Beautiful new experiment verifies (yet again) that quantum mechanics is weird

A new experiment carried out in the Netherlands has confirmed the “spooky action at a distance” that is a central feature of quantum mechanics.  There have been several such confirmations, going back to the early 1980s, but this is is the first one that simultaneously closes all the loopholes that might arise.  It may therefore be the final blow to the idea — championed by Einstein and Bell, among others — that quantum mechanics is incomplete and there might be local “hidden variables.”

The preprint version of the paper is available here.

The Coldest Place in Westerville

Last week Dr. Reinhard and his students detected ultracold rubidium atoms in a magneto-optical trap for the first time. The atoms, seen below with an infrared sensitive camera, have a temperature of about 100 micro Kelvin, or about a million times colder than room temperature. For reference, the surface of the sun is only about 20 times hotter than room temperature. IMG_0408

First collisions at 13 TeV as the Large Hadron Colllider restarts


On May 21, 2015 proton beams were collided together in the Large Hadron Collider at the record energy of 13 TeV, as the LHC restarts after extensive upgrades over the past two years.  This is the total energy in the center-of-mass frame, so each beam contains protons of energy 6.5 TeV.  That’s about 6,500 times the rest energy of a proton (roughly 1 GeV), hence the relativistic gamma factor for these protons is about 6,500.

Read the CERN article on this important milestone here.

Higgs boson paper has 5,154 authors

CMS and Atlas, the two big experimental collaborations at the Large Hadron Collider, have joined forces to produce the most accurate determination of the Higgs boson mass to date.  By combining their data sets they obtained

$$ M_H=125.09\pm0.24~GeV$$

for a relative error of about 0.2%.  The paper in Physical Review Letters describing these results has the longest author list ever: 5,154 names.  In the published version, there are 9 pages describing the research and 24 pages of authors and their affiliations.

Read the associated APS Physics Viewpoint article here.