BTW, I learned about this experiment while reading about Coulomb's law on wikipedia:
http://en.wikipedia.org/wiki/Coulomb's_law#Tentative_evidence_of_infinite_speed_of_propagation Harry On Sat, Feb 15, 2014 at 1:44 AM, H Veeder <hveeder...@gmail.com> wrote: > 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 Li enard-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 Li enard-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. >
