On the Trouton-Noble Experiment

The experiment of F. T. Trouton and H. R. Noble to detect the motion of the earth through the ether by means of electromagnetic torque on a charged, suspended, parallel-plate capacitor is reexamined. No previous explanation of the null result appears to be satisfactory because, as is shown herein, conventional relativistic electrodynamics predicts that the total electromagnetic field energy of the capacitor is different in the two orientations. Therefore, this combination predicts that the result should not be null. A new explanation of the null result is offered, based on a new equation for the energy density $dU/dV$ in the electric $E$ and magnetic $H$ fields of a classical macroscopic charged body with a uniform speed $β$ in units of the speed of light. This new equation $dU/dV = (E2−H2)/8π(1−β2)$⁠, in Gaussian units in vacuo, predicts that the total electromagnetic field energy of the capacitor is independent of its orientation in agreement with the null result of Trouton and Noble.