Physics

A really interesting piece of news comes from the CERN laboratory today. The CMS experiment has detected a handful of Z boson decays in events featuring the collision between heavy ions, accelerated to energies of hundreds of GeV per nucleon. Heavy ion collisions are not the reason why the CMS detector was built. When two nuclei of lead or gold collide at very high energy, the result involves simply too much information for a subnuclear physicist's taste. Already two protons colliding head-on are much more than a particle physicist would like to have: in fact, what one observes in a proton-…

Here I will explain the difference between matter, anti matter, dark matter, and negative matter in a concise and understandable way.   I have seen confusion pop up in various online forums and comments on the recent announced trapping of an anti atom by CERN.  The first thing to know is that for a physicist there are four fundamental forces of nature which are always at work.  These are the familiar Gravity and  Electromagnetism, as well as the generally unfamiliar strong and weak atomic forces.   The atomic forces work on the length scale of atoms, Electromagnetism…

Scientific American features an excellent article by Garrett Lisi and James Owen Weatherell, with title "A Geometric Theory of Everything". It is a rather clear explanation of the ideas behind the recent articles published by Lisi on the E8 group and how this exceptionally rich mathematical structure could embed the representation of all particles and forces of nature. Group theory is a fascinating branch of mathematics, and its connection with fundamental physics has kept becoming stronger with time, ever since the neutron was discovered in the early thirties. The proton and the neutron were…

Atoms of antimatter have been trapped and stored for the first time by the ALPHA collaboration, an international team of scientists working at CERN.  ALPHA stored atoms of antihydrogen, consisting of a single negatively charged antiproton orbited by a single positively charged anti-electron (positron). While the number of trapped anti-atoms is far too small to fuel an matter-antimatter reactor (sorry, "Star Trek" fans), this advance brings precision tests of the fundamental symmetries of nature a little closer. Measurements of anti-atoms may reveal how the physics of antimatter differs…

The DZERO collaboration  published a few days ago the results of their search for multi-b-quark signatures of Supersymmetry in a large dataset of proton-antiproton collisions at 1.96 TeV. The possible large coupling of higgs bosons to b-quarks makes searches with many b-quark-jets worth pursuing at the Tevatron. This has in the past been a field where interesting excesses have appeared in CDF and DZERO data, (and even a source of uncontrolled rumors three years ago) although arguably the hard-to-model QCD background has always been the principal suspect of the effects. The new result by…

Many are troubled by dark energy. I will tell you first why dark energy is really crazy. Then I tell you that the crazy part is not actually the problem of dark energy, but one of basic general relativity. Many educated people are proudly critical of dark stuff, but when it comes to relativity, they do not want to be found hanging out in the crack-pot corner. In other words, my post is directed at the guys who go: “I know about relativity and agree it is more or less fine what those cosmologists did then, but this dark stuff now is going too far! Stop the wild guessing and go back to doing…

Stupid physicists, they are doomed. Spending their whole lives searching for a theory of everything, not knowing that some eighty years ago this was proven to be logically impossible.  The internet is full with sentiments like the above. Many such posts refer to Stephen Hawking's 2002 Dirac lecture Gödel and the End of Physics. With the publication of his new book 'The Grand Design', the Oracle of Cambridge is again adding to the confusion. However, due to all the fuzz surrounding a much less interesting claim by Hawking this issue has not received any attention whatsoever. What is…

The arxiv is featuring a new paper by Darien Wood, member and spokesperson of the DZERO experiment and a distinguished physicist with lots of experience in hadron collider physics. The paper is titled "The Physics Case for Extended Tevatron Running" and it is an explanation of the benefits that a Run III until 2014 will bring to our knowledge of high-energy physics. I found the paper unnecessarily taking an enthusiastic stand, overemphasizing certain aspects of the matter without trying to be objective on the big picture, and I decided to play the censor. I hope Darien does not take this as a…

The most recent issue of symmetry magazine has a feature titled, "When Muons Collide," by Leah Hesla. [Full disclosure: I have also written for symmetry.] The article lays out the need for a muon collider as well as theoretical plans for building one. In recent months many popular news outlets have described events at the Large Hadron Collider, located at the European Organization for Nuclear Research, or CERN. As a result, many people have become familiar with the term "particle collider." Despite the self-explanatory term, however, it might not be entirely clear what such a machine does. In…

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. Shear waves of various forms have been a topic of experimental research for…