Symmetry factor

Yesterday the infamous Ig Nobel awards were handed out. Here are some of them:

ACOUSTICS — D. Lynn Halpern, Randolph Blake and James Hillenbrand, for their experiments on why people dislike the sound of fingernails on a chalkboard.

MATHEMATICS — Nic Svenson and Piers Barnes, for calculating the number of photographs you must take to ensure nobody in a group photo has their eyes closed.

PHYSICS — Basile Audoly and Sebastien Neukirch, for their insights into why dry spaghetti often breaks into more than two pieces when bent.

CHEMISTRY — Antonio Mulet, Jose Javier Benedito, Jose Bon and
Carmen Rossello, for their study “Ultrasonic Velocity in Cheddar Cheese as Affected by Temperature.”

What can I say? At least they are practical… I remember that a couple of years ago there was a geography prize awarded for disproving the common expression that “Kansas is as flat as a pancake” (it turns out that Kansas is actually flatter). Maybe the awardees are now trying to find restrictions on the use of the phrase “smooth as baby’s behind.” Although it would probably be an Ig Nobel prize in medicine…

P.S. Oh, yes, the biology one:

BIOLOGY — Bart Knols and Ruurd de Jong, for showing that female malaria mosquitoes are attracted equally to the smell of Limburger cheese and to the smell of human feet.

I kinda suspected that that was true…

So, the 2006 Nobel prize in physics was awarded to John C. Mather and George F. Smoot (leaders of the COsmic Background Explorer (COBE) satellite experiment) “for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation.” Once again Thompson Scientific got it completely wrong (not even close!), proving that Nobel Prizes are not awarded by a simple majority of votes…  

So, what is cosmic microwave background radiation (CMBR) and why it is anisotropic? There are nice reviews about that, including this one from the Particle Data Group, written by one of the awadrees. Anyways, the short story is that microwave background radiation, whose existence was proposed by George Gamow in 1946, comes as a consequence of the Big Bang. Hot plasma of various particles (including photons) produced in a Big Bang expanded and cooled down to a point when charged electrons and protons started to recombine into the neutral atoms, leaving photons decoupled. So this cooled-down photon bath now has a temperature of about 2.75 K (radiowave frequencies) and a spectrum of a black-body radiation. It turns out that this CMBR can be anisotropic due to various effects. For example, photons of CMBR would change energy (and thus temperature) in a gradient of some gravitational field (loose energy, or be redshifted, in an increasing potential and vice versa — the so-called Sachs-Wolfe effect). Or due to density fluctuations… Those anisotropies are tiny, of the order of thousandth of a percent! The observation of this effect, however, is a major discovery, as it connects us to the physics of the early universe.

So in 1989 a specialazed satellite experiment (above-mentioned COBE)  was launched to study those anisotropies. The results were reported in April of 1992. The project leaders got the Nobel Prize!    

There is, as always, a controversy. The thing is that in July 1983 an experiment Relikt (another link is here) was launched aboard the Prognoz-9 satellite to study cosmic microwave background radiation. The experiment carried out studies of the CMBR using only one frequency. However, in January of 1992, Andrei A. Brukhanov presented a seminar at Sternberg Astronomical Institute in Moscow, where he reported about the discovery of anistropy of CMBR. The results were published in journals Soviet Astronomy Letters  and later in Monthly Notices of Royal Astronomical Society (see references above following the Relikt link).

Interesting story, don’t you think?

2006 Nobel Prize in physics will be awarded on Oct. 3 — just in a couple of days. Of course, there is already an active discussion in blogosphere about who should get it. In fact , Thompson Scientific (yes, publisher of our algebra-based General Physics textbook) has a poll with the following results:

49% - Desurvire, Nakazawa, Payne (condensed matter: fiber optics)
32% - Fert, Gruenberg (condensed matter: giant magnetoresistance)
20% - Guth, Linde, Steinhardt (cosmology: inflation)

Although I think that this year it’ll go to someone more “applied” (which would make contestant number 2 above the most likely candidate), I can suggest a couple of candidates in particle/nuclear physics:

• Makoto Kobayashi, Toshihide Maskawa, and maybe Nicola Cabibbo for mechanism of CP-violation in the Standard Model;

• Yoishiro Nambu and Jeffrey Goldstone for mechanism of spontaneous symmetry breaking;

• James Bjorken for scaling in QCD

Any other ideas?

This semester is drawing to close. Well, Spring Break hasn’t even begun yet (next week!!!), but all the signs are that summer is not far… Soon, it will be Student Evaluations time. I guess every University has them but every universtity use them in a different way. Here I want to talk about different kind of evaluations.

Students talk about teachers: http://www.ratemyprofessors.com
Teachers talk about students: http://rateyourstudents.blogspot.com/

Check them out, quite an interesting read…