http://hubblesite.org/reference_desk/faq/answer.php.id=56&cat=exotic
Should have done more research before posting . Anyways somebody else might find this useful.
Gravity is zero at the center of the earth. how come the same set of equations predict the gravity to be infinity at the center of a black hole? where does the singularity really come into picture? how is a black holes center different from Earth's center?