The top posts of 2007: number 1

Over the holiday period, the physics arxiv blog is re-running the most popular blogs (by page views) of 2007.  This was the one ya like the most [cue drum roll]:

Why our time dimension is about to become space-like
9 October

It don’t get much weirder than this. The universe is about to lose its dimension of time says a group of theoretical astrobods at the University of Salamanca in Spain. And they got the evidence to prove it.

The idea comes from the study of braneworlds: the thinking that the universe we see around us is a 4-dimensional cosmos called a braneworld embedded in a multidimensional universe. The “signature” of our universe is the number of space and time-like dimensions it has: in our case we got 3 space-like dimensions and one time-like dimension. It’s what astrobods call a Lorentzian universe. So far so good: lots of astronutters think the same thing.

But our universe may not always have been like this. Some theorists think it may once have had a Euclidean signature meaning that all the dimensions were space-like. Now Marc “Bars” Mars and a few pals in Spain say that the Universe’s signature might be about to flip from Lorentzian to Euclidean. In other words, our dimension of time is about turn space-like. Gulp!

This ain’t entirely bonkers and here’s why. Bars Mars has calculated what it’s like to be an observer in a universe that is about to flip and get this: it would look as if it were expanding and accelerating away from us. Sound familiar?

Yep, it’s exactly what astrobods have been observin over the last few years, a phenomenon they attribute to dark energy. If Bars Mars is right, dark energy ain’t got nothing to do with it and we’re all starin’ down the barrel of a cosmic catastrophe.

Still, maybe four space-like dimensions will be better than three. Who needs time anyway?

Ref: arxiv.org/abs/0710.0820: Is the Accelerated Expansion Evidence of a Forthcoming change of Signature?

One Response to “The top posts of 2007: number 1”

  1. R. Mirman says:

    It certainly doesn’t get any weirder, or nuttier. It has long been known that a universe would be impossible in any dimension but 3+1 (boring; it agrees with reality). For proof see
    the book
    Our Almost Impossible Universe:
    Why the laws of nature make the existence of humans extraordinarily unlikely
    R. Mirman