Here is a November 2012 paper about an experiment which tentatively shows that electric fields seem to propagates rigidly, i.e. with infinite speed. Although it hasn't been published in a peer reviewed journal yet, given the fact that the observation challenges Special Relatively, one would have expected this paper to zip around the blogosphere and make its way into mainstream media. Perhaps the recent mistaken claim of faster-than-light neutrinos at a noteworthy facility - namely CERN - has dampened interest in such challenging observations.
Harry -------------- http://arxiv.org/abs/1211.2913 Measuring Propagation Speed of Coulomb Fields A.Calcaterra, R. de Sangro, G. Finocchiaro, P.Patteri, M. Piccolo, G. Pizzella (Submitted on 13 Nov 2012) Abstract The problem of gravity propagation has been subject of discussion for quite a long time: Newton, Laplace and, in relatively more modern times, Eddington pointed out that, if gravity propagated with finite velocity, planets motion around the sun would become unstable due to a torque originating from time lag of the gravitational interactions. Such an odd behavior can be found also in electromagnetism, when one computes the propagation of the electric fields generated by a set of uniformly moving charges. As a matter of fact the Li\'enard-Weichert retarded potential leads to a formula indistinguishable from the one obtained assuming that the electric field propagates with infinite velocity. Feynman explanation for this apparent paradox was based on the fact that uniform motions last indefinitely. To verify such an explanation, we performed an experiment to measure the time/space evolution of the electric field generated by an uniformerly moving electron beam. The results we obtain on such a finite lifetime kinematical state seem compatible with an electric field rigidly carried by the beam itself. Conclusions Assuming that the electric field of the electron beams we used would act on our sensor only after the beam itself has exited the beam pipe, the L.W. model would predict sensors responses orders of magnitudes smaller than what we measure. The Feynman interpretation of the Lienard-Weichert formula for uniformly moving charges does not show consistency with our experimental data. Even if the steady state charge motion in our experiment lasted few tens of nanoseconds, our measurements indicate that everything behaves as if this state lasted for much longer. To summarize our fi nding in few words, one might say that the data do not agree with the common interpretation of the Lienard-Weichert potential for uniformly moving charges, while seem to support the idea of a Coulomb field carried *rigidly* by the electron beam. We would welcome any interpretation, diff erent from the Feynman conjecture or the instataneous propagation, that will help understanding the time/space evolution of the electric field we measure.
