||6 THE THIRTY-THIRD ANNUAL REYNOLDS LECTURE revision of common sense? That is, how widely is the scrap heap of physics known? C. P. Snow's famous Rede lecture "The Two Cultures and the Scientific Revolution"1 given at Cambridge University in 1959 drew attention to this situation in a way which has excited much discussion, some of it very acrimonious.2 Snow characterized the communications gap by considering extremes in the scientist and non-scientist groups, and put the issue colorfully: "Greenwich Village talks precisely the same language as Chelsea, and both have about as much communication with M.I.T. as though the scientists spoke nothing but Tibetan." The era of the great generalists who tried to span both worlds seems to be past. Alexander von Humboldt, who was a botanist, geologist, diplomat, physiologist, astronomer, meteorologist, assessor of mines, geographer, philosopher, explorer and who at 76 began a work on the whole cosmos, is sometimes pointed out as the last man who tried to include all knowledge as his field. Today such a task seems so immense that a suspicion of the crackpot hangs about anyone attempting it. There has grown up a rather clean split between the scientists and the non-scientists. Although this anomaly has been talked about a good deal, the recognition of its consequences is an area that has by no means been exhausted; the whole situation is of sufficient importance to warrant continued discussion. In describing the communication gap there are two aspects that are worth emphasizing: it is lopsided and semipermeable. The gap is lopsided in that the groups it isolates from one another are of unequal sizes. There are vastly more non-scientists than scientists. Misunderstood and misunderstanding minorities are no rarity, so we might simply dismiss the scientific community as a more or less crank minority, cut off to its own detriment from the mainstream by the communication gap. It is not surprising that few scientists would take this view. Scientists have a strong streak of evangelism in them. They tend to believe that if the few scientists occupy an ivory tower, then the many non-scientists occupy an ivory ghetto. The gap between tower and ghetto is also semipermeable. By this, I mean that the gap is more impenetrable one way than the other. The flow of information across the gap tends to be asymmetric, with less coming out from the scientific community than goes in. It is typically easier for the non-scientist to explain his work to the scientist than the other way around. The caricature scientist-marginally literate, technically overtrained and otherwise undereducated - is less frequently met than his opposite number, the caricature scientific humanist. We give a sort of lC. P. Snow, The Two Cultures: and a Second Loo\ (Mentor Book, 1964). 2 F. R. Leavis, Two Cultures? The Significance of C. P. Snow (London: Chatto and Windus, Ltd., 1962; New York: Pantheon Books, 1963).