Occam's Machete: Cosmology

One of the biggest stories in Cosmology over the last two decades has to be the discovery of the accelerating expansion of the universe. It left most scientists gob-smacked but has received no serious criticism since the evidence, mostly taken from type 1-A supernovas, continues to pile up. If the red shift of the 1-A flashes were the only evidence there might be other explanations for the data. Shouldn’t there be some other independent way to verify the expansion data, something that helps validate the explanation?

I love watching for these weird effects and anomalies because, once in a great while they pan out to be the real deal and lead to new science. Enter an international team of researchers led by Masamune Oguri at Kavli IPMU and Naohisa Inada at Nara National College of Technology who have conducted a unique survey of gravitational lensing effects. They calculate the probability of lensing at various times in the past to produce a model. But when the model is fit to the survey data it produces an acceleration very much consistent with the type 1-A red shift measurements. Woohoo, one more vote for Einstein’s Cosmological Constant.

If Roger Zelazny had written the Amber books today I’m sure he would have had a Courts of Entropy instead of Chaos.  But I digress…

The Holographic Principal states that a 5-D universe can be encoded holographically on a 4-D universe.  Just as a 3-D object can be captured in a flat hologram.   The implications are that the supertring universe of 5 dimensions can be seen by thinking of our own universe as a hologram.  Using this principal some really smart guys (including George Smoot of Nobel fame) proposed on arXiv that dark energy in our universe is only a holographic affect of an entropic force in higher dimensions.

They develop their theory and use it to predict the amount of dark energy we should see in our universe.  Unless there are mistakes in their reasoning, which I cannot judge, the most interesting thing is how close the prediction is to the dark energy seen in the supernova data—you know the data that showed our universe is expanding at an accelerating rate.  The other interesting thing is this how people are beginning to find observable predictions in String/M-theory.

I’m going to have to pay more attention to this Entropy stuff.

BTW Motl has some thoughts on this paper too.