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Shape of the Universe Determined To Be Really, Really Flat
StartsWithABang writes: You might imagine all sorts of possibilities for how the Universe could have been shaped: positively curved like a higher-dimensional sphere, negatively curved like a higher-dimensional saddle, folded back on itself like a donut/torus, or spatially flat on the largest scales, like a giant Cartesian grid. Yet only one of these possibilities matches up with our observations, something we can probe simply by using our knowledge of how light travels in both flat and curved space, and measuring the CMB, the source of the most distant light in the Universe. The result? A Universe that's so incredibly flat, it's indistinguishable from perfection. Which means it's probably even flatter than Kansas.
Yeah - once you get into Rindler Horizons it gets a bit trickier - in that even if the universe is flat, unless we develop wormholes with some pretty extreme properties (even for wormholes) it is effectively finite from our perspective because there's no we can get to or receive information from a part of it beyond some distance (a bit further than the current observable universe.)