Physics

I guess every profession has its own kind of personalized spam. Here is a couple of recent samples from my own: From a Fermilab address: "According to the TRAIN database training for course FN000508 / CR - Workplace Violence and Active Shooter/Active Threat Awareness Training expired on 07/01/2014. Please make arrangements to take this class. If this training is no longer required then you or your supervisor should complete the Individual Training Needs Assessment [...]" Note that (1) I am not a user any longer, so their database is at fault. They still send out these notifications anyway…

Recently this headline on Real Clear Science caught my eye: Carbon-12 Nucleus Shaped Like Equilateral Triangle.  It led to an article in Physics World, entitled Carbon nucleus seen spinning in triangular state This is one of the many sorts of things that fascinate me, and so I started chasing press releases and original papers.  Now Wikipedia tells us that Stories or narratives have been shared in every culture as a means of entertainment, education, cultural preservation, and instilling moral values. I feel that the storytelling element is so often left out of science, and…

In the 1980s, the discovery of soccer-ball-shaped carbon molecules called buckyballs helped to spur an explosion in nanotechnology research. Now, there appears to be a new ball on the pitch - a cluster of 40 boron atoms forms a hollow molecular cage similar to a carbon buckyball. It's the first experimental evidence that a boron cage structure, previously only a matter of speculation, does indeed exist. Carbon buckyballs are made of 60 carbon atoms arranged in pentagons and hexagons to form a sphere—like a soccer ball. Their discovery in 1985 was soon followed by discoveries of other…

In the process of revising a chapter of my book, I found a clip I would like to share here, as it contains an analogy I cooked up and which I find nice enough to be proud of. Well, two analogies, as you'll soon find out; here I am speaking of the cat weighing trouble at the end of the piece - the other is quite trivial. The topic is the widely different masses of fermions, the building blocks of our universe, and the trouble in making sense of it and of measuring precisely their values. Comments welcome! Mass is a mysterious intrinsic property of matter corpuscles. We are accustomed to…

The 37th International Conference on High Energy Physics (ICHEP) began last Thursday in Valencia, Spain with three days of parallel sessions, now moves on to plenary sessions until Wednesday, summing up the current state of the art in the field. The plenary sessions will be webcast. The LHC experiments ATLAS, CMS, ALICE and LHCb presented new results from the LHC’s first run, which concluded in 2013. For ATLAS and CMS, the run-1 Brout-Englert-Higgs (BEH) analyses are reaching a conclusion and all show that the Higgs particle behaves in a way consistent with the Standard Model: the theory that…

Two years have passed since the discovery of the Higgs boson (on July 4th, 2012), and the young particle still causes excitement. Originally it was the excess of Higgs decays to photon pairs as seen by the ATLAS experiment - but that anomaly has vanished with more data and more careful analyses. Then, it was the turn of the twin peaks: ATLAS again saw an inconsistent mass measurement with photon pairs and Z boson pairs. Both those "anomalies" were at the level of 2-sigma or so -which means the data had a probability in the 1-5% range of being observed like that if the Standard Model was…

Among the many more-or-less boring news from the ICHEP conference (International Conference on High Energy Physics), which is presently going on in Valencia (Spain), one bit today is sending good vibrations through the spine of many of the few phenomenologists who have chosen to remain faithful to the idea of Supersymmetry all the way to the bitter end. It is the excess of diboson events that ATLAS has just reported there. W bosons are the massive particles discovered in 1983 by Carlo Rubbia at the CERN SppS collider. They govern weak interactions, the ones responsible for radioactive decays…

A couple of weeks ago I reported here about the new measurement of the Higgs boson mass produced by the ATLAS experiment. That determination, which used the full dataset of Run 1 proton-proton collisions produced by the LHC in 2011-2012, became and remained for two weeks the most precise one of the Higgs mass. Alas, as I wrote the piece I already knew that CMS was going to beat that result very soon, but of course I could not say anything about it... It ached a bit! That's why I am quite happy today to report that CMS has again taken the lead in this LHC-internal competition. One which is…

In cosmology, cold dark matter is believed to be a form of matter which moves slowly in comparison with light and interacts weakly with electromagnetic radiation. It is estimated that only a minute fraction of the matter in the Universe is baryonic matter, which forms stars, planets and living organisms. The rest, comprising over 80%, is dark matter and energy. Dark matter is considered a theory because it has to exist - it just isn't defined. The current theory is instead an intellectual method to explain how the universe evolved from its initial state to the current distribution of galaxies…

In quantum physics, you can't precisely measure momentum and position simultaneously. They are an example of conjugate variables, connected by Heisenberg's Uncertainty Principle. There are workarounds, such as "weak measurement," to measure both at the same time but a new study says that a technique called compressive sensing also offers a way to measure both variables at the same time, without violating the Uncertainty Principle. When measuring quantum systems each detection event gives a little information about momentum and a little about position, so that information about the whole…