Abstract

We introduce a principle of equivalence for the electromagnetic field: A non-inertial system with an acceleration is equivalent to a certain electromagnetic field, in which the ratio of charge to mass is the same. From this principle can be derived an electromagnetic general relativity theory (GRT) whose formulations are completely analogous to Einstein's GRT. In the electromagnetic case, the field is regarded as a type of curved space-time for charged bodies, where space-time is separated into many layers, the curvatures of which are different for different ratios of charge to mass. In a general case, electrodynamics can be obtained from this theory. But its high-order approximation will deviate from the present electromagnetic theory. Therefore, we discuss the four possible tests for this theory and some notable problems. Finally, the most universal principle of extended equivalence and the extended GRT are proposed.