black eventually evaporate over time

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