Well, I am not certain anyone or anything has gone to the other side of a black hole and made it back, the closest we've come to the other side of a black hole is in sci-fi fiction novels and more notably, in the movie 'Interstellar'. Nobody really knows what happens beyond the boundary of the black hole called the event horizon (It is where gravity is just strong enough to drag light back, and prevent it from escaping. Because nothing can travel faster than light, everything else will get dragged back also)

You can check out this post by Stephen Hawking alas, where he wrote extensively about black holes.