I've read and been told that, based on the distance between repeated irregularities in the microwave background radiation, we can now conclude that the universe is flat rather than open or closed. I heard this again at the excellent presentation given by Dr. Lawrence Krauss last night at the World Science Festival event. I understand this to mean that the curvature (average curvature?) of the universe is 0 rather than positive or negative. Is that the right interpretation? If so, I don't understand how this can be be determined by such a measurement. Every measurement has some possibility of error. I can see how one could definitively conclude that the curvature of the universe is positive or negative, but not that it is exactly 0. If anyone can help me out here, I'd appreciate it.

I'm just a member of the general public with no religious or personal axes to grind. Except one, whenever I attend a public lecture about astronomy and related fields, there are references to absolutes such as the microwave background being the edge of the Universe, that reek of conjecture. Is this just the culture of Science projecting a united visage of intellectual certainty? I enjoy the public programs at the Rose Center, but it always knocks me out when the driver pulls back the projection of our position in our solar system, then in our galaxy, ad infinitum, that is until we get to what we project as the edges of the universe. Though Science be great, though the imagination of Man is great, when we see the gargantuan distances of space with it's multitude of possibility, a posture of certainty always reeks to me of a clear sign of our intellectual limits. Biological limits?