^As said by Orga.
And again, Nisorin, everything about Black Holes, including THEIR existence, is theoretical. The only reason we think they exist is because of patches of pure black in Space, where we think there should be stars behind. We dont have any solid evidence of their natural existence, and as such, they might not at all. Could just be that from a straight line to where these black holes are, there merely aren't any stars providing light that reaches us. We dont know yet.