BLACK HOLE

                       



 Black Hole is the most mysterious object in the universe. In 1969, an American scientist John wheeler at first used the word black holem. But the concept of Black Hole came around 200 years ago. At first John Michelle,a don of Cambridge University wrote a research paper in which he gave the concept of black hole in 1783. In 1916 Einstein gave the concept of black hole’s presence in the book of general theory of relativity. The main concept of the black hole is… when a star dies there are many possibilities and one of the possible states is black hole. To know the concept of black hole you need to know how a star is born. Stars are born from the Nebula or other gases mainly hydrogen gases reaction. In the Nebula there are full of dust and gases. There are mainly hydrogen gases 75% and Helium gases 25% and other gases in a low quantity and hydrogen and other gases come toward themselves for the gravitational force. I mean when they come closer to each other a star is born and as a result a huge temperature creates for the collision. And for the huge temperature the hydrogen atoms cannot stop themselves to collision with each other and as a result hydrogen transfer into Helium and slowly a star is born. When hydrogen transfer into Helium a huge quantity of temperature creates and it is like the temperature when hydrogen bomb blast. So now a question.. how does a star get stability? In the centre of the stars the hydrogen transform into Helium for nuclear fusion and many inter reaction happen in the centre. As a result, a huge quantity of temperature creates for this reaction and it also creates huge quantity of pressure. So when the gravitational force compress the stars then the pressure stop try to compression and it creates equality or stability. When the mass of a star increases, the gravitational force will increase. So to maintain stability it will need more pressure. So more hydrogen transfer into Helium and it will happen fastly. So the fuel and the other flammable things in the centre of the star will finished fastly. So what happened when the all will finish. It creates a great problem. The whole star will start shrinking into the centre for the huge Gravity. In this time there create many possibilities. An Indian scientist Chandrasekhar suggested a limit of mass which is called Chandrasekhar limit. It creates a big evolution in the field of Black Hole. The law explain that if the mass of any cold star is 1.5 times higher than the mass of the Sun, the star cannot save its life from the gravitational shrinking . What happens if the mass of a cold Star which is shrinking by the gravity, is lower than Chandrasekhar limit. It stops shrinking and at last it becomes white Dwarf which is thousands of miles in diameter and the density is about some tones per inch. Many white Dwarfs are discovered by astronomers. The white dwarf is supported the repulsion based on exclusion principle of electrons but another scientist Lev Lando attracted our attention on the possible state of dying star. It is a neutron star when the mass of a star is two times more than the mass of the Sun. Then the stars transform into a small stars which are smaller than the other stars and the diameter of the star is about nearly 10 Mile, but density is 10^17 kg /metre^3 .When the mass of the cold stars cross the Chandrasekhar limit,there create big problem. One problem is it creates a supernova explosion and the second problem is it wants to decrease its mass and want to make its mass below the Chandrasekhar limit and it tries to avoid catastrophic gravity collapse.
By the way when the mass of a cold star crosses the Chandrasekhar limit, it shrinks into the centre and creates a highly dense point. The gravitational force of the dense point is much much higher than anything and it curves the space time more than others. The dense point Is called black hole. The gravitational force of Black Hole is equal to the plank force/2. The plank force is 1.2×10^44 Newton. This force remains constant in black hole. The gravitational force is much higher than the light can not escape from this black hole. Everything which enters in the Event Horizon in the black hole, pulled into the black hole. Many matter and antimatter are created in the event horizon. They are called virtual particles. They collide with each other and destroy each other. It calls Quantum fluidization.The collision happen in the Event Horizon place. But for the huge gravitational force many times the matter and antimatter can not collide with each other, then the anti matter are attracted by the black hole and it enters in Black hole. But the matter can escape from the black hole. When it escapes from black hole like a radiation It calls Hawking radiation. In this way when black hole eats the antimatter, the mass of Black Hole start decreasing and by this way a black hole finish it's life.
The structure of Black Hole is described below…..
        1..Accretion disk
        2..Event horizon
        3..Singularity
        4..Photon sphere
        5..Innermost stable orbit

1..Accretion disk….. An accretion disk is a structure (often a circumstellar disk) formed by diffuse material in orbital motion around a massive central body. The central body is typically a star. Friction causes orbiting material in the disk to spiral inward towards the central body.

2.. Event Horizon.....The event horizon is the boundary defining the region of space around a black hole from which nothing (not even light) can escape. In other words, the escape velocity for an object within the event horizon exceeds the speed of light.

3.. Singularity...In the center of a black hole is a gravitational singularity, a one-dimensional point which contains a huge mass in an infinitely small space, where density and gravity become infinite and space-time curves infinitely, and where the laws of physics as we know them cease to operate.

4.. Photon sphere ...A photon sphere or photon circle is an area or region of space where gravity is so strong that photons are forced to travel in orbits. (It is sometimes called the last photon orbit.)

5..Innermost stable orbit..The Innermost stable circular orbit (often called the ISCO) is the smallest circular orbit in which a test particle can stably orbit a massive object in general relativity. The location of the ISCO, the ISCO-radius, depends on the angular momentum (spin) of the central object
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   Types of Black Hole
 So far, astronomers have identified three types of black holes: stellar black holes, supermassive black holes and intermediate black holes.


Why does time slow down near a black hole?

Black Hole Effects on Space and Time
From a distance, a black hole acts like any massive, gravitational object: Until it's right on top of you, it follows classical mechanics and Newton's law of universal gravitation, which tells us the attraction between two objects is proportional to their masses and drops off rapidly with distance. In other words, there's no gravitational difference between R136a1, a blue dwarf star weighing 265 suns, and a 265-solar-mass black hole [source: Fazekas].

Approach close enough for a black hole to wrap you in its gravitational sleeper hold, however, and you're grappling with a different set of rules: Einstein's general theory of relativity, which predicted black holes, says that gravity also warps space and time, and that extreme gravity does it, like Vanilla Ice, to the extreme.you wanted to study a black hole from a starship, you'd find that, the closer you got to the monstrous mass, the more oomph your engines would have to kick out to maintain a circular orbit. At first, firing off the occasional rocket burst would suffice to stabilize you; closer in, and you'd have to expend enormous energy just to maintain an irregular orbit. Closer still, and nonstop rocket burn would be all that stood between you and annihilation.

Once you ran out of fuel (or succumbed to space madness and turned off the engines), you would spiral in to the black hole's event horizon, a boundary beyond which nothing, not even light, can escape. From there, you'd have a date with destiny: Nothing you could do would stop your inexorable journey toward the singularity, a core of infinitely distorted space-time where physics as we know it curls up in a ball and whimpers.All through your approach, time would have slowed -- a lot. From your point of view, nothing would have changed but, to a friend watching from far away, time around you would flow less like greased lightning and more like sap on a cold February morning. Just outside the event horizon, you would appear to stop. Since light cannot escape the event horizon, that would be the last your friend would see of you.

Gravitational time warps occur universally but are usually too feeble to be noticed. On Earth, for example, you would age one-billionth of a second less each year at sea level than you would atop Mount Everest [source: Harvard-Smithsonian].

Within a black hole, time twists even more. In fact, when we say you can't avoid falling into the singularity, it isn't just because of the intense gravity or space warping: Rather, time within a black hole warps to such a degree that the singularity literally lies in your future. Trying to prevent reaching the singularity would be like attempting to halt time.

Read on to see what would happen if our solar system chanced upon such a flume of force.