Some comments: The supposed infinitely dense point (a singularity) can't have been "in space" because there was no space. Since time didn't exist either (except inside the singularity) there can't have been any "start" as such. In fact, any description of the assumed singularity cannot include anything related in any way to space or time. The description should be independent of space and time--a problem, since physical descriptions depend on both. Moreover (ain't that a cool word?) the infinitely dense "point" is only a logical conclusion based on "running the expansion backwards"; it's possible that the universe was instead "smeared out" and smooth rather than pointlike, before time or space emerged by whatever mechanism.