The Black Hole theory

For the subject of my portfolio, I have decided to do on «Black Hole». I think that it can be very interesting because this incredible space object is very different from a lot of others space object. But before, I’ll tell you wath a black hole, his history and why is one of the must mysterious think, his incredible proprieties.

What’s a black hole? A black hole is a space object that sucks anything that pass near him, the light also can be sucks despite that speed of light is 3X108 m/s. The story of black hole begin in 17/18th century, all begin with the question to know if the light have a weight so if light can be influenced by the gravity like a particle. During the 17th century, for Sire Isaac Newton, the light is a corpuscular, like small ball of light but for Huygens, the light is a wave without weight. The finiteness of the speed of light being known, as well as the notion of speed of release, in the the case of a corpuscular light, possibly endowed with a mass, it is necessary to design a body so massive that the speed of release greater than the speed of light.

In this context, black hole can be considered as a typical example of paradoxe where a theorie push to its limit. In 1783, reverend John Michell, geologist and amateur astronomers expose an article send to the Royal Society tha concept of body so massive that even the light could not escape it, he write this : «If the half-diameter of a sphere of the same density as the sun and wich exceed that of the sun by a proportion of 500 to 1, a body falling from a infinite height to it would have acquired on its surface a speed greater than the light. Consequently, supposing that the light is attracted by the same force in proportiuon to its mass of inertia like others body, any light emitted from this body would return on itself by its own gravity».

It was not until that the marquis Pierre Simon de la Place, a mathématicien, philosopher and astronomer fascinated by celestial mechanics. He wrote in is book «Exposition du système du monde» : «a luminous star, of the same density as the earth, and whose diameter would be 250 times greater than the sun, would not allow by virtue of

its attraction, any of its therefore possible that the greatest luminous bodies of the universe could, because of this, be invisible».

The physicists remain skeptical of this thesis and the black hole falls in the dark for over century. He comes back in the twenthieth century, when Robert Einstein published his theorie of relativity. In 1915, He published his work on the general relativity, in this new theory, gravitation is identified with properties of space, the structure of which is modified by the presence of matter. Space is no longer an absolute entity, but a flexible structure deformed by the matter. The passage of time is also affected by the presence of matter. At the end of 1920’s, the Indian physicist Subrahmannyan Chandrasekhar show the beyond a certain mass an astrophysical object wich is not the seat of nuclear reaction collase upon itself under the effect of it’s own gravity.

Here was a little history course of the black hole. Now I’ll talk about some property for the less mysterious. First, like I say up, the light can’t quit the black hole, but do you know why is this object call «Black Hole»? It is name like that beceause you can’t see a black hole with any telescope (of course the light can’t leave this hole so he don’t have any colours and black hole are also dark that space), So how can you see that there is a black hole? You can easily note its effect. But with news technologie, recently researcher did the first photo of a black hole, it was on 10 april 2019. He still remains of great mistery, the centre of a black hole can not be discribe precislely because of the gravitionnal singularity, the centre can only be describe by a theory of quantic gravitation but this theory doesn’t exist yet.

Black hole depends only three parameter: the weight, electrical charge and cinetics moment to compare, a planet depends on more than hundred parameters. There is different type of black hole based on both parameter, the electrical charge and the cinetics moments (the weight is not taken into account that the mass is always above the zero for any object). He each has a different name depending on the combinaition of the two parameters, if the electric charge and the cinetics moments equal zero he is name black hole «Schwarzschild», if the electric charge and the cinetics moments are different from zero, it’s a Kerr-Newman, if the electric charge is different from zero but the cinetics moments equal zero, it’s a Reisnerr-Nordströrm, and last type, if the electric charge equal zero but not the cinetics moments, it’s a Kerr.

In addition to it’s type there, there are others, stellar black hole, supermassive black hole, intermediate black hole and the primordial black hole. The stellar black hole have a mass of at least three solar masses. They are born as a result of gravitational collapse of the massive stars.  Supermassive black holes have a mass of between a few million and a few billion solar masses. They are in the center of the galaxies and their presence sometimes cause jets of X radiation. Their centre is brighter than stars. Intermediate black holes are newly discoverd objects and have a mass between 100 and 10 000 solar masses. The primordial black holes, also called micro black hole or quantum black hole, they would have formed during the Big Bang.