I didn't quite follow the math there, but I think I understood enough.

I'll tell you, after watching the other 3 episodes in the 4 parter, my brain feels like it has melted (the one on the illusion of time was the one that almost hurt LOL).

It isn't as if most of what Greene talked about was new to me, but he put so much in a clearer way than any other science show I'd seen, better even than some of these ideas have been put across in science fiction. But the whole thing on the Casimir effect really puzzled me.

For a lay person who has never taken mathematics above Pre-Calculus, and my highest physics course I've taken was a high school physics class, I do think I tend to understand cosmology, string theory and theoretical physics pretty well (at least as well as can be done without the mathematical understanding). But sometimes some ideas just go past me, and this was one of them.

Another one I have a hard time wrapping my head around deals with the whole accelerating expansion of the universe (space itself getting larger). I have several questions about this:

1) If all the galaxies are moving away from each other, will the Milky Way and the Andromeda galaxies still collide in the distant future?

2) Is the expansion of space effecting the space between star systems within each galaxy? If not, why? Is the Dark Energy effect only occurring to the space between galaxies? Will it at some point effect the space between stars, planets, asteroids, or even the space between my atoms and molecules?

3) Couldn't the acceleration of the expansion of the universe be explained in another way? My idea has to do with the fact that they say spacetime is curved. This leads me to imagine our 3 dimensional world (not counting T here) as the surface on a 4 dimensional sphere/globe. Let's call the north pole of this globe the point of the Big Bang. As the universe expanded, it expanded southwards on our imaginary globe. The way I visualize this, it seems that after passing the "equator" everything would seem to be moving away even faster. The thing is, I also see it as not just expanding, but actually moving towards itself, to a big crunch as it arrives at the "south pole" of the globe. I realize I am probably very off on this, but would someone explain to me why (I figure the why is pretty simple actually, but I'm missing it).