In 1919, two small teams of physicists and astronomers set out on two expeditions. One team travelled to Principe in Africa, the other to Sobral in Brazil, but both had the same mission in mind – to take photographs of the sky during an eclipse. That November, some months after their return, the results of these expeditions were announced at a joint meeting between the Royal Society and the Royal Astronomical Society. The following day, The Times reported this meeting under the dramatic headline, ‘Revolution in Science’. While The Times was not averse to science reporting back then, such a headline was hardly the norm. Furthermore, a number of less ‘science-friendly’ publications also chimed in. The socialist Daily Herald gleefully proclaimed a ‘Bloodless Revolution’, the Daily Express noted that something was ‘Upsetting the Universe’, and the Daily Mail contributed with a cheeky ‘Light Caught Bending’.
As is probably clear by now, there was something more interesting going on than a mere eclipse. The scientists’ plan had been to test Einstein’s general theory of relativity, and it would seem they had been successful. Indeed, the expedition has recently been nominated in the Great British Innovation Vote, a venture to find the most important British innovation in science and technology from the past 100 years. With celebrity endorsements a staple of the Great British genre, the science writer Simon Singh has put his backing behind the eclipse expedition, explaining why he chose a test rather than a theory. He argues that theories are only really taken seriously once they’ve been tested, and that after relativity theory had been tested: ‘Newton’s theory of gravity was dead or at least it was wounded on the cosmic scale and Einstein’s theory became king.’
If you believe the newspaper reports of 1919, then this is certainly true. At the same time as proclaiming revolution, The Times also declared ‘Newtonian Ideas Overthrown’, and the next day followed this up with ‘Newton vs. Einstein’. It would seem that the eclipse expedition had been an overwhelming success and Einstein’s theory of relativity had overthrown the Newtonian foundations of physics. But, of course, neither history nor science are ever that straightforward, and the expedition and its results were by no means perfect. If, however, there’s ever a vote for a Great British Science Publicity Campaign, then the expedition would probably do quite well. It may not have single-handedly confirmed relativity theory, but it was framed and reported as if it had, and the results of this are still being seen today.
The making of a revolution in science
The expedition was organised in part by Arthur Stanley Eddington – physicist, Quaker, and (I like to think) general nice guy. He was also Plumian Professor of Astronomy at Cambridge, Secretary of the Royal Astronomical Society, and one of the first British converts to relativity theory. Einstein had already put forward three consequences of relativity theory that could be proved experimentally. The first, the orbit of Mercury when it’s closest to the sun, had long been a problem for Newtonian mechanics and was resolved with relativity theory. The third, involving gravitational redshift, was a bit trickier and would have to wait until 1959 to be measured in a laboratory setting. The second prediction, however, was ripe for observational confirmation. According to Einstein’s theory, starlight should be deflected by the sun’s gravitational field. So when the sun is near the stars, their position should appear to be slightly different from when the sun is further away. (Newtonian mechanics did also predict a deflection, but it was roughly half the amount of Einstein’s deflection.) Unfortunately, with the sun being notoriously bright, you can’t see starlight when it’s nearby – but there is a way around this. Eddington planned to observe the stars during an eclipse. The only problem now was to find a suitable eclipse, and wait for the First World War to be over.
In 1918, the war ended, a Joint Permanent Eclipse Committee (JPEC) was established with Eddington and the Astronomer Royal (Frank Dyson) at its helm, and the eclipse of May 1919, visible in Principe and Sobral, was chosen. Almost immediately, the publicity machine was underway. As early as January 1919, the plans for the expedition were being reported in The Times, and this coverage would continue in the following months, all the way up to the November ‘revolution’ article. The articles were either written by members of the JPEC themselves, or based on information provided by them. (One such member, the astronomer Henry Park Hollis, was hired as The Times’ astronomical correspondent that same year.) Meanwhile Eddington, whose gifts at public exposition would be confirmed by a best-selling book in roughly a decade’s time, was busy promoting the eclipse to any audience that would listen.
The JPEC were able to ensure not only that the eclipse was covered in the first place, but also the nature of this coverage. They framed the expedition as a crucial experiment by setting up a trichotomy of results. Members of the JPEC discussed the expedition in terms of three possible results: zero deflection, the Newtonian-half deflection and Einstein’s deflection. Of course, this ignores all the other amounts in between and alternative explanations. And it meant that if the deflection measured was a bit more than Newton’s and a bit less than Einstein’s, then Einstein would still be victorious.
In the end, the results obtained weren’t exactly definitive. The Principe skies were cloudy, a lot of the photographs didn’t come out very clear, and the deflection appeared to be somewhere in the middle of the two values. But because the press, the public and other scientists had been primed to expect a crucial experiment, they were happy to accept this as a crucial result. And Eddington’s credibility helped matters considerably. When he announced his results at the November meeting, most people in the audience were pretty sure they’d just witnessed a definitive confirmation of relativity theory. One such audience member was Peter Chalmers Mitchell, a prestigious biologist who was also forging a second career for himself as The Times’ scientific correspondent. He wrote a relatively measured report of the meeting, an enthusiastic sub-editor (presumably) tacked on the dramatic ‘Revolution in Science’ headline, and a media storm was born. While the ‘Revolution in Science’ article did a lot of the work here, it was the earlier articles, carefully fed to The Times by the JPEC, which laid down the foundations. Here we have a master class in public relations, a lesson in how to be both effective and invisible (until a pesky historian unravelled the whole thing 80 years later).
Epilogue: Damage control
But the JPEC publicity campaign can also serve as a warning of the unintended consequences of press attention. Because framing the whole thing as a ‘revolution’ didn’t really fit in with the notion of scientific progress that Eddington and many of his peers were trying to promote. The potential dangers of a rhetoric of revolution were evident even before The Times’ famed headline. In May 1919, an article in the Manchester Guardian noted:
‘It is a useful reminder in this age of enlightenment that however tall and wonderful be the structures that science builds she is all but childishly ignorant still of the bases on which they are reared’
‘The Eclipse of the Sun’, The Manchester Guardian, 26 May 1919, p.6
Physicists had spent a couple of hundred years defining their discipline as the ‘king’ of the sciences, the ultimate route to knowledge. Newton’s fundamental laws of mechanics were central to this, providing the foundations of all natural actions and phenomena. If it now turned out that Newton had been wrong all along, then why should anybody believe a physicist ever again? This was a problem for Eddington – he was eager to promote Einstein’s theory as an exciting new development in physics, but he hadn’t been planning on denouncing Newton. The Times headline maybe went slightly too far. And the situation wasn’t helped by other physicists also shouting ‘revolution’: Oliver Lodge, a vocal sceptic of relativity theory, went so far as to publicly compare relativists to Bolsheviks.
Eddington responded to ‘revolution’ with some damage control. In late November he wrote that it was ‘not necessary to picture scientists as prostrated by the new revelations, feeling that they have got to go back to the beginning and start again. The general course of experimental physics will not be deflected, and only here and there will theory be touched.’ Another JPEC member, the astronomer Andrew Crommelin, responded in a similar fashion, insisting that ‘some newspapers went too far in speaking of the Einstein theory as overthrowing the Newtonian theory’. He pointed out that the practice of astronomers wouldn’t be affected and ‘it would not be necessary to make new planetary tables at all’.
It was a fine line to tread, and it continued to be trod for the next two decades as physicists dealt with the implications of their modern theories. But it seems to have been a success. Today, Newtonian and Einsteinian concepts of the universe happily coexist. The foundations of physics have not been shattered. Eddington got his crucial experiment and exactly the conservative revolution he wanted.
Alistair Sponsel (2002): ‘Constructing a ‘revolution in science’: the campaign to promote a favourable reception for the 1919 solar eclipse experiments’, British Journal for the History of Science 35(4): 439-467
J. Earman and C. Glymour (1980): ‘Relativity and Eclipses: The British Eclipse Expeditions of 1919 and their Predecessors’, Historical Studies in the Physical Sciences 11(1): 49-85
Matthew Stanley (2003): ‘An Expedition to Heal the Wounds of War”: The 1919 Eclipse and Eddington as Quaker Adventurer’, Isis 94(1): 57-89