Published in 1915, Einstein's general theory of relativity offered a radically new account of gravitation which was as mathematically forbidding as it was conceptually novel. Several of the finest mathematical astronomers in Europe were soon captivated by the theory's cosmological possibilities, yet it made just three new, testable propositions: it correctly accounted for the well-known anomaly in the orbit of the planet Mercury without resort to unobserved planets or clouds of interplanetary dust; it predicted that a beam of light passing close to a massive gravitating body such as the Sun would be minutely deflected (the ‘light-bending’ effect); and it predicted that spectral lines from the Sun would be shifted slightly towards the red end of the electromagnetic spectrum when compared with the same lines from terrestrial sources (the ‘red-shift’ effect). As relativity emerged as a serious challenger to the long-accepted Newtonian theory of gravitation, the credibility of Einstein's work came to rest heavily on the verification of the latter two predictions.

Most historians of science know that a key turning point in this story was the alleged verification of the second of the above predictions by a British eclipse expedition led by A. S. Eddington in 1919. When the result was announced at a joint meeting of the Royal Society and the Royal Astronomical Society in November of that year it was portrayed as a verification of general relativity, thereby sparking unprecedented international press coverage of Einstein's triumph and Newton's apparent demise. A theory previously known only to a handful of European experts was now a major topic of international discussion. But, as most historians of science also know, Eddington's results were questionable. Not only were they based on extremely difficult measurements and the judicious selection of data, but by 1919 Eddington had become the chief British spokesman for relativity with a vested interest in seeing the theory verified.

Jeffrey Crelinsten's book places the astronomical verification of the general theory in a new and very different context by tracing its reception by American astronomers. His central argument is that these men took a quite different view of the theory to that adopted by most of their European peers. Theoretically inclined astronomers in Europe were attracted to Einstein's work because of its radically new approach to space, time and gravitation, and because it opened the possibility of a new science of cosmology. Figures such as Eddington and the Dutch astronomer Willem de Sitter were so entranced by the theory's mathematical beauty and revolutionary consequences that they felt its empirical verification to be something of a formality.

The Americans saw things differently. Untrained in the mathematics necessary to master Einstein's work, they were highly suspicious of an apparently incomprehensible theory which threatened their established expertise in Newtonian celestial mechanics. Yet, convinced by leading European astronomers that relativity was important, they sought to contribute to the international debate by testing its astronomical predictions. Crelinsten reminds us that in the early years of the twentieth century, astronomy was a larger scientific enterprise than physics, and one of the few in which the Americans had technical resources comparable to those of their European peers. Thanks to American expertise in precision engineering, the willingness of philanthropists to fund huge telescopes, and the excellent seeing conditions in the mountain observatories of California, American astronomers embraced the new sciences of stellar spectroscopy and eclipse photography as areas in which they could become world leaders. These were, moreover, exactly the areas of expertise necessary to test the red-shift and light-bending predictions respectively.

One important theme of Crelinsten's book, though one to which he devotes little explicit discussion, is the gradual emergence of American astrophysics as a force to be reckoned with at international level. Thus in the spring of 1919 H. D. Curtis and W. W. Campbell from the Lick Observatory in California were convinced that their eclipse observations of 1918 had proved that Einstein's light-bending prediction was wrong. Campbell went to London to announce these results but, learning from British astronomers that Eddington would almost certainly use the results of his 1919 expedition to support Einstein, he began to question the Lick results, eventually suppressing their publication entirely. The British Astronomer Royal later sent American astronomers copies of the British eclipse photographs so that they could ‘see what our star images look like’ (p. 147). These events suggest that European astronomers retained authority, even in observational astronomy, in the first two decades of the twentieth century, and that forming a common, transatlantic astrophysical community was a difficult business.

By 1922 the situation had changed. Of several expeditions sent to photograph the eclipse visible in Australia that year it was the one from Lick Observatory which was regarded as the most reliable. In April 1923 Campbell was ready to announce that Einstein's light-bending prediction had been confirmed so precisely that his observatory did not intend to repeat the experiment at subsequent eclipses. The confidence and authority of the American observatories was clearly growing.

American astronomers also played a major role in testing the red-shift prediction. These measurements were especially difficult because they required teasing apart the effects of several little-understood solar phenomena believed likely to contribute to spectral changes. Crelinsten's study is important in describing how this problem was tackled independently, though competitively, by two of the world's leading solar spectroscopists, C. E. St John at Mount Wilson Observatory in California and the British astronomer John Evershed working at the Kodaikanal Observatory in India. In 1923 Evershed became the first to claim that solar spectra supported Einstein's prediction, thanks in part to his connection with British theoreticians who were able to suggest the kind of measurements most likely to be reliable. Shortly afterwards, St John's long-standing and detailed investigation of solar spectra drew him to a similar conclusion. The conversion of the American sceptic to Einstein's cause had important consequences. On the one hand his support carried enormous weight because he had long resisted interpreting his data in a way favourable to Einstein, on the other Evershed felt his own painstaking work to have been seriously undervalued because he had – rightly, as it turned out – taken a more positive approach to Einstein's work.

Crelinsten uses the pro-Einstein announcements by Campbell and St John in 1923 to highlight further differences between European and American attitudes to relativity. Where many European scientists welcomed experimental confirmation of a theory already under active development, most Americans, while accepting the experimental data, hardened their resistance to theoretical claims they found incomprehensible. Many held out hope that Newton's theory would eventually be brought into line with the new data, while a minority launched vicious attacks on Einstein himself, accusing him of plagiarism and attempting to defame him through anti-German, anti-Semitic and anti-Bolshevik slurs. Crelinsten uses the increasingly fractious relations between sceptical American astronomers and those Americans actively hostile to relativity to examine tensions in the American scientific community, especially between theoreticians on the East Coast and observers on the West.

The story reaches its climax around 1928. By this time American astronomers had not only confirmed the positive observations made earlier in the decade but, using stellar theory developed by Eddington, found new ways of verifying the red-shift prediction using spectral evidence from distant stars. The latter measurements were only possible using the hundred-inch telescope at Mount Wilson Observatory, thereby confirming a new dependency between European theory and American observational astronomy. The American astronomers who had once merely tested relativity now became its advocates. Crelinsten concludes that this was partly because they had to counter the increasingly unpleasant and unfounded attacks of relativity's American detractors, but mainly ‘because it had passed crucial tests’ (p. 300; original emphasis). As Crelinsten himself implies, however, the story is somewhat more complicated. By the end of the 1920s American astronomers found themselves in the forefront of the observational development of an exciting new relativistic cosmology. They were still not required to accept the theory whose predictions they had done so much to verify, but it would have been odd for them not to have done so given their increasing interaction with European theoreticians who took the theory for granted. How a truly American community of relativistic cosmologists was eventually established is a story which remains to be told.

It is fair to say that Crelinsten adopts a more descriptive than analytical historical approach throughout his book. His story unfolds chronologically and in considerable detail, guided by the author's impressive command of the primary source material. There nevertheless seemed to this reviewer to be some tension between the book's apparent aspirations to be both a semi-popular and a scholarly history. Crelinsten keeps technical discussion to a minimum while embedding his own historical contributions in a much broader narrative covering the interaction between relativity and astronomy from 1905 to 1930. This approach will appeal to historians and scientists who are non-specialists in the field but the narrative is surely still too dense and detailed to make any impact on the ‘general culture’ discussed in the book's final paragraphs.

The broad narrative also means that those with a professional interest in the field have to a large extent to decide for themselves where Crelinsten's own original contributions to the story of the reception of general relativity lie. Crelinsten chooses not to engage in historical or historiographical debate with earlier work in the field, sometimes ignoring literature that is clearly relevant. The most striking example is Klaus Hentschel's groundbreaking and well-known work on St John's contribution to verifying the red-shift prediction (in Science in Context (1993), 6, 137–94). Crelinsten's comparative study of St John and Evershed is plainly at odds with some of the claims made by Hentschel but, although the latter's work is included in the bibliography, it is not mentioned or cited at all in the sections on the red shift. Likewise Crelinsten's account of why astronomers took a different view of relativity from physicists, of how the theory was mastered and propagated by de Sitter and Eddington, and of the role played by Eddington in founding the first research groups in relativistic cosmology, entirely ignores the present reviewer's work on exactly the same topics (Masters of Theory, Chicago, 2003, Chapter 9).

The few contentious issues Crelinsten does address directly are relegated to extended footnotes. There he challenges important aspects of Earman and Glymour's classic paper on the attempts to measure the light-bending prediction (Historical Studies in Physical Sciences (1980), 11, 49–85), and Jean Eisenstaedt's claim that general relativity was little studied in the period from 1925 to 1955 because it was too technically demanding and of little relevance to the exciting new field of quantum mechanics. Crelinsten perhaps wished to avoid contentious issues in a semi-popular book but his study would surely have had a much larger impact on the scholarly community had he highlighted these important points of difference and developed their interesting implications more fully. It is also disappointing to this reviewer that Crelinsten makes little attempt to engage the growing literature on the rise of astronomy, the sciences and mathematics in the United States from the late nineteenth century. The obvious comparison would be with physics, especially given common actors such as Albert Michelson and common institutions such as Caltech.

These issues aside, however, Crelinsten is to be congratulated on having made a substantial contribution to our understanding of the reception of general relativity by American astronomers, and the central role they played in placing the theory's astronomical predictions beyond doubt. Earman and Glymour's study of the British eclipse expedition of 1919 has long served in history of modern physics courses as a classic study in the interplay between technical, social and political issues in theory-testing. Einstein's Jury moves the debate forward. Where Eddington exploited the poor quality of his data to gamble on a theory he hoped was right, American astronomers built their international reputation by confirming Einstein's predictions well within the limits of experimental error. Crelinsten's story emphasizes that Einstein's move from the special to the general theory of relativity was also a disciplinary shift from physics to astronomy and cosmology. While physicists took little interest in a difficult theory irrelevant to their everyday work, astronomers made new worlds inside their new observatories.