System of units and coordinates

There is nice post by John Baez on system of units and coordinates:

"... systems of units are like coordinates. They’re both systems of arbitrary choices that let us describe reality using numbers. In both cases, we’re ultimately interested in learning things that don’t depend on these arbitrary choices."

The discussion is quite good and interesting.

Brazilian Meeting in Particles and Fields

This year the Brazilian Meeting in Particles and Fields was held in Águas de Lindóia, a small town near São Paulo. Every year we have a meeting of experimental and theoretical physicists working in high energy physics and field theory in Brazil. The audience is very broad. There are plenary talks which are supposed to be non technical and also more technical parallel talks, besides short oral presentations and panels. Approximately 300 physicists and students were present. The program can be found here. Wireless was available but the connection was poor. On Monday we spent almost all day without internet but in the following days the situation got better.

The meeting started on Sunday night when David Gross was awarded with the title of Doctor Honoris Causa given by the São Paulo State University. He gave a talk, The Future of Physics, where he discussed his favorite 25 problems. It seemed to be an updated version of the talk he delivered during the celebration of the 25 years of the KITP two years ago.

On Monday there were two good talks, one about cosmic inflation by Viatcheslav Mukhanov and another on astroparticle physics given by Angela Olinto. Angela is a Brazilian physicist and the chair of the Department of Astronomy and Astrophysics at Chicago University. She also works in the Auger Observatory, the biggest cosmic ray laboratory now in operation. Then Nathan Berkovits gave a parallel talk on string amplitudes. It is always difficult to talk on technical stuff to a large audience.

In the evening we had a round table on the anthropic principle. Originally Susskind had been invited and it seemed natural to have such a round table. But then he cancelled his participation and the round table was kept in the program. It was something surreal. Nobody in the table was in favor of the anthropic principle. Hitoshi Murayama presented some points pro the anthropic principle and then everybody, including Murayama , talked against it.

On Tuesday we had a very good talk on the physics beyond the standard model given by Murayama. He presented many usual topics like the hierarchy problem from a new perspective. In the afternoon Burt Ovrut talked on the heterotic string, the standard model and cosmology. Again, too technical and it was very hard to follow him.

On Wednesday we had an experimental plenary talk given by Guenakh Mitselmakher on the LHC. It seems they will start to collect data only in the spring of 2008. In the afternoon David Gross gave a talk on string theory, The Coming Revolutions in Fundamental Physics. I think it is the first time the experimentalists in Brazil have been subject to such an exposition of string theory. It must have been frightening to them but I have to talk to some of them to find out.

There were many short oral and panel presentations. My feeling is that there was more work done in string theory than last year. This is good news.

The talks are already available in the homepage.

O universo elegante na Google video

No Google video voce pode encontrar uma versão reduzida da série de tres filmes O Universo Elegante, de B. Greene. No site da PBS a série está disponível em vários capítulos. No Google video a série foi compactada em tres episódios:

Einstein's Dream

Strings the Thing

Welcome to the 11th Dimension

Banda larga é realmente necessária. (Via blog do L. Motl)

Last solar eclipse in 2006

It starts tomorrow, Friday 22, at 9:48 GMT (6:48 in Brazil). It is an annular eclipse which will be seen in South America, Caribbe, western Africa and Antarctica. Maps and more details can be found at NASA. Wake up early!!!

Lorentz invariance in good health

A new test of Lorentz invariance was announced in gr-qc/0609072. Two cylindrical sapphire microwave resonators, which are perpendicular to each other, are set in rotation. Standing waves are set up in the resonators and if the velocity of light is not isotropic there will be a change in the frequency difference as the resonators rotate. This experiment was performed before but now more than one year of data was accumulated improving earlier results by a factor of 10. Lorentz invariance is still up.