Physics news highlighted in this week’s Nature
DOI: 10.1063/PT.4.0281
A pair of news stories featured in the latest issue of Nature could draw attention from the physics community.
Eugenie Samuel Reich’s “Physicists count on updated constants ” begins,
As cheat sheets go, it is a long one. Every four years, a task force of the Committee on Data for Science and Technology (CODATA), headquartered in Paris, releases a shorthand description of the physical world: the latest, painstaking determination of the values and uncertainties of more than 300 physical constants, from the familiar speed of light, c, to the more obscure mass of the tau lepton, τ.
The most recent figures, from 2010, were first placed online in June and announced on 19 July by the US National Institute for Standards and Technology (NIST) in Gaithersburg, Maryland. The numbers include reduced uncertainties for several key constants, which physicists say is encouraging because these will allow for better tests of theory. The more precise figures will also aid plans to redefine familiar units of measurement, such as the kelvin and the kilogram, in terms of unchanging fundamental constants rather than relying on a material object that might not be stable (as for the kilogram standard).
Reich reports that uncertainties have decreased for the fine-structure constant and for the constants named for Planck, Avogadro and Boltzmann. And she reports the belief of Terry Quinn, emeritus director of the International Bureau of Weights and Measures, that improved precision for the latter two constitutes “a boost for a proposal to rationalize the international system of standard units ... by linking four of them—the ampere, mole, kilogram and kelvin—to physical constants.”
Geoff Brumfiel’s article “Hint of Higgs, but little more ” updates progress at CERN’s Large Hadron Collider in Switzerland. Nature sums it up this way in the thumbnail summary: “No signs of exotic new physics have yet emerged from Europe’s giant particle accelerator.” Brumfiel begins:
When its experiments started in earnest earlier this year, many scientists hoped that the world’s most powerful collider would turn up new particles, additional dimensions and perhaps even a small black hole or two. But beyond a handful of unusual events, the latest data from the Large Hadron Collider (LHC) are frustratingly ordinary.
For more than a decade, theorists have hoped that the LHC might be powerful enough to generate previously unseen phenomena that would shake the sturdy standard model of particle physics to its core.
But the latest findings from the machine couldn’t raise even a tremor inside the main auditorium of the Alpexpo centre in Grenoble, [France,] where scientists gathered last week for the International Europhysics Conference on High Energy Physics. In one session, Helen Hayward, an experimental physicist at the University of Liverpool, UK, flashed her data from the LHC’s ATLAS detector onto the screen, along with the standard model’s predictions of the particles that should have emerged from the smash-up. Her observations matched the predictions so perfectly that many of the numbers were identical.
Brumfiel cites one possible exception: “excess events” amounting to hints “of a few extra particles corresponding to something new” at energies around 140 GeV. If “the signal grows stronger as data accumulates,” he reports, “then it could be a sign of the Higgs boson.” He closes by observing that “over its 20-year lifetime, the collider could still turn up something entirely new,’ but that many LHC researchers have “admitted disappointment that nothing unusual has popped up inside the machine so far.”
Steven T. Corneliussen, a media analyst for the American Institute of Physics, monitors three national newspapers, the weeklies Nature and Science, and occasionally other publications. His reports to AIP are published in ‘Science and the media.’ He has published op-eds in the Washington Post and other newspapers, has written for NASA’s history program, and is a science writer at a particle-accelerator laboratory.
