Which of the following statements do you think is more applicable to science? (1) "History is more or less bunk" [Henry Ford]; (2) "If men could learn from history, what lessons it might teach us!" [S.T. Coleridge].
How would most scientists answer? Some—such as those involved in taxonomy—might opt for the second alternative, but I suspect a majority would prefer the first. Yet it is difficult to avoid all history in science.
For example, astronomers often use a graph known as the Hertzsprung-Russell diagram. This is not a plot of Hertzsprung against Russell—as one of my students once asserted—but of the brightness of a star against its surface temperature. The historical query here is not who Hertzsprung and Russell were, but why they plotted the graph in such a way. The values of brightness on the vertical axis increase in the usual way, with largest values at the top and smallest at the bottom. But the values of the surface temperature increase from right to left, instead of going from left to right as usual. Why? The answer is tied up with history, more especially with confused surface temperature measurements at the beginning of this century. Being lazy, astronomers have never gotten around to correcting the mistake.
Astronomy students have been curious enough to query the oddity of the Hertzsprung-Russell diagram. Similarly, most physics students wonder briefly about the units they use. Who were Weber and Oersted, anyway? But there is no need to know the answers to such questions in order to do the science.
However, any science that has an observational, as distinct from an experimental, component, can actually impose the need to do some historical digging. Volcanic eruptions are a case in point. The destruction of an Indonesian island Krakatau by a volcanic explosion in 1883 was on such a scale that its effects were observed in great detail all around the globe. The data have formed the standard for comparison ever since: new analyses of the Krakatau observations are still appearing.
In a similar way, data collected in the past for epidemiological studies may require reanalysis in the light of new information. Snow's classic investigation into a 19th century cholera epidemic is a good example. Snow plotted cholera data from one part of London on a street map, and so deduced that water from one particular street pump was to blame for the epidemic. There has been some doubt down the years whether the situation was as clear-cut as Snow imagined, so his data have been reanalyzed more than once.
Backward looks of this sort may not usually be required in a purely experimental science, but does mean that such a science can be totally ahistorical? Reasonably enough, many scientists are not too worried about the depth of their background knowledge, so long as their experiments work all right. But at intervals, basic confusions arise that do require even hardheaded pragmatists to sit back and reconsider the past.
For example, current debate over the interpretation of certain quantum mechanical experiments has renewed interest in arguments between Bohr and Einstein many years ago. Einstein himself was the heir of a similar debate. Ernst Mach examined the basis of classical mechanics about a century ago. His aim, he said, was, "to clear up ideas, expose the real significance of the matter and get rid of metaphysical obscurities." This retrospective study provided an important part of the background to relativity theory.
An Accidental Profundity
The scientists described in these passages are now leaders in their fields, and maybe the pigeons of historical ignorance are coming home to roost. One noticeable development of recent years has been the appearance of historical sections in a range of scientific societies.
Perhaps this does suggest that the scientific community is accepting again the need to reflect on things past. In a recent examination, one of my students wrote: "Galileo pointed his telescope at the heavens, which he had invented." Twenty years ago I would have reflected on his bad grammar: now I reflect on his accidental profundity.