Vibration pressure hypothesis for electric repulsion

TWO ELECTRIC charges of the same sign have been observed, since the early experiments with frictional electricity and pith balls, to repel each other. An electrified pith ball is said to have an electric field, and a second one near it lies in that field and is repelled. The mechanical force is “action at a distance,” and standard books give no description or explanation of what causes the mechanical force or what is happening between the two charges to convey the action from one to the other. Such a description is not given by saying that there is an electric field at all points between the two charges — that is merely stating that a charge placed at any of the points will be repelled, always by action at a distance. Electrostatic repulsion is thus one of the mysteries of science.