A Black hole is caused by the collapse of a neutron star's core (i.e. the leftovers that sometimes occur after a star dies.) It spreads over a funnel-shaped (more or less) area in space, with a central point of theoretically infinite mass called a singularity, which exerts amazing gravitational force. Even light can't escape.

According to science, recreating a singularity (or as close to it as you can) is pretty much recreating the condition of the universe before the Big Bang. According to the same line of thinking, the world may end in the reverse of the Big Bang, or the theoretical 'Big Crunch.'