What do clocks have to do with it?
- The Physicist and the Philosopher: Einstein, Bergson and the Debate That Changed Our Understanding of Time by Jimena Canales
Princeton, 429 pp, £24.95, May 2015, ISBN 978 0 691 16534 9
Fama is a fickle goddess. In the early decades of the 20th century the French philosopher Henri Bergson was a worldwide celebrity, ranked as a thinker alongside Plato, Socrates, Descartes and Kant. William James thought Bergson’s work had wrought a Copernican revolution in philosophy. Lord Balfour read him with great care and attention; Teddy Roosevelt went so far as to write an article on his work. People climbed ladders merely to catch a glimpse of the great Frenchman through the windows of university halls, and Parisian society figures sent their servants ahead to secure seats at his lectures. When he gave a talk at City College in New York in 1913, so many people turned up in the hope of hearing him that the Manhattan traffic was brought to a standstill.
Yet who now reads Bergson, apart from a few lonely specialists? He is remembered by Proust scholars – Proust was Bergson’s cousin-in-law, and the best man at his wedding – since A la recherche du temps perdu was said to have been influenced by Bergson’s theory of time. But very few contemporary philosophers consider him of any importance, and it would be a rare schoolboy nowadays who would know his name. Albert Einstein, on the other hand, is as famous today as he was when his theory of relativity first set the public’s imagination alight. His status as the greatest scientist since Newton was acknowledged in 1920 when Arthur Eddington presented the results of observations made during a total eclipse of the sun the previous year, which showed that light does indeed ‘bend’ in the vicinity of stars and planets, thus confirming the general theory of relativity.
On 6 April 1922, Bergson and Einstein met in Paris, under the auspices of the Société française de philosophie, and engaged in a debate on the nature of time. The occasion, attended by a number of eminent scientists and philosophers, had been intended, as Jimena Canales tells us, ‘as a cordial and scholarly event’; as it transpired, although much scholarship was on display, the supply of cordiality quickly ran out. From the outset Einstein was at a disadvantage, since the debate was conducted in French, a language of which he had only a shaky grasp. For all his renown, he needed to emerge as the victor of that day’s clash of the titans. The world at large may have believed that the Newtonian order had been overturned and that from now on everything was ‘relative’, but there were many who were still sceptical of the implications of relativity, not only philosophers but scientists too, among them even some of Einstein’s most enthusiastic admirers. And when Einstein received the Nobel Prize, a few months after the debate with Bergson, it was given not for his two revolutionary papers on relativity – in 1905 and 1915 – but for his work on the photoelectric effect. There was an added sting when the president of the Nobel Committee, presenting the prize, remarked: ‘It will be no secret that the famous philosopher Bergson in Paris has challenged this theory [of relativity].’
The point in question was whether Einstein’s theory was a description of reality as it is, or just another hypothesis – although a hypothesis of genius – that fitted the facts more neatly and in a more aesthetically pleasing fashion than any theory that had gone before, including Newton’s mechanistic conception of the world and how it works. This is a sensitive issue for cosmologists. The stargazers of old had a nice formulation whereby they spoke of this or that theory of the heavens ‘saving the phenomena’: that is, agreeing with what was to be observed of planetary motions, but not necessarily claiming to be a direct representation of what actually happens out there in those infinite spaces the thought of which so disturbed Pascal’s peace of mind. Hence, for instance, the Egyptian astronomer Ptolemy (d. 168 ce) accounted for the anomalies of planetary orbits as viewed from Earth by adding epicycles to them, and epicycles to epicycles, so that in his model of the world the planets were made to perform impossibly complicated loop-the-loops. All the same, Ptolemy’s treatise the Almagest remained every astronomer’s handbook throughout the Middle Ages and up to, even beyond, Copernicus.
The great instauration in cosmology was spurred on by Galileo, whom we might designate the inventor of technology, and reached its apotheosis in Newton, the first real scientist, as we understand the term nowadays (the old name for science was ‘natural philosophy’), and the one who claimed to be offering not merely a plausible model of the world, but a precise and exact account of how things are. ‘Hypotheses non fingo,’ he haughtily insisted: ‘I feign no hypotheses.’ The clockwork universe that he postulated had been in the first place wound up and set going by God, and would continue to work in a wholly predictable, calculable and orderly fashion until the Last Trump should sound.
Newton’s was the only portrait that Einstein kept on the wall above his desk in his office in Princeton. It is popularly imagined that Einstein completely overthrew Newton, but as Abraham Pais points out in Subtle Is the Lord, his biography of Einstein, the effect of relativity was to turn Newtonian mechanics into an ‘approximate’ science, ‘not diminished but better defined in the process’.[*] It could be argued, indeed, that Einstein was the last Newtonian. Certainly Newton would have approved of Einstein's declaration that God does not play dice with the world.
The dice in question were the ghostly building blocks of quantum theory, that uncommonsensical account of subatomic reality devised by Max Planck at the turn of the 20th century. The theory replaced certainty with probability, a thing that Einstein could never bring himself to accept. One of the ironies of the Bergson-Einstein affair, as Canales notes, is that the world according to quantum theory – the world of quarks and black holes and microprocessors – seems decidedly closer to Bergson’s subtly intuitive version of it than it is to Einstein’s essentially mechanistic model.
The meeting in Paris that April evening was intended to bring physicists and philosophers together to consider the foundations and veracity of relativity theory. If I read Canales correctly, Bergson hadn’t intended to speak at all, and did so only when ‘prodded by an impertinent colleague’. All the same, he spoke for half an hour, setting out carefully his objections to, in fact his rejection of, Einstein’s conception of time as merely an aspect of the space-time continuum. For Einstein, our experience of time as a stately river that carries us along in its flow is an illusion; in relativity, there is no up and down, no right and left, no before and after. Creation is a kind of completed block, in which, as T.S. Eliot has it in the Four Quartets, ‘all time is eternally present,’ and time’s arrow can as easily shoot backwards as forwards. As Canales writes, using quotations from Hermann Weyl’s book Space-Time-Matter of 1922 – that year again – it was thanks to Einstein that
time had been finally ‘deposed from its high seat’, brought down from the lofty peak of philosophy to the practical down-to-earth territory of physics. [Einstein] had shown that ‘our belief in the objective meaning of simultaneity’ as well as that of absolute time had to be for ever ‘discarded’ after he had successfully ‘banished this dogma from our minds’.
Bergson, although he did not dispute the mathematical basis of relativity theory, profoundly disagreed with what he saw as Einstein’s mistaken, or at least inadequate, conception of the nature of time itself. Against it he set his own central hypotheses of Duration and Intuition, and the rather hazy notion of the Life-force, or Elan vital. Duration is his version of time, which proceeds not in a straight line, but wavers and quavers, biting into the future in a sort of endless process of creation. In his best-known book – in his day, that is – Creative Evolution (1907), he writes: ‘Though our reasoning on isolated systems may imply that their history, past, present and future, might be instantaneously unfurled like a fan, this history, in point of fact, unfolds itself gradually, as if it occupied a duration like our own.’ Such a pronouncement – translated, admittedly – is typical of Bergson’s gnomic style of thinking and expression. At first sight it seems to mean just what it says, but on closer examination the words and concepts exude a kind of gassy mist that obscures any insight the reader might have had a moment previously. Bergson’s doctrines of Intuition and Elan vital, as he presents them to us, are similarly shrouded, even though we seem to understand – intuit? – what they signify, at least while we are reading his account of them.
Bergson was seeking above all to assert the human dimension of experience, the validity of our intuitive sense that the world can be measured not only against scientific fact but also by way of our actions, thoughts, emotions. Einstein, more hard-headed, or at least wedded to a hard-headed interpretation of reality, preferred to put his trust in the empirical certainties, as he saw them, that science offered. His response to Bergson’s half-hour peroration took less than a minute. Its pivotal declaration was: ‘Il n’y a donc pas un temps des philosophes’ – ‘The time of the philosophers does not exist.’ What Einstein said next was even more controversial: ‘There remains only a psychological time that differs from the physicist’s.’ These two ways of regarding time, Canales remarks, would become
two dominant prisms inflecting most investigations into the nature of time during the 20th century … In the years that followed, Bergson was largely perceived to have lost the debate against the younger physicist. The scientist’s views on time came to dominate most learned discussions on the topic, keeping in abeyance not only Bergson’s but many other artistic and literary approaches, by relegating them to a position of secondary, auxiliary importance. For many, Bergson’s defeat represented a victory of ‘rationality’ against ‘intuition’. It marked a moment when intellectuals were no longer able to keep up with revolutions in science due to its increasing complexity … Most important, then began the period when the relevance of philosophy declined in the face of the rising influence of science.
The two opponents in the debate could hardly have been more unalike. ‘Einstein obsessively searched for unity in the universe,’ Canales writes, ‘believing that science could reveal its immutable laws and describe them in the simplest possible way. Bergson, in contrast, claimed that the ultimate mark of the universe was just the opposite: never-ending change.’ Bergson spent a few of his earliest years in England, but spent the rest of his life in Paris. His was what Canales describes as ‘an exemplary private life’, the life of a typical bourgeois academic, dividing his time between the lecture hall and the family home. His marriage was happy, and he cherished his only child, a daughter who was profoundly deaf but went on to be a successful artist. He was frugal, temperate and quiet. He was also a vegetarian; Einstein, by contrast, was a full-blooded carnivore: ‘Distinctly handsome,’ Canales writes, ‘he broke hearts as a teenager, had a daughter out of wedlock (who was most probably given away), was accused of adultery by his first wife, went through a prolonged legal battle over divorce and alimony [which he needed the Nobel money to pay for], and collected more than a few amorous peccadilloes along the way.’
He was also, behind the cuddly pose, fiercely ambitious and determined that he and his opinions should prevail, especially over a woolly-minded philosopher such as he considered Bergson to be. In this respect Canales traces a somewhat unsavoury seam in Einstein’s behaviour. During the debate, and in his follow-up book, Duration and Simultaneity, Bergson had written about the time dilation implications of relativity in such a way as to make it seem he simply did not understand Einstein’s new physics. Einstein postulated in the ‘twins paradox’ that if one of a pair of twins were to make a journey through space at a speed close to that of light – an impossibility then, and likely to remain so – he would return to earth younger than his brother, since time at such a speed slows down markedly. Bergson either did not accept this, or did not fully understand the proposition. In Duration and Simultaneity he wrote that his intention was to ‘explicitly prove that there is no difference, in what concerns Time, between a system in motion and a system in uniform translation’, and that if a clock were to be sent off travelling at close to the speed of light it would ‘not present a delay when it [found] the real [stationary] clock, upon its return’. ‘This single statement about clock delay,’ Canales writes, ‘has been enough to discredit him in the eyes of most scientists and some philosophers.’
The denigration of Bergson was quietly encouraged, so Canales claims, by Einstein himself. It is this aspect of the book that is likely to cause some controversy. Why, she asks, did commentators insist on judging the debate, and regarding Bergson as the loser in it, almost exclusively on the basis of the philosopher’s clumsiness in the matter of time dilation?
There are many reasons why and how people came to believe that Bergson made a mistake. Essential clues are hidden in archives – in Einstein’s correspondence for example. There we learn that it was Einstein himself who first and forcefully propagated this view, and that deep down (as we can read in his journal and later correspondence), he knew better.
Canales displays a scholarly scrupulousness in her attitudes to both men, but clearly she is determined that Bergson should have his due. The problem for him seems to have been that he was not as deeply concerned with the science per se of relativity theory, but with the implications of the theory in general for the lives of human beings. He did not consider that science, and physics in particular, was capable of striking to the heart of those truths on which we base our lives and by which we live them, or try to. ‘It is the essence of science to handle signs,’ he wrote in Creative Evolution, ‘which it substitutes for the objects themselves.’ He is not alone in holding this view. Here, for instance, is Karl Popper, in the significantly titled Quantum Theory and the Schism in Physics:
We owe to Kant the first great attempt to combine a realistic interpretation of natural science with the insight that our scientific theories are not simply the result of a description of nature – of ‘reading the book of nature’ without ‘prejudice’ – but that they are, rather, the products of the human mind: ‘Our intellect does not draw its laws from nature, but it imposes its laws upon nature.’ I have attempted to improve this excellent Kantian formulation as follows: ‘Our intellect does not draw its laws from nature, but it tries – with varying success – to impose upon nature laws which it freely invents.’
In this respect, Einstein himself on more than one occasion confessed his surprise that the physical realities of the world should conform so amenably to the laws of the man-made discipline of mathematics. Was he perhaps suspicious? Do we perceive reality, or manufacture it? Or to put it in Wittgensteinian terms, does science express only those things it is in its power to express?
In two fascinating sections in her book, on Einstein’s and Bergson’s contrasting attitudes to the new technology of the moving picture, Canales amply illuminates something of the essence of Bergson’s objections to Einstein's conception of time. The tiny instants of imagery that the film camera records and which are then run before us on the screen in what seems real time, are analogous to Einstein’s notion of time as a succession of segments progressing along a ‘world-line’ in four-dimensional space-time. For Bergson, time flows without a break. ‘The passing of time involved the creation of the new and the unforeseeable. Time was uncontainable. Every instant bit into the future.’ Canales goes on to quote the notes of an attendee at one of Bergson’s lectures:
The photographs that we take of a galloping horse are not, in reality, the elements of the gallop from which they were taken. And the cinematographic machine, that with these series of views, recomposes their trajectory, does not give us the illusion of movement other than by adding to these views, in the form of a certain mode of succession, the movement that in them they cannot contain.
In other words, there is movement, but ‘it is in the apparatus.’
The question of clocks and dilation in clock times was at the heart of the disagreement between the two men. Bergson eventually came to accept that a clock sent off into space at tremendously high speed would show a discrepancy with a clock stationary on earth: he just didn’t see that it mattered much. For him, modern science had detached itself from the world of ordinary human experience, which for him was the only version of the world that is, or should be, of interest to us. What is mere clock time compared to that rich inner sense we have of the ebb and flow of duration? As Canales writes, ‘Bergson was concerned with the questions of how, why and under what circumstances should the clock-delays described by relativity theory be unambiguously considered as real temporal changes.’ Bergson saw himself as engaged with the ‘question of allotting shares to the real and the conventional’. For Einstein, however, Bergson’s view of things was no more than a kind of happy dreaming: it lacked scientific rigour and refused to acknowledge the significance of measurable facts. Canales quotes the contemporary French philosopher Bruno Latour: ‘We recognise here the classical way for scientists to deal with philosophy, politics, and art: “What you say might be nice and interesting but it has no cosmological relevance because it only deals with the subjective elements, the lived world, not the real world.”’
The Physicist and the Philosopher is an extraordinarily rich and wide-ranging work. Canales has rescued from near oblivion a fascinating, highly significant debate that is still relevant in an age which has begun uneasily to question the hegemony of science and its uncontrollable child, technology. The slipshod editing of the book does ill service to Canales’s style and scholarship. She gives an account of the debate and its many ramifications that is admirable for its clarity – the book is aimed at the common reader, and, I should add, at the common reviewer – and strives at all times to be fair to both figures in the debate. At the close of the book she admits that the divisions between science and philosophy are still as wide as they were at the time of the debate, if not wider, but chooses to take her stance in the ‘in-between territory of dualistic dichotomies,’ where ‘we can consider our universe filled with clocks, equations and science as much as with dreams, memories and laughter.’