> which I think is wrong for the standard cosmology. I have no idea why you would think that, since the very paper you link to explicitly shows diagrams in whi

> which I think is wrong for the standard cosmology. I have no idea why you would think that, since the very paper you link to explicitly shows diagrams in which the Big Bang is obviously not a single point but a spacelike line. > Why would (cosmological) t=0 be a line rather than a point, a 3-volume, or some even weirder non-Lorentzian structure? Because that's what you get when you take the appropriate limit. > Obviously I've seen Penrose diagrams with the BB drawn out to look like a horizontal line, but have never taken that to be anything other than for legibility or print-reproducibility reasons, similar to the dimensional reduction of the diagram itself. You are mistaken. The point of a Penrose diagram is to show causal structure; that is how it is constructed, so that light cones on the diagram exactly match light cones in the spacetime it's a diagram of. That means that if it were really true that the entire universe was in the future light cone of the Big Bang, the Big Bang would have to be a point, and the diagram as a whole would be an inverted triangle that was the future light cone of that point. Which obviously is not the case for Penrose diagrams of the universe as a whole. As for "published authority", as I noted above, you gave one yourself: the Davis & Lineweaver paper. It agrees with what I have been saying, not with what you have been saying. > I agree that in the standard cosmology there are an infinite number of causally disconnected points one "instant" after the Big Bang Then you are contradicting yourself, since this is impossible if the Big Bang is a point. It is only possible if the Big Bang is a spacelike line. > but don't see how that can't follow from the standard BB singularity. It does. The issue is not "the standard BB singularity", but your mistaken belief that that singularity is a point. It's not. It's a spacelike line.