Chapter 3 Darkening perplexities
At the time at which modern quantum theory was discovered, the physical problems that held centre stage were concerned with the behaviour of atoms and of radiation. This period of initial discovery was followed in the late 1920s and early 1930s by a sustained and feverish period of exploitation, as the new ideas were applied to a wide variety of other physical phenomena. For example, we shall see a little later that quantum theory gave significant new understanding of how electrons behave inside crystalline solids. I once heard Paul Dirac speak of this period of rapid development by saying that it was a time ‘when second-rate men did first-rate work’. In almost anyone else’s mouth those words would have been a putdown remark of a not very agreeable kind. Not so with Dirac. All his life he had a simple and matter-of-fact way of talking, in which he said what he meant with unadorned directness. His words were simply intended to convey something of the richness of understanding that flowed from those initial fundamental insights. This successful application of quantum ideas has continued unabated. We now use the theory equally effectively to discuss the behaviour of quarks and gluons, an impressive achievement when we recall that these constituents of nuclear matter are at least 100 million times smaller than the atoms that concerned the pioneers in the 1920s. Physicists know how to do the sums and they find that the answers continue to come out right with astonishing accuracy. 39
