Black Holes

   Black holes are the obviously, one of the most fascinating object of the Universe. The gravitational attraction within a black hole is so high that anything which goes into it cannot escape. Even light cannot escape the gravitational pull of a black hole.

      As far as the formation of a black hole is concerned, consider a star whose original mass is five times more than that of the sun. Then, after supernova explosion, the core continues suffering compression indefinitely due to recoil. This result into black hole.

       
    If ‘M’ is the original mass of the star, than its radius is given by-

             r = 2GM/c²     where ‘c’ is the velocity of light.

   And escape velocity for an object on its surface is given by –

             v = √2gr         where ‘g’ is the acceleration due to gravity on its surface

The escape velocity for such a black hole is equal to or greater than the speed of light.

Now according to the special theory of relativity, it is not possible to achieve a velocity greater than ‘c’ for the material object. Thus nothing can escape from a black hole.