S PECIAL F EATURE: W AR AND P EACE www.iop.org/journals/physed The Manhattan project—a part of physics history Ann-Marie Martensson-Pendrill˚ Department of Physics, University of Gothenburg, SE-412 96 G¨oteborg, Sweden E-mail: [email protected] Abstract Current physics textbooks tend to exclude military applications, but it is explained here how a study of the Manhattan project—the devastatingly successful attempt to develop an atomic bomb—can show students how the lives and work of physicists are shaped by events in society. Much of the original source material is available in books and on the internet (and referenced here), which allows students to discover the views of the scientists for themselves. In the early morning hours of July 16 important for shooting cannons and guns and drop- 1945, a truck driver in New Mexico ping bombs. In older textbooks, these examples reported that he saw the sun about to rise often dominate, whereas more modern texts are at 4 am. The sun decided it was too early, likely to include or even focus on more everyday he said, so it went down again and came applications such as throwing balls or jumping. up an hour later [1]. There is also a trend to include more historical as- Robert Oppenheimer quoted the Bhagavad- pects which can give an opportunity to focus on the Gita: ‘I have become death, the shatterer of development of ideas in physics. Still, many newer worlds.’ The picture of the mushroom cloud textbooks mention the bomb very briefly, if at all. carries a strong symbolic load. It demonstrates How could a discussion of the Manhattan project vividly that the fruit of knowledge can contribute contribute to the image of physics or physicists? not only to the benefit of mankind but also bring The Manhattan project represented a water- immense destructive power and be a root of evil. shed in the relationship between physics, physi- Over the post-war decades, the public image of cists and politics [3]. science and scientists has changed from hero to After the war, physicists were often asked a common stereotype view of a ‘mad scientist’, often evil and selfish [2]. The turning away to go to Washington and give advice from science studies, which is a concern in many to various sections of the government, countries, may be not only because of lack of especially the military. What happened, knowledge or understanding of science, but rather I suppose, is that since the scientists from encountering its dark side. Physics can no had made these bombs that were so longer claim innocence. ‘I have become death, the important, the military felt we were shatterer of worlds.’ useful for something. Feynman [4, p 53]. The Manhattan project can show us physicists Physics teaching choices at work, and how their lives and research are Should physics teaching include military applica- shaped by the events in society (and sometimes tions? The understanding of projectile motion is shape them). Since many physicists have 0031-9120/06/060493+09$30.00 © 2006 IOP Publishing Ltd P HYSICS E DUCATION 41 (6) 493 A-M Martensson-Pendrill˚ after the Manhattan project. Towards the end of Timeline the course we then made a very informal roleplay, where I provided a timeline as a plan for the lesson, 1938 Fission of uranium discovered (Hahn, Meitner, Strassmann, Frisch) and the students took turns in the involvement of 1939 2 August, Letter to President ‘their’ physicist. Some chose a detached approach, Roosevelt (Einstein, initiated by Szilard) but many did their presentations in the first person; 1941 Heisenberg visits Bohr in Copenhagen some even dressed up. The informal character of 1942 23 September, Oppenheimer the class made it natural to stop for discussions appointed scientific director of the at any time. The audience was only ourselves. Manhattan project at Los Alamos Discussions of the responsibilities of scientists 1942 2 December, The first controlled become more interesting and thought-provoking nuclear reaction, Enrico Fermi, against a backdrop of historical events and the University of Chicago reactor reflections from those involved. The roleplay 1945 3 July, Szilard petition opened up ethical discussions through the voice 1945 16 July, Trinity test—world’s first of another person, which is often easier. Many of atomic blast the students also remarked on the deep impression 1945 6 and 9 August, Hiroshima and Nagasaki made by the discovery of how much the physicists 1949 Start of ‘Oppenheimer affair’ had already achieved at a young age. 1952 First hydrogen bomb explosion Socio-scientific issues, such as this one, are 1953 Oppenheimer faces a security hearing multidisciplinary in their character. In a school that ultimately recommended that situation, a possibility would thus be to do his security clearance be ended such a project together with, for example, the history and/or English teacher. A more ambitious More detailed timelines can be found, e.g. at approach could involve a drama teacher and aim NuclearFiles.org (www.nuclearfiles.org/menu/ for a performance for another class or at a school timeline/html index.htm) and at the WWW open-house day. In this issue Kofoed describes pages from the National Atomic Museum in how the decision to drop the bomb has been New Mexico (www.atomicmuseum.com/tour/ used in a roleplay in secondary-school classroom atomicage.cfm). situations [5]. One might argue that the Manhattan project described the period in their autobiographies, it is not really part of physics, but could and should gives us an opportunity to meet the physicists as be left for the history teacher, if included at persons, dealing with difficult ethical problems. In all. However, this approach could easily add to addition, many original documents, for example the image of scientists as lacking conscience and from various hearings, have been released and concern for society and maintain or widen the gap are often easily accessible on the WWW. We between ‘the two cultures’. From a physicist’s have the possibility to read their words, and point of view, the roles, thoughts and actions of sometimes even to listen to their voices from the our older colleagues are of particular interest. past. I have used these sources to help physics I present below a brief summary of what teacher students develop a richer understanding may be included and references to useful sources. of the context of atomic and nuclear physics and Wherever possible, I have provided WWW links, physicists and their relation to society. I have also because I have found that this considerably used a similar approach within interdisciplinary facilitates the administration of the task. I have courses for future teachers. To initiate the project, made a personal choice of quotes from much I provided a list of names of physicists with longer texts. I have tried to find examples of significant roles in the development, together with physicists struggling with the questions of the web addresses, and some journal articles and role of physics and physicists. Are the quotes books. representative? Find out! An important aspect The students (in a group of 15–20) were asked of this project is to develop an awareness that to sign up for one of the physicists, and read up one need not depend only on textbook or other on their involvement before, during and sometimes presentations, but that it is possible to go back 494 P HYSICS E DUCATION November 2006 The Manhattan project—a part of physics history to original sources and form more independent theory and design and acted as a scientific father opinions. I strongly encourage you to make confessor to the younger men.... His real function use of the richness in internet access and read there was that he made the enterprise which looked the original documents for yourself and let your so macabre seem hopeful’ [11]. students have a chance to read the previously top Many physicists’ flights include adventures. secret documents and hear some of the voices from When Bohr flew from Stockholm to London in the history of physics. the bomb bay of the plane, he fainted from lack of oxygen. Enrico Fermi, whose wife was Jewish, Ideas, politics and adventures never returned to Italy after the Nobel prize award ceremony, but continued directly on to New York. The photographs [6] from the early Solvay conferences show the key physicists of the 1920s getting together for discussions about the Los Alamos fundamentals of quantum physics, laying the Because of the danger that Hitler might ground for our understanding of atoms and nuclei. be the first to have the bomb, I signed This period is delightfully described in Gamow’s a letter to the President which had ‘Thirty Years That Shook Physics’[7], which gives been drafted by Szilard. Had I known a human side to the results presented in textbooks. that the fear was not justified, I would The Nobel museum (www.nobelprize.org)also not have participated in opening this has extensive information on the life and work of Pandora’s box, nor would Szilard. For many of the physicists involved. my distrust of governments was not The developments in Europe during the 1930s limited to Germany. Einstein [12]. changed the lives of many people, including scientists. Both before and during the war, The Manhattan project brought together a many physicists were forced to move abroad. remarkable collection of the leading physicists When fission of uranium was discovered in 1938, of the time. Many of the names we recognize in experiments prepared by Hahn, Meitner and from groundbreaking works presented in physics Strassmann, Lise Meitner was already exiled in textbooks.