space isn't just big, it's weird too

Today I found myself reading about Zarmina and how people might one day fling themselves toward it at a large fraction of c by sticking a firecracker worth about 1.8 x 10^25 Joules of energy on the end of the ISS and lighting it up.  Cool beans.

This lead me to an interesting clickfest at Wikipedia where I hopped from current and upcoming exoplanet surveys, to finding distances and pinpointing objects with various coordinate systems where I had a flash back to the movie Contact (yes I read the book, of course it was better). I then wound my way round to the bigger items of interest like the age of the universe and the size of the observable universe where I found something crazy. It was so crazy my mind stumbed, fell, got up and dusted itself off then immediately fell again and stayed there in the dirt for a moment trying to decide what to do next.

Now to preface this I should say that I read some time ago that it is thought by some that when travelling the universe, as when travelling the surface of the Earth, you could pick a direction and travel in it and eventually if you kept at it long enough you'd find yourself back where you started.  Conceptually it makes sense to us on a planetary scale but I suppose you need a certain amount of years seated before a blackboard discussing planes and vectors and toroids and so on before it starts making sense with the whole universe.  I took it at face value that it was one theory that smart folks had given some thought to and went about my business. 

Then today I read this:

"It is also possible that the (physical) Universe is smaller than the observable universe. In this case, what we take to be very distant galaxies may actually be duplicate images of nearby galaxies, formed by light that has circumnavigated the Universe. It is difficult to test this hypothesis experimentally because different images of a galaxy would show different eras in its history, and consequently might appear quite different."
Roll that thought around your noodle for a while.  Weird right?

Anyway the article goes on to say that this idea was disputed this summer by some very clever sounding folks in their article "Observable circles-in-the-sky in flat universes".  If it makes any sense to you by all means please direct me to a pre-chewed version, I haven't the chops for such stuff.