Chapter 2 The Active Ether

Duringmost of the nineteenth century the existenceof an all-encompassing ether as a substitute for a true void was taken for granted. According to the successful electromagnetic ether theory based upon Maxwellian electrodynamics, the ether was endowed with energy and hence very different from nothingness. Oliver Lodge thought that its energy density was enormous, about 1033 erg cm−3. The active ether of the fin-de-siècle period was in some respects surprisingly similar to the later quantum vacuum, yet it was based fully on classical physics.