The Two-Handed Engine

ciple," according to which an electron cannot simultaneously have both position and velocity. Since uncertainty pr~vails, the theory has been held to disprove the philosophical principle of determinism and thus to give a scientific basis (or the doctrine of the freedom of the will. Dr Watson dissents from this conclusion and shows, what is generally overlooked, that the new physics has merely substituted the causality of quantum mechanics for that of classical mechanics, each of which is valid in its own field. The resolution of the difficulties attendant upon determinism and free.:will cannot therefore be found in modern physics. Dr Watson discusses or alludes to over two hundred physical principles, facts or philosophical ideas, some of which are very abstruse, so that his book, even though brief, possesses a wealth of material. It is not always easy reading, and it seldom evades a difficulty. Able and often brilliant it measurably accomplishes its purpose, which is the understanding of physics, and that is the nature of the physical world.