Wednesday, 5 October 2011

Nobel Prize of Physics for Accelerating Universe

I think it's a little late for this now, but as I had this draft on my blogger, I thought I'd better publish it or delete it. I decided to publish it.

The Nobel Prize of Physics of this year was given to the discovery of the accelerated rate of expansion of the universe by means of supernova measurements. It was awarded jointly to Saul Perlmutter, Brian Schmidt and Adam Riess, the last two members of the High-z Supernova Search Team.

I'm gonna write about the accelerated expansion in the following, but one of the reasons I decided to publish this post instead of deleting it was that this is the second year in a row that I predicted correctly the prize. Unfortunately, the prediction of the Nobel for the discoverers of the graphene last year didn't really count for anyone but me because I never really wrote it anywhere, so I don't have any proof. However, I have the proof for this year's prize in this post I wrote last year:

Just take a look at the last paragraph.

Now that I did some marketing, which seems to be the most important thing in science today (sic), I'll get back to explain the meaning of the discovery. It is actually a big lesson for those who still think that science is made by consensus (just to stress it, they are wrong). Before this measurement, there was not much certainty about the rate of expansion of the universe, except that we already guessed it was expanding based on the Doppler shift of the galaxies measured by Hubble. However, there was a "consensus" (sic, again) that the universe should be decelerating. Many important physicists supported this idea. Stephen Hawking, which is undoubtedly a good physicist, was one of them. The main reason was that this hypothesis was more elegant theoretically.

Don't get me wrong, it is completely okay to support a preferred hypothesis for its elegance if there is no piece of evidence whatsoever supporting any of its rivals, as long as you leave it clear that it's just a personal preference. It works fine as long as you are aware that it is just a choice, or a working hypothesis, that still MUST be confirmed by experiments at some point.

For those who believed religiously on the deceleration, the 1998 supernova result was a shock. It is also a fine argument to throw against that friend of yours who thinks that science is a social construct and reality is exactly what people believe it to be (although you never really win against those people). Once the results were checked and confirmed, the good scientists obviously had no problem in accepting them (just don't forget that nothing in science is beyond doubt...)

The implications of this discovery are quite interesting. By one side, it means that the universe will not end up in a Big Crunch, where everything will disappear in an ultimate singularity. However, it means that in the very long run, everything will suffer from a kind of death by isolation as the space between things will continually stretch, although I guess it is not clear if the expansion will be strong enough to separate electrons from their atoms. 

The isolation comes from the fact that as the rate of expansion increases to a velocity higher than that of the light, the bodies which remain more or less together will simply not be able to communicate with the other lumps of matter as nothing could travel faster than light (forget momentarily about the OPERA neutrinos, even because I'm far from being convinced about that result). This isolation is not depressing, but also can be the source of several philosophical problems related to what is real or not, as one lump is in practice severed for ever from the other and there are no measurements one can do about the other. 

Nobody really knows what's causing the acceleration and many ideas have appeared to try to explain it, including the usual scalar field, which is usually conjured to fix almost everything in the universe. In this case, it was called quintessence, but it's still to be made work. In general, the convention is to call whatever is causing the expansion dark energy, just to have a more general working term. That is a hot topic of research and apparently far from being solved.

I will finish by giving a new Nobel Prize prediction. I think next year's goes to Quantum Computation/Information, probably to Ben Schumacher and Peter Shor. There are other possibilities, like the iron pnictides superconductors or spin glasses (probably for Parisi at least), but I will stick to the QC people this time.