Enough politics. [1] Some NASA guys have found some peculiar, really large regions in the early universe that appear to be receding. The hook is that whatever is pulling on them appears to be farther away than the edge of the observable universe. [2] Dr. Alexander Kashlinsky has dubbed this phenomenon ‘dark flow’, heedless of political correctness in our current season of [3] electoral insanity.

I may be getting ahead of things, but it seems to me that [4] Alan Guth must find this good news. If confirmed, this discovery is another nail in the coffin of old-Big-Bang (i.e. non-inflationary) cosmology.  The only way something beyond the backward light-cone could exist is if the universe had some period of superluminal expansion.

I might as well use this post to address a recent query from CVM regarding the [5] musings of [6] Max Tegmark, a cosmologist at MIT. Dr. Tegmark is a proponent of the idea of [7] parallel universes. I read [8] his article in SciAm back in 2003. I have to say (1) I’m probably not competent to peer-review his technical papers, but (2) I was not impressed by the argument of an infinite universe filled with Hubble volumes, each with the same finite state space. The discovery of dark flow illustrates this problem — our Hubble volume is not closed. In technical terms, this means that there is no infrared limit to the energy a particle can have.  It has also never been obvious to me — perhaps I was asleep in 8.321 — that a finite-dimensional state space even necessarily implies a finite number of possible states. Without a finite state count, the parallel universe idea (at least in the simple “Level I” formulation that Tegmark posits) falls apart. These objections are simple enough that it seems that Tegmark would have confronted them.

Tegmark is actually a [9] prolific and accomplished cosmologist. It is an irony of our celebrity culture that his fame is due to musings of only marginal interest to actual scientists. It’s as though Stephen Hawking were known mainly for the wheelchair… oh, wait….