Black holes :
They are the most fascinating objects in the universe. They are considered to be the end of the Universe. They absorb anything which is near them.
Formation of Black holes :
Consider an object in the universe. According to Newtons universal law of gravitation every object in the Universe posses gravity and that gravity depends upon the mass of the object. Imagine the mass of the star which is very hugh in size. The star posses very high gravitational power. This gravity collapses the star wheras the nuclear reactions in that star tries to create a super nuclear explosion. In a star, these forces balance each other and the ratio of the magnitude of the forces determine the size of that star.
When a star dies, the nuclear reactions stop and nuclear forces vanish,wheras the gravitational forces collapse the whole star into its core of enormous density. At this time, the star explodes causing a supernova explosion. This explosion throws matter out into space. When small stars explode they produce supernovas. But according to Subramanya Chandrasekhar, hugh stars with mass 1.4 times greater than solar mass collapse into an object of enormous density. Thus in case of hugh stars the remaining matter after the supernova explosion collapse into the tiny core with enormous density and gravity. This core is called a Black hole. It literally disappears from view. The core sinks in space time creating a hole in space time and hence it is called a black hole.
Its gravity is so strong that even light cannot escape. The escape velocity is greater than the speed of light. When an object is compressed to such a small extent, the escape velocity becomes greater than the speed of light. A black hole can absorb anything. They can even absorb a galaxy if they have enough power. Black holes also emit jets. When an object gets into a black hole all events and points in space time stop for that object.
Structure of a black hole :
A black hole, although invisible has properties like mass, electric charge and density. There are two types of black holes. They are rotating black holes and non rotating black holes. Rotating black holes are the most common in the Universe. They are formed from stars which were rotating once. They are formed as rotating black holes such that they conserve angular momentum.
A rotating black hole consist of a singularity( the center), Ergosphere, static limit,event horizon. Objects entering the ergosphere can eject from the black hole by gaining energy from the rotation of the black hole. But still if the object crosses the event horizon there is no escape for that object.
Detection of Black holes :
Though black holes are invisible we can detect them. Black holes posses hugh mass and that mass causes the high gravity. We can detect the black hole and determine the mass of it by looking the objects around it. For example a star near by has a wobbling motion and that motion has an unknown reason we may suggest a black hole nearby. The mass of the black hole can be found using newton's third law of planetary motion.
Next is the gravitational lens, Einstein predicted that gravity could bend space. It was observed when during a solar eclipse a planet was appearing shifted due to gravity. When a star was observed it appeared in a double way and an object inside was invisible so we can suggest that a black hole has passed by in between.
Black holes also emit jets, these jets travel thousands of light years away from galaxies. Only supermassive black holes are believed to emit jets. Even in our galaxy milky way a black hole was observed emitting massive jets.
When two black holes come nearby they form a wormhole in between. All sayings like "when we enter a wormhole we would go to another universe and we can gain immortality" are false and they are human beings imagination. When an object gets into an accretion disk it gets heated to millions of kelvin and emit X-rays. It gets absorbed into the singularity.
Black holes are objects of great importance ever since they were predicted by Albert Einstein. Moreover they do not consume everything. Really these are fascinating objects in space.
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