Physics
A new preprint is out in the arxiv today, detailing the results of a new analysis of neutrino speeds performed by the OPERA collaboration using proton spills of the CNGS beam produced during dedicated runs in May this year.
If you have missed the whole saga of superluminal neutrinos last Fall (on which planet were you then ?) it is hard for me to fill you in, given my dislike for rewriting the same things over and over again beyond the decency line. Maybe the best advice I can give you is to search for "OPERA" or "superluminal neutrino" in the search box on the top right. That way you should…
Even in deep space, atoms feel the the cosmic microwave background left over by the Big Bang. The cosmos is filled with electromagnetic interactions that show atoms they are not alone. Stray electric fields, like from a nearby electronic device, will also slightly adjust the internal energy levels of atoms, a process called the Stark effect.
Even the universal vacuum, presumably empty of any energy or particles, can very briefly muster virtual particles that buffet electrons inside atoms, further shifting their energies; this form of self-interaction is known as the Lamb shift.
A new…
The conceptual design report of the Mu2E experiment at Fermilab is out in the arxiv for you to browse. Mind you - it is a rather thick document, 562 pages in all, so if all you have is 15' of lunch break you have better try something lighter.
The experiment aims at searching for muon decays to electrons in the field of heavy nuclei (tungsten or aluminum, as far as I understand from a quick browsing). Leaving aside the nucleus, I would bet that if you have a basic knowledge of the standard model of fundamental interactions, gathered by reading standard undergraduate books such as the Perkins…
Black holes are again hitting the headlines. Another record super massive black hole has been unveiled. This time it is galaxy NGC 1277 at the center of which a true monster is discovered to be lurking. Dutch astronomer Remco van den Bosch and co-workers weighed the black hole at the center of this galaxy. They did so by interpreting the stellar kinematics from velocity dispersion measurements obtained with the Marcario Low Resolution Spectrograph on the Hobby-Eberly Telescope at the McDonald Observatory in Austin, Texas. They came to the conclusion that the giant weighs in at 17 billion suns…
"While looking for the decay pi+ -> e+ nu_e, we focused all our attention on reducing backgrounds, since a prior experiment had set a limit at the level of 10^-6 on the branching ratio. When we heard that an experiment at CERN had seen a signal around 10^-4 I switched from delayed to prompt. The signal was right there, and could have been seen on the first day."Burton Richter, quoted in J. Klein, A.Roodman, "Blind Analysis in Nuclear and Particle Physics"
A reader correctly mentions that it is not exactly trivial to understand the above quote without some explanation, so here…
Update: I got a confirmation that at the latest INFN board of directors meeting the news was given that the Super-B factory to be built outside Rome is no more. Super-B joins other remarkable projects in high-energy physics -notably the SSC, the American 40-TeV super-collider to be built in Texas, and killed by Congress in 1993- in the dust bin.
With this move the Italian government shows again how little they care for basic research in Italy, and provides further fuel to the escape of bright researchers to other countries.
Now the funny thing (yes, as if there was anything to laugh about) is…
Halliday |
We ended the second article in this series with the audacious claim that we have obtained the METRIC.1 Quite frankly, I expected to hear a howl of protest to my brazen assertion that we had actually gotten so far. We certainly hadn't obtained anything quite like the usual matrix or tensor form of a metric, or even a "line element", nor had we seen how this has any relationship to the usual "strangeness" of the Special Theory of Relativity.
It is the issues/questions of the metric, its relationship to the inner or dot product, and what forms it may take that we shall address in…
Halliday |
We ended the second article in this series with the audacious claim that we have obtained the METRIC.1 Quite frankly, I expected to hear a howl of protest to my brazen assertion that we had actually gotten so far. We certainly hadn't obtained anything quite like the usual matrix or tensor form of a metric, or even a "line element", nor had we seen how this has any relationship to the usual "strangeness" of the Special Theory of Relativity.
It is the issues/questions of the metric, its relationship to the inner or dot product, and what forms it may take that we shall address in…
The top quark is the heaviest of the six known hadron constituents, discovered at the Fermilab Tevatron collider in 1995. Because of its quite large mass -over forty times more than the second-heaviest bottom quark- and because of a few additional interesting properties, the top quark has stimulated in the past two decades a large amount of theoretical work, well matched to the Tevatron investigations.
In fact, one of the explicit goals of the CDF and DZERO experiments for Run II of the Tevatron, which lasted from 2002 to 2010, was to study extensively the top quark both as a standard…
vongehr |
Einstein infamously said, and he said so many times, that god does not play dice. He said this in order to refute indeterminism, and therefore, we cannot say that he was correct: The meaning he intended to communicate was probably wrong (depending on your definition of “god”). However, the most relevant meaning of his statement is self-evidently true: Randomness (indeterminism) is not satisfyingly explained by merely postulating some more mystical randomness (god’s dice).
The modern version of god throwing dice is called “genuine stochastic” behavior or…