What are parallel universes like?

Here, knock yourself out.
(Which, by the way, may be a very real possibility if you take these people seriously.
We do.
Which should explain a LOT. :))

But aren't multiple universes simply a theory, a fancy?
A theory, yes, but not really a simple fancy.

Here's what Aurelien Barrau, a particle physicist at CERN, has to say about it:
"The multiverse is no longer a model, it is a consequence of our models".

And it is to a parallel universe that Michio Kaku speculates humankind will migrate at the end of our earthly history.


Finally, here is a fabulously interesting (if not exactly brand new) documentary about it. Don't miss it.
(If you've watched it before, re-watch it. 
Even if you don't believe in watches. :))