This book, written for nonspecialists, discusses the apparent conflict between relativity and quantum mechanics, concentrating particularly on what Einstein called "spooky action at a distance." The author proposes a resolution based on a causal interpretation introduced by Louis de Broglie and elaborated by David Bohm. He shows that one can introduce a "medium" or
"aether" in a manner consistent with both relativity and quantum theory, and that allows one to unify the two theories via the identification of circularly causal processes at their core. The mathematics is kept simple, making the discussion accessible to a wide audience. Several crucial experiments are discussed in detail.