No one knows for sure. There are theories, but absolutely none of them can be proved, and I doubt we will ever find out. The universe is expanding firther into what was here before the big bang....
i think thats not possable
Space, is empty space filled with millions of matter (or atoms) and dark matter. However, dark matter is very rare.
They use centrifical force machines to duplicate high G-forces. They train underwater to simulate weightlessness.
I believe it's called the swap space. Google it and look for your self to make sure.