concept of black hole

we know from gavitaional law that force of gravity is given by,

g=GM/R^2
so if we go on decrease the radius keeping the mass constant then force of gravity goes on increasing.If we take radius of an object of mass M to be zero then force of gravity becomes infinite.Its gavitational force becomes so high that even light cannot exist there so it appears black. So a black hole can be considered as a region of empty space with a point like singularity at the center and an event horizon at the outer edge . Research on this subject indicates that, rather than holding captured matter forever, black holes may slowly leak a form of thermal radiation.