Physics

Can plasma be beautiful?   Surely, anything can, but physicists are luckier than most because when they probe the mysteries of plasma, the fourth state of matter, they often discover phenomena of striking beauty. 

Plasmas support a large variety of waves, some familiar to all such as light and sound waves, but a great many exist nowhere else and one of the fundamental waves in magnetized plasma is the shear Alfvén wave, named after Nobel Prize winning scientist Hannes Alfvén, who predicted their existence.
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<![endif]-->Microwaves are a low frequency light, at least compared to visible light, say, or ionizing radiation like gamma rays. Thus, microwaves are quite harmless. A microwave oven baths the food in an oscillating electro-magnetic field. Molecules with permanent electrical dipole moments wiggle in the field and thus heat up the food.
As beautiful as they get, or even more so. It is hard to express the beauty of the event that the CMS collaboration published today. CMS, which stands for "compact muon solenoid", is one of the two main detectors operating at the CERN Large Hadron Collider (the other is ATLAS). The duo is seeking evidence for the Higgs boson, the only elementary particle predicted by the Standard Model that still awaits to be discovered.
Giorgio Chiarelli is a particle physicist. His research activity has been based largely at the Fermi laboratory near Chicago, US, at the CDF experiment. In 1994-96 he actively participated in the discovery of the top quark and in the first measurements of that particle's properties. Later, after directing the construction of a part of the new CDF detector, he moved its research interests toward the search for the Higgs boson. Currently he is a INFN research director in Pisa, where he leads the CDF-Pisa group. In the most recent years he dealt with problems connected with the communication of science.
The ATLAS collaboration has just released an important study of the sensitivity to a standard model Higgs boson. For the first time precise predictions are made for LHC running at a centre-of-mass energy of 7 TeV (but also 8 and 9 TeV are considered, given the possibility that next year the energy is bumped up a bit), and for most of the sensitive channels together.

The public document is long and detailed, and I have no time to discuss its intricacies with you here, nor do I believe that you would actually want me to. But I do want to discuss one of the most significant figures in the note. It is shown below.

Special Guest Post From A Far Boundary Of Our Universe

By Richard P. Flatman


"I call our world Flatland, not because we call it so, but to make its nature clearer to you, my happy readers, who are privileged to live in Space."

This is how my great-grandfather, Albert Square, started his memoirs. Memoirs he wrote in solitary confinement. Years later he died, still imprisoned and alone, and unaware that his ideas slowly but steadily started to change the views and imagination, not only of his fellow Flatlanders, but also of you Spacelanders.* 
 
News from the LHC: the integrated proton-proton luminosity at 7 TeV centre-of-mass energy has generously passed the mark of 40 inverse picobarns yesterday. The CMS experiment alone has integrated over 42 inverse picobarns, as shown in the graph below (the blue curve shows the data collected by CMS, the red one the data produced by the LHC).


In one description, an observer falls freely through empty space, in another one, she hits a surface smack on, yet both descriptions are completely equivalent. This example for a duality in modern physics was explained the last time in this series. There we saw that a black hole can also be described by a string theoretical membrane at the event horizon. The observer cannot escape the black hole because she literally gets stuck to the black hole’s event horizon, glued to it via strings.
Physical reality is composed of properties like distance, duration, velocity, area, volume, mass, energy, and temperature. To quantify these properties you need to measure them. And the act of measuring boils down to comparing against an agreed yardstick, a unit of measurement such as a foot, a gram, etc. 

Do you need a dedicated yardstick for each quantifiable property?

Would the answer to this question be 'yes', then physics as we know it, would not be possible. We would not be able to relate the various properties to each other, physics laws would not exist. Fortunately, the answer to the question is a clear 'no'. We need far fewer units than one might expect based on the number of physical properties. 
The CMS experiment has just released a new result which excludes the possibility that quarks have a substructure at energy scales below 4 TeV. The result comes from the analysis of just a handful of inverse picobarns of collision data -2.9 to be precise- and shows excellently just how well suited are the LHC collisions for this business. The limit is extended by over one TeV above the former result of the Tevatron experiments, and some 600 GeV above the results of the ATLAS collaboration, who also recently reported on their search for of quark compositeness in 7 TeV collisions, finding a limit at 3.4 TeV.