Science is a personal activity. With very few exceptions, scientists throughout history have plied their craft not through a lust for glory or material reward, but in order to satisfy their own curiosity about the way the world works. Some, as we have seen, have taken this to such extremes that they have kept their discoveries to themselves, happy in the knowledge that they have found the solution to some particular puzzle, but feeling no need to boast about the achievement. Although each scientist – and each generation of scientists – exists and works in the context of their time, building on what has gone before with the aid of the technology available to them, it is as individual people that they make their own contribution. It has therefore seemed natural to me to use an essentially biographical approach to the history of science (at least, for my first attempt at such a history), in the hope of teasing out something of what makes a scientist tick, as well as revealing how one scientific advance led to another. I am aware that this is not an approach that is much favoured by historians today, and that any professional historians who have read this far may accuse me of being old-fashioned, or even reactionary. But if I am old-fashioned, it is because I choose to be so, not because I am unaware that I am out of step. I am also aware that there are almost as many approaches to the study of history as there are historians, and each approach can shed light on the subject. Few, if any, historians would claim that one person’s view (or interpretation) of history reveals ‘the’ truth about history, any more than a single snapshot of a human being reveals everything about that person. But perhaps there is something about my own approach to the history of science which may provide food for thought even for the professionals.
Although the process of doing science is a personal activity, science itself is essentially impersonal. It involves absolute, objective truths. A confusion between the process of doing science and science itself has led to the popular myth of the scientist as a cold-blooded, logical machine. But scientists can be hot-blooded, illogical and even mad while still pursuing the search for ultimate truth. By some criteria, Isaac Newton was insane, both in his single-minded obsession with a succession of interests (science, alchemy, religion) and in the intensity of his personal vendettas, while Henry Cavendish was decidedly odd. So it is important to make the distinction between what is subjective, and therefore open to debate, in the present volume and what is objective and unarguably true.
I do not claim that this is the last word on the history of science – no single volume could be. It is subjective, like all histories; but it is written from the perspective of someone who has been involved professionally in scientific research, not as a professional historian, which has both advantages and disadvantages. The most important insight this provides, as I hope the book makes clear, is that I reject the Kuhnean idea of ‘revolutions’ in science, and see the development of the subject in essentially incremental, step-by-step terms. The two keys to scientific progress, it seems to me, are the personal touch and building gradually on what has gone before. Science is made by people, not people by science, and my aim has been to tell you about the people who made science, and how they made it. Closely related to this view of science is the idea that science is to some extent divorced from the economic and social upheavals going on in the world at large, and also that it really is about a search for objective truth.
Historians or sociologists who have no training in or experience of scientific research sometimes suggest that scientific truth is no more valid than artistic truth, and that (to put it crudely) Albert Einstein’s general theory of relativity might go out of fashion just as much of the painting done by Victorian artists later went out of fashion. This is absolutely not so. Any description of the Universe that supercedes Einstein’s theory must both go beyond the limitations of that theory and include all the successes of the general theory within itself, just as the general theory includes Newton’s theory of gravity within itself. There will never be a successful description of the Universe which says that Einstein’s theory is wrong in any of the areas where it has already been tested. It is a factual, objective truth that, for example, light gets ‘bent’ by a certain amount when it passes near a star like the Sun, and the general theory will always be able to tell you how much it gets bent. At a simpler level, like many other scientific facts the inverse square law of gravity is an ultimate truth, in a way that no historical account of how that law was discovered can ever be ‘the’ truth. Nobody will ever know the extent to which Newton’s thinking on gravity was influenced by observing the fall of an apple; by the time he told the story, Newton himself might not have remembered the details correctly. But we can all know what law of gravity he discovered. So my account is personal and subjective in its interpretation of the evidence about how scientific truths were discovered; but it is impersonal and objective in describing what those scientific truths are. You may or may not agree with my opinion that Robert Hooke was maligned by Newton; but either way you would still have to accept the truth of Hooke’s law of elasticity.
If a specific example is needed of the inverse argument, the way scientific truth cannot be distorted to fit the way we might want the world to be, it is only necessary to point to the distortion of the study of genetics under the Stalinist regime in the USSR half a century ago. Trofim Denisovich Lysenko (1898–1976) gained great favour and influence under that regime because his ideas about genetics and heredity offered a politically correct view of the biological world, while the Mendelian principles of genetics were regarded as incompatible with the principles of dialectical materialism. They may well be; but the fact remains that Mendelian genetics provides a good description of how heredity works, while Lysenkoism does not – and this had disastrous repercussions at a very practical level through Lysenko’s influence on Soviet agricultural practice.
One of the strangest arguments that I have seen put forward – apparently seriously – is that using a word such as ‘gravity’ to describe the cause of the fall of an apple from a tree is no less mystical than invoking ‘God’s will’ to explain why the apple falls, since the word ‘gravity’ is just a label. Certainly it is – in the same way that the words ‘Beethoven’s Fifth’ are not a piece of music, but only a label which indicates a piece of music, and an alternative label, such as the Morse code symbols for the letter V, could just as easily be used to indicate the same piece of music. Scientists are well aware that words are merely labels which we use for convenience, and that a rose by any other name would smell as sweet. That is why they deliberately choose to use a nonsense word, quark, as the label for a fundamental entity in particle theory, and why they use the names of colours (red, blue and green) to identify different kinds of quark. They do not suggest that quarks really are coloured in this way. The difference between the scientific description of how apples fall and the mystical description of how apples fall is that, whatever the name you ascribe to the phenomenon, in scientific terms it can be described by a precise law (in this case, the inverse square law) and that the same law can be applied to the fall of an apple from a tree, the way the Moon is held in orbit around the Earth and so on out into the Universe. To a mystic, there is no reason why we should expect the way an apple falls from a tree to bear any relation to, say, the way that a comet moves past the Sun. But the word ‘gravity’ is simply a shorthand expression for the whole suite of ideas incorporated in Newton’s Principia and Einstein’s general theory of relativity. To a scientist, the word ‘gravity’ conjures up a rich tapestry of ideas and laws, in the same way that to the conductor of a symphony orchestra the words ‘Beethoven’s Fifth’ conjure up a rich musical experience. It is not the label that matters, but the underlying universal law, giving a predictive power to science. We can say with confidence that planets (and comets) orbiting other stars are also under the influence of the inverse square law, whether you ascribe that law to ‘gravity’ or to ‘God’s will’; and we can be sure that any intelligent beings inhabiting those planets will measure the same inverse square law, although undoubtedly they will call it by a different name from the one we use.
There is no need for me to labour the point. It is because there are ultimate truths out there that science hangs together so well. And what motivates the great scientists is not the thirst for fame or fortune (although that can be a seductive lure for the less-than-great scientists), but what Richard Feynman called ‘the pleasure of finding things out’, a pleasure so satisfying that many of those great scientists, from Newton to Cavendish and from Charles Darwin to Feynman himself, have not even bothered to publish their findings unless pressed by their friends to do so, but a pleasure that would hardly exist if there were no truths to discover.