Physics
Now that the first of the Moriond conferences is over, and just as the second one starts, it is time to have a detached view at the Higgs boson results presented there this far by the CMS and ATLAS collaborations, to summarize where we stand and what new information we have gained since last fall, when some new results appeared for the HCP conference.
I read with interest the recent disclosure that several biologists
suggest they have proven Dollo's Law (that biological evolution is irreversible, a 1-way path through genetic change and time) is at the very least not perfect and perhaps may simply be wrong.
Never having taken a biology course much less one on evolutionary theory I can't say I know anything much about Dollo's proposition other than that he posed it over 100 years ago and that Richard Dawkins supposedly characterized it more as a statement about probabilities.
Nel 1929 Bruno Rossi, ricercatore presso l’istituto di fisica sperimentale
dell’Università di Firenze [...] intuì quella che sarebbe stata la sua ragione di vita: indagare sulla natura di questi corpuscoli ionizzanti provenienti dall’alto. Doveva realizzare un circuito che permettesse di rivelare e contare le coincidenze che si verificavano in una certa unità di tempo e realizzò uno strumento molto semplice, il circuito a coincidenze.
L’involucro dei tubi Geiger è collegato al polo negativo di una batteria da 1200 volt (non
disegnata). La scarica nei tubi genera un impulso di tensione negativa sulle resistenze da
Understanding and explaining how the Universe works has always been a ultimate goal for mankind. It is impossible to live our conscious existence without asking ourselves whether there is a meaning, a design, or if our existence is just the result of chance; and to avoid asking ourselves what happens after we die, if we will live again, and similar questions. Accepting our mortality is really hard without embracing a potential explanation, a hope, or some kind of faith.
Last week a new important paper appeared in the Arxiv: "
MSSM Higgs Boson Searches at the LHC:Benchmark Scenarios after the Discovery of a Higgs-like Particle", by M.Carena, S.Heinemeyer, O. Stal, C.Wagner, and G.Weiglein. The paper fills a void that was created after the discovery of the Higgs particle last July by the ATLAS and CMS experiments: a thorough assessment of what constraints on the allowed chunks of SUSY parameter space in the light of the existence of a neutral scalar at 125 GeV.
The technical details of Big Bang, inflationary cosmology, and selected alternative theories are on offer. Popular accounts of the big bang theory, cosmic inflation, and the creation of the universe often leave out details a consumer of science would like to know. Scholarly monographs published the old fashioned way can cost hundreds of dollars per copy, and too often are locked away in university libraries. For general public availability, I present my monograph on the cosmology of the early universe.
My physics department in Padova is not a huge place, and yet I usually fail to be aware of what goes on around, since I spend all of my time buried inside my office. This morning, though, I had to pass by a meeting room on my way in, and I thus learned of a workshop about to start. Given my interest for the topic, I decided to attend to at least part of it.
"To date, there is no evidence for SUSY particles and lower limits on the masses are more than 4 GeV for gluinos and more than 20 GeV for squarks and sleptons."
D.H. Perkins, "Introduction to High-Energy Physics", 3rd ed., Addison-Wesley 1987.
CMS is one of the two huge detectors built to study the high-energy collisions of protons produced by the Large Hadron Collider at CERN. As all previous collider detectors, CMS is a redundant multi-purpose collection of dozens sub-detector components, which use different physics mechanisms to detect everything that comes out of the collision point, from protons to muons to photons, neutrinos (using the energy imbalance in the calorimeters), neutral hadrons.
Today I spent the better part of the afternoon in the company of 150 high-school students at the Liceo Fermi in Padova, giving a seminar on particle physics in the context of a project called "Masterclasses" which has been active since 2005 and is a big success.
The project aims at students in the last years of their high school and attempts to involve them in the experiments undergoing at the CERN laboratories. Sets of lectures on particle physics and cosmology at the schools are followed by a "hands-on" session at the Physics Department, where students are taught and then tested in recognizing heavy particle decays from event displays.
