Jeez, tough crowd

I haven't read all the replies, but the theory I am aware of about the contracting-expanding-contracting universe is where right now we are inside a giant black hole where the even horizon contains the whole universe, so no, you could never escape

This is possible because the larger the sphere, the less dense it is required to be for it to be a black hole. For instance, you could have a density of 1 atom per cubic light-year, but as long as this is true for a big enough sphericall volume, you have a black hole. I think.