Could Earth be inside a black hole?

And for that matter, could our universe be inside a black hole?

2 comments

tl:dr: possibly, but if so, it would be the size of the entire universe and, as a result, impossible for us to determine one way to the other.
I didn't find any ArXiv links in the page, but the main point is this: given how flat the Universe is, if it is inside a black hole, it needs to be really large in order to keep the curvature inside so flat.