[sithu]

I'm by no means a physicist but find topics on the nature of universe deeply fascinating. One thing i've always found frustratingly difficult to grasp though, is the expansion of the universe - but just found this article to be a total eye opener: http://en.wikipedia.org/wiki/Metric_expansion_of_space

It was counterintuitive to me how we can observe light from objects 12 billion years old, when supposedly things are flying apart faster than the speed of light. Is there an edge of the universe, and what is outside that we are 'expanding into'. If everything is moving apart, why are we going to crash into Andromeda? Why haven't black holes consumed all the mass in the universe by now? If the cosmological principle is true and the universe looks the same in all directions, doesn't that imply that we're either at the center- or that it wraps around and we just can't observe it? Saying it's infinitely large seems like a convenient explanation.

The idea of metric expansion of space between gravitationally unbound matter, local groups, and Hubble flow explain a lot.

I do still wonder though how accurate our understanding of the universe really is, or if there's some fundamental thing we've missed and have generated theories to fit the observations we're currently capable of making.