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!
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
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.
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.
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!
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.
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.
Do you remember the top quark asymmetry measurements of CDF and DZERO ? A few years ago they caused quite some excitement, as both experiments were observing a departure from standard model expectations. This could really be the place where one would first observe new physics associated with top quark production, so the analyses triggered quite some theoretical investigations, deeper studies, and model building.
By trapping a magnetic field with a strength of 17.6 Tesla, roughly 100 times stronger than the field generated by a typical fridge magnet, in a high temperature gadolinium barium copper oxide (GdBaCuO) superconductor, researchers not only beat the previous record by 0.4 Tesla, they harnessed the equivalent of three tons of force inside a golf ball-sized sample of material that is normally as brittle as fine china.
You wouldn't think that mechanical force, like kicking a ball in the World Cup or embossing letters on a credit card, could process nanoparticles more subtly than the most advanced chemistry but a current paper in Nature Communications describes a now patented method to use simple pressure — a kind of high-tech embossing — to produce finer and cleaner results in forming silver nanostructures than do chemical methods.
All without harmful byproducts to dispose of.