Black holes originate from collapsing stars that become so dense and heavy in such a small area that they stretch the very fabric of the universe sort of like a sheet of rubber and a very heavy ball bearing. The ball bearing's weight pushes down through the sheet of rubber and forms a cylindrical tunnel through the space and time continuum and create's an intense gravitational pull. So strong even that light traveling at 186,00 miles per hour cannot escape. No one knows if the tunnel has an exit at the other end. If you were to send in a photographic probe or a spaceship or anything else for that matter, it would be stretched as thin as a strand of spaghetti. Black holes are also invisible. They can only be spotted to date, by objects swirling around the outer rim of the hole before their sucked in.