Most precise test of Lorentz symmetry for the photon finds that the speed of light is indeed constant September 15, 2015 by Lisa Zyga feature Please Register or Log in to view the hidden image! (Left) Photo of the orthogonal sapphire crystal mount, with (right) simulations of the electromagnetic resonant mode patterns. A frequency variation in the resonance would indicate a variation in the speed of light. Credit: Stephen R. Parker, The University of Western Australia Read more at: http://phys.org/news/2015-09-precise-lorentz-symmetry-photon-constant.html#jCp extract: Now in a new paper, physicists have reported the most precise test to date of Lorentz symmetry for the photon by looking for variations in the speed of light, but have found no violations. The study, by Moritz Nagel at the Humboldt-University of Berlin, Stephen Parker at The University of Western Australia, and their coauthors, is published in a recent issue of Nature Communications.
Those tests of Lorentz symmetry seem to be getting a workout recently, a reflection of just how important such work is to physics. "Since the precision of the new test (10-18) is an order of magnitude better than that of previous tests of Lorentz symmetry of the photon, it does allow the scientists to improve the bounds on the nine rotational and boost isotropies of the speed of light by a factor of four." Some eye-popping precision there. Relativity and the invariance of the speed of light wins again. More experiments to come. All good.
More detailed information about the experiment can be found here: http://www.nature.com/ncomms/2015/150901/ncomms9174/full/ncomms9174.html The experiment continued for over a year and compensation of oscillator stability for the SME (Sun-Moon-Earth) accelerations were taken into account. The next round of experiments will feature improved microwave oscillator frequency stability and shielding.
