How experiments are remembered: The discovery of nuclear fission, 1938--1968.

摘要

The discovery of nuclear fission in 1938-1939 involved four individuals separated by geography, politics, and scientific discipline. Otto Hahn and Fritz Strassmann were chemists in Berlin who in December of 1938 discovered barium in a sample of irradiated uranium. Lise Meitner and Otto Robert Frisch were physicists who had each emigrated first from Vienna to Berlin, and then, facing increasing persecution from the Nazi regime due to their Jewish heritage, from Berlin to Stockholm and Copenhagen, respectively. The two (who were also aunt and nephew) spent Christmas of 1938 together in the Swedish countryside, where they pondered the Hahn and Strassmann's (also Meitner's former colleagues) finding. Meitner and Frisch soon explained Hahn and Strassmann's data by proposing a new form of nuclear decay, in which a heavy nucleus splits approximately in two, which they termed "nuclear fission." Frisch also verified the existence of this decay through physical methods, different from the chemical methods of Hahn and Strassmann.;In this work I examine the discovery of nuclear fission from two primary perspectives, the first historical and the second historiographical. Through both parts, I follow the two scientists who were arguably the most responsible for the fission discovery, and who have been the most celebrated as its discoverers: Lise Meitner and Otto Hahn. In telling the fission story through the lenses provided by Hahn and Meitner---their diaries, correspondence, and the stories told about them by others---I seek most fundamentally to divorce the history of fission from that of the atomic bomb. As I argue in the work that follows, once the atomic bomb gained the cultural resonance it still possesses today, it changed the way in which we understand our history. The history of the scientific study of the atom and atomic nucleus before 1945 was no longer seen in its own light, as developments that contributed to the construction of a certain paradigm of the natural world, but as developments that led to the construction of the atomic bomb. In studying fission through the eyes of Meitner and Hahn, neither of whom worked on the Manhattan project, I gain new insight into this history.;In sum, I offer two arguments. One, in terms of history itself, I argue that historians of science should understand the discovery of fission in terms of the early twentieth century culture of the science of radioactivity, not in terms of the post-1945 culture of nuclear physics. Two, on a historiographical level, I argue that the way in which the discovery of nuclear fission has often previously been understood is the result of the post-1945 intersection of the world of physics and the spheres of politics and the public, and in particular the conflation of the roles of public scientist and eminent physicist.;In the first part of this work (chapters one and two) I offer a careful study, based on drafts of scientific journal articles and personal correspondence preserved at the Max Planck Society Archives in Berlin and the Churchill Archives Center in Cambridge, England, of the process by which Otto Hahn, Lise Meitner and Fritz Strassmann came to conclude that in irradiating uranium with neutrons, rather than producing elements heavier than uranium, they were causing the uranium nuclei to split---or "fission"---into two lighter nuclei. Contrary to previous work which has seen the moment in December 1938 when Hahn and Strassmann found evidence of barium in their irradiated uranium as the moment when fission was discovered, I argue that the discovery of fission was a process, and that Meitner, Hahn and Strassmann did not completely dismiss their previous conclusions until months after the December finding. Viewing the fission discovery as a process also serves to offer an alternative to previous histories that have depicted the discovery of fission as simply a step on the path toward the atomic bomb. Contrary to this, I explore the multiple theoretical and experimental applications for fission foreseen by scientists in 1939, before most of them had even conceived of the possibility of an atomic bomb.;The atomic bomb, however, does loom large in the second part of this work (chapters three, four and five), in which I examine the different ways in which the fission story was told in the thirty years between the discovery and Otto Hahn and Lise Meitner's deaths in 1968. In chapter three I focus on the role of scientific disciplines in these narratives, and in particular the way in which Otto Hahn attempted to establish both his identity as a chemist, and chemistry's role in the discovery of fission in the narratives he created. Ultimately, however, Hahn was willing to leave the rhetoric of chemistry behind in return for personal fame as fission's discoverer. In chapter four I turn to Lise Meitner who, because she had had to flee Berlin before the fission discovery, was in the American press of 1945 widely and prominently celebrated as the discoverer of fission, and as the Jewish woman who kept the secret of the bomb safe from Hitler. Some previous historians have overlooked this brief period during which Meitner received the vast majority of credit for the discovery, and instead assumed that because she was a woman her role in the discovery was always minimized. Soon after receiving credit for the discovery, however, Meitner lost this credit, and it is the primary reason for this to which I turn in chapter five. I argue that in the post-World War II world, largely as a result of their new status as creators of the atomic bomb, eminent scientists were expected to play a political role in the public sphere, to become "public scientists." Because Meitner was unwilling to play this role, while Hahn was willing to do so, the fame that had been Meitner's was swiftly transferred to Hahn. As a result, Meitner was soon forgotten and Hahn became the discoverer of fission, which he remained through 1968, and to great extent through the present day.