To-day more than ever it has become clear to everyone what an important rôle science plays in the modern world. And of all the sciences it is physics that has shown itself to be most successful. Physics is the most advanced of the natural sciences. The methods and techniques of physics are more accurate and more reliable than those of any other science, and its results have been strongly confirmed by experience. For this reason physics is best fitted to serve as an example of the ideas of modern science.
The material revolution science has brought about is felt everywhere; but the intellectual revolution, the change in ideas and concepts, has not penetrated far into every-day life. The intellectual climate in which we live lags behind the material or technical climate created by the discoveries of science and the inventions of industry. We may have heard the latest facts, but do we understand them? Can we achieve the intellectual integration which an understanding of science requires? Some years ago Einstein complained that ' . . . many scientists were unable to grasp the meaning of the (relativity) theory itself; all they could understand were its consequences within their special field'. If this criticism holds true even for the average scientist, how much more does it apply to the man in the street?
It may be no exaggeration to say that the intellectual methods, the thinking habits which science requires, are largely unknown even to the educated layman. So far as physics is concerned we may doubt whether the average man has caught up with Galileo and Newton; and there are many who have not yet grasped what Aristotle knew two thousand years ago. People learn by rote certain results of science as applied to every-day life; they know how to manipulate gadgets; they acquire skills. It would be wrong to underestimate the value of this practical knowledge; but it is too limited. Isn't it strange that a man should know how to run a machine, and yet not know what 'makes it tick' ? We need to make