It's been speculated that the entire visible universe could be inside the event horizon, the point of no return of an enormous black hole, and there would be no way to tell... Until we got close enough to the singularity I guess.
Yes, this is actually fascinating and one of the most incredible theories, IMHO. I would not be surprised if the entire Universe we live in is a black hole, where the physics of the black hole cause a time illusion in the form of matter/entropy taken from a parallel Universe. This is not science fiction, it has been proposed as a real theory. nitro
Did you hear Jesse Jackson apologized to the American Academy of Scientists for having called them racist?