The graviton! Muah haha! Seriously...if it existed. Or at least if we could prove its existence. That seems to be the whole point to building the Large Hadron Collider.http://www.star-signs.org/compatible-star-signs.htm .to figure out and prove what keeps everything in place in the universe. :)...
I definitely think that this is a possibility (that the other side of a black hole is an expanding universe). You'll see a lot of people in physics-related occupations that will tell you "no" or "that's not possible" because they think so analytically about singularity and all of this stuff...