Well, now I have been thinking some more about this story. This is my idea, not in any way to be suspected of having any reality to it.
The story suggests that our universe started out as a 1+1 dimensional universe, then switched to a 2+1 and then a 3+1 dimensional universe. My idea is that they don't really mean that the universe grew a whole brand new dimension on each switch. I suspect they they are working from a string theory perspective. When string theory was first developed it turned out that it would not work in a universe with 3 + 1 dimensions. They had to add more dimensions to make it work. However, since we don't see any more dimensions they decided the the extra dimensions were compact. That is, they are rolled up into very small bundles that were too small for us to detect them. An analogy from "Warped Passages" by Lisa Randall is the garden hose analogy. If you are sitting up in the nosebleed section at the stadium and you look at the far side of the field and see a hose that the groundskeepers left out it will look like just a one dimensional line. You have to get much closer to see that it has more than one dimension. So having said that I suspect that in the story on PhysOrg.com the original authors assumed that all the current dimensions of our universe were already there, but they were all compact dimensions, except the 1 spacial dimension that they think the universe started with. Then when the temperature of the universe dropped far enough the second dimension unrolled, and the universe became a 2+1 universe. Then as the temperature dropped further another dimension unrolled to give us our current universe. I have absolutely no idea why the dimensions would unroll as the temperature dropped. At first thought I would think that they would roll up as the temperature dropped. A drop in temperature would imply a reduced energy density, and therefore a reduced pressure. So I'm not sure how it works. But then I also have absolutely no idea how the math they use for all this works.
Bill Gill
