Who is a real, genuine scientist? For reasons that have been studied in depth, Albert Einstein became and still partly remains the icon of science itself. Opposing Einstein is, to a large extent, the same as opposing science, and rejecting the theory of relativity has become synonymous with obsolescence. Nevertheless, the time for Einstein-centred accounts in which the failure to understand and accept the revolutionary truths of relativity has to be blamed on the contestants' stubbornness, arrogance or simply ineptitude is largely gone. Philosophical reasons, mathematical interpretations, pedagogical traditions, political and ideological settings and so on coalesce in giving a complex picture of the many ways relativity was early on understood, accepted or rejected.

First published in German in 2009, Einstein's Opponents is the outcome of a doctoral dissertation in which Milena Wazeck succeeds in applying new brush strokes to the canvas depicting the hostility to Einstein and the theory of relativity. At the core of her thesis we find the debate over what counted as authentic science, as professional or academic work and illegitimate charlatanry or amateurism. Her main characters are people who saw themselves as ‘real’ scientists – as opposed to ‘academic’ physicists – whose mission in the world was to rescue knowledge from the bigotry of academia. Members of the latter were, according to the former, narrow-minded, excessively mathematical and esoteric, blind to the big questions, and constitutive of an exclusivist group. The proponents of ‘real’ science were a heterogeneous mix of engineers and professional scientists (physicians, chemists, experimental physicists) together with schoolteachers, philosophers, journalists and many other self-appointed men of science. The term Wazeck coins to encompass them is the German construction Welträtsellöser, which becomes the less appealing ‘world riddle solver’ in the English translation.

The book unveils the loose network of people united by the common goal of opposing relativity. At the centre of this network were two key people: Ernst Gehrcke, an established physicist working mostly in optics at the Reich Institute of Physics and Technology in Berlin, and Arvid Reuterdahl, a Swedish-born engineer with academic and civil positions in America. The archival material from them both, so far hardly delved into by historians, is sufficient for this network to be reconstructed. But this web was often neither explicit nor easily held together. Many of the people the book talks about hardly knew each other, and they only had in common the fact of exchanging letters with one of the two central characters. Furthermore, opposition to Einstein's relativity proved to be an insufficient motive to hold people together, due to the diversity of reasons for their hostility.

This diversity is the core of the long third chapter. From metaphysical conceptions of time, space or light to prejudices in favour of or against the ether; from occult conceptions of gravitation to complaints against mathematical physics – those who opposed Einstein often did so because they saw their own global theories threatened by one aspect of relativity. For instance, advocates of some variant of philosophical vitalism could not agree to the relativity of time, since the intricate relationship between life and time meant that both had to be either absolute or relative, and the second option was, from their point of view, tantamount to materialism. Rejection of Einstein's relativity in full was normally based on the denial either of a basic principle or, more often than not, of one specific consequence of the theory. It also happened that the theory was dismissed on the basis of priority claims over some such consequences, as in the case of those Welträtsellösern whose all-embracing theories had already done away with the ether before Einstein and, on their own view, with better foundations.

Chapter 4 discusses the efforts and techniques used to create a community of Einstein's opponents. In one way or another, they all shared the sense that a conspiracy was at the origin of the success of relativity: on the part of the editors of journals, of university leaders, or of a supposed Jewish lobby. Similarly, the strategy of people like Gehrcke and Reuterdahl was to attempt to exploit their publication niches, not so much in specialized journals but rather in the popular press. They also formed associations like the well-known Association of German Natural Scientists for the Preservation of Pure Science, the lesser-known and short-lived Academy of Nations, and the German Society for Universal Ether Research and Comprehensible Physics.

The geographical scope of the book is mainly Germany and Central Europe, with some episodes in the United States, especially due to Reuterdahl. The reader is left wanting treatment of the relationship with anti-relativity movements in France and, most especially, in Britain. The internal analysis of these anti-Einstein networks is the great contribution of this research, while the actual influence of these groups among professional scientists and in public opinion is left largely unscrutinized. Although the book is largely Einstein-centred, the core of the argument is to prove that opponents to relativity had no particular hatred of Einstein, but rather objected to the academic and popular success of a theory that they regarded as only the main example of a trend they thought of as anti-scientific. Thus the book is more about what Wazeck calls Welträtsellösern than about Einstein himself, or even relativity.