"If physics is too difficult for the physicists, the nonphysicist may wonder whether he should try at all to grasp its complexities and ambiguities. It is undeniably an effort, but probably one worth making, for the basic questions are important and the new experimental results are often fascinating. And if the layman runs into serious perplexities, he can be consoled with the thought that the points which baffle him are more than likely the ones for which the professionals have not found satisfactory answers."