Georges Charpak, a French physicist and 1992 Nobel Prize winner, died yesterday.
Of Polish origin, Charpak gave crucial contributions to experimental physics, in particular for his invention of the multiwire proportional chamber in 1968.
Back then, the signal of passage of charged particles was recorded by bubble chamber images and images triggered by spark chambers - where the charge deposition would create a discharge in a very high electric field.
Duality is one of the most important insights in physics and philosophy of physics. What does duality mean? It means that there are dual descriptions of one and the same observed physics. Duality implies that you cannot possibly decide whether the one description T or the other, to T dual description T’ is right or wrong, because both descriptions lead to the exact same observations for the observers who live in a universe that can be described by the theories T and T’. Both are equally right or wrong, as they are dual descriptions.
With the fresh news of the election of Pierluigi Campana as spokesperson of the LHCb experiment, the Italian participation to the LHC experiments at the CERN laboratories is close to a grand slam: three of the four experiments along the ring are led by Italian physicists. Campana joins Guido Tonelli (CMS), Fabiola Gianotti (ATLAS), and Jurgen Schukraft (ALICE).
Italians have consistently led CERN experiments, so the election of Campana is no surprise to most of us: still, it speaks volumes about the professionality of Italians in high-energy physics and the recognition that they are given by their colleagues abroad.
A week from now, Tuesday October 5th, the winner(s) of the 2010 Nobel Prize for physics will be announced. Predicting the Nobel laureates in physics is notoriously difficult
. As part of their overall Nobel prize predictions, each year Thomson Reuters attempts to predict
the winners in physics, but despite their habit of listing multiple candidates, so far they never managed to hit any of the annual winner(s).
This year Thomson Reuters might, for the first time, be lucky
Pickering is quite a name in the philosophy of science, or science studies, sociology of scientific knowledge (SSK
), or science and technology studies (STS).
He is especially interested in physics and writes
about so called “old” versus “new” science. He means and to this day insists on the difference being soft versus hard scattering in particle collider experiments, the latter being something that happened around the time he started to look into physics more than 30 years ago (oh coincidence).
The Large Hadron Collider is increasing gradually the number of proton bunches that circulate in the machine. Yesterday's fill saw 104 colliding proton bunches, producing the record instantaneous luminosity of 3.5 x 10^31 collisions per square centimeter per second. This is no surprise, of course: luminosity is essentially the product of the number of particles crossing each other per second divided by the cross section of the beams, so if you increase the particles and manage to keep the beam transverse size constant, luminosity must go up.
"At that time, although recognized for the very high quality and reliability of its accelerator engineering, CERN unfortunately did not have a similar reputation in its physics, and it was still recovering from disasters such as the "split A2" affair. CERN always seemed to be second best behind the leading U.S. laboratories, with their vastly more experienced physicists. And during the 1960s it had been repeatedly beaten into the ground, for example, over the discoveries of the Omega- hypheron, the two types of neutrinos, and CP violation in K0 decay. All these things could and should have been found first at CERN, with its far greater technical resources, but the Americans had vastly more experience and know-how."
Scientists know that time passes faster at higher elevations. It's a curious aspect of Einstein's theories of relativity that previously had to be measured by comparing clocks on the Earth's surface and rockets.
But NIST physicists have made it a lot more personal - a scale of about 1 foot - and showed that you even age faster if you are taller than your relative. The good news is you won't be able to see the difference, that one foot difference in height adds about 90 billionths of a second over a 79-year lifetime.
The NIST researchers also observed another aspect of relativity, that time passes more slowly when you move faster, at speeds comparable to a car traveling about 20 miles per hour.
Despite time is a scarce resource for me these days, and my "working time balance" shows deep red, I am presently spending some of it to investigate a very interesting statistical effect of general nature, although specially connected to the issue of discovery thresholds in particle physics.
I am triggered by the recent eported observation of a new particle, which has been claimed at a significance corresponding to the coveted 5 standard deviations after a previous evidence had been extracted from 40% less data at 3.8 standard deviations. The matter has left me slightly dubious about the precision of the latter claim.
Now, before I state the problem, let me explain in short how significance is calculated in these kinds of new particle searches.
I devote only a short piece today to the topic of the week -or the month- in particle physics: as many of you already know, yesterday the CMS collaboration has made public
the results of their analysis of two-particle correlations, which evidences an effect never seen before in hadronic collisions, and which has been saluted very emphatically by the press around the world.The Analysis In Ten Lines