Saturday, February 20, 2010

Rocket launch and some vintage papers

Back in my local, back to the Chinese, the weekly routine continues as inevitably as the Galician rain outside. This week has flown by faster than ever, with a few breakthroughs in work coming in short spaces of time, with periods of treading water in between. Still, the treading of water allows subconscious processes to explore parameter space, or so I I like to kid myself.

In the last few weeks we've set up a student and postdoc vintage journal club, looking over the most important papers in the field from the last few decades. Yesterday was my turn to discuss Gross and Neveu's 1972 paper on dynamical symmetry breaking in asymptotically free field theories - a fascinating and important paper coming directly after the discovery of asymptotic freedom in non-abelian gauge theories. It's been many years since I calculated a Feynman diagram in anger and this gave me a good chance to remember the wonders/horrors of renormalization, away from the AdS/CFT context. It was also a good chance to talk on a subject that I don't work on, and although I hadn't formally prepared anything to say, it took around an hour and a half at the board to get through the bulk of their work.

I'm finding the process of going through these truly foundational papers extremely useful. The Gross and Neveu paper alone deals with so many things which have to be on the tips of our tongue in day to day research: large N expansions, goldstone's theorem (especially its caveats in two dimensional theories), the emergence of tachyons and the study of false vacua, the study of perturbatively exact generating functionals and much more. We have a list of around 20 or so papers to go through over the next few months and I can see this being extremely profitable as a time investment.

Anyway, I really wanted to write a post as an excuse to show the following video, seen on Badastronomyblog yesterday. This is an incredible phenomenon I've never seen before.

There are a few different explanations on BABlog, but this was my interpretation:
As the rocket passes the cloud layer, a region of sky where the pressure, temperature and humidity are just right for the condensation of water vapour, the shock wave from the rocket creates a ripple of low and high pressure through the layer of air. Those areas which were just on the point of condensing water suddenly condense as the ripples pass and the result is this inverted rock in a pond effect. The fact that there is a sundog there meaning that there is ice in the layer of cirrus makes for some other explanations but the above is my take on it. Any additional thoughts are welcomed.

1 comment:

Nitin said...

Could you please copy-paste that list of papers for our benefit Jonathan? I am curious about the papers you have on your list. We had a similar HEP-seminal-papers-review thing organised by Robert Helling in Munich about 2 years ago, but unfortunately, that was the only time it happened.