The Manhattan project - a part of physics history

Ann-Marie Mårtensson-Pendrill
Physics Education 41 (2006) 493-501

In the early morning hours of July 16 1945, a truck driver in New Mexico reported that he saw the sun about to rise at 4.a.m. The sun decided it was too early, he said, so it went down again and came up an hour later. [1]
Robert Oppenheimer quoted the Bhagavad-Gita: "I have become death, the shatterer of worlds". The picture of the mushroom cloud carries a strong symbolic load. It demonstrates vividly that the fruit of knowledge can contribute not only to the benefit of mankind but also bring immense destructive power and be a root of evil. Over the post-war decades, the public image of science and scientists has changed from hero to a common stereotype view of a "mad scientist", often evil and selfish [2]. The turning away from science studies, which is a concern in many countries may be not only because of lack of knowledge or understanding of science, but rather from encountering its dark side. Physics can no longer claim innocence. "I have become death, the shatterer of worlds."

Physics teaching choices

Should physics teaching include military applications? The understanding of projectile motion is important for shooting cannons and guns and dropping bombs. In older textbooks, these examples often dominate, whereas more modern texts are likely to include or even focus on more everyday applications such as throwing balls or jumping. There is also a trend to include more historical aspects which can give an opportunity to focus on the development of ideas in physics. Still, many newer textbooks mention the bomb very briefly, if at all. How could a discussion of the Manhattan project contribute to the image of physics or physicists?

The Manhattan Project represented a watershed in the relationship between physics, physicists and politics. [3]

After the war, physicists were often asked to go to Washington and give advice to various sections of the government, especially the military. What happened, I suppose, is that since the scientists had made these bombs that were so important, the military felt we were useful for something. Richard Feynman [4, p53].

The Manhattan project can show us physicists at work, and how their lives and research are shaped by the events in society (and sometimes shape them) . Since many physicists have described the period in their autobiographies, it gives us an opportunity to meet the physicists as persons, dealing with difficult ethical problems. In addition, many original documents, e.g. from various hearings, have been released and are often easily accessible on the WWW. We have the possibility to read their words, sometimes even listen to their voices from the past. I have used these sources to help physics teacher students develop a richer understanding of the context of atomic and nuclear physics and physicists and their relation to society. I have also used a similar approach within interdisciplinary courses for future teachers. To initiate the project, I provided a list of names of physicists with significant roles in the development, together with web addresses, and some journal articles and books.

The students (in a group of 15-20) were asked to sign up for one of the physicists, and read up on their involvement before, during and sometimes after the Manhattan project. Towards the end of the course we then made a very informal roleplay, where I provided a timeline as a plan for the lesson, and the students took turn in the involvement of "their" physicist. Some chose a detached approach, but many did their presentations in first person, some even dressed up. The informal character of the class made it natural to stop for discussions at any time. The audience was only ourselves. Discussions of the responsibilities of scientists become more interesting and thought-provoking on a backdrop of historical events and the reflexions from those involved. The roleplay opened for ethical discussions through the voice of another person, which are often easier. Many of the students also remarked on the deep impression made by the discovery of how much the physicists had achieved already at a young age.

Socio-scientific issues, such as this one, are multidisciplinary in their character. In a school situation, a possibility would thus be to do such a project together with, e.g., the history and/or English teacher. A more ambitious approach could involve a drama teacher and aim for a performance for another class or at a school open-house day. Mikkel Kofoed describes how the decision to drop the bomb has been used in a roleplay in secondary-school classroom situations. [5]

One might argue that the Manhattan project is not really part of physics, but could and should be left for the history teacher, if at all included. However, this approach could easily add to the image of scientists as lacking conscience and concern for society and to maintain or widen the gap between "the two cultures". From a physicist's point of view, the roles, thoughts, and actions of our older colleagues are of particular interest.

I present below a brief summary of what may be included and references to useful sources. Wherever possible, I have provided WWW-links, because I have found that this considerably facilitates the administration of the task. I have made a personal choice of quotes from much longer texts. I have tried to find examples of physicists struggling with the questions of the role of physics and physicists. Are the quotes representative? Find out! An important aspect of this project is to develop an awareness that one need not depend only on textbook or other presentations, but that it is possible to go back to original sources and form more independent opinions. I strongly encourage you to make use of the richness in internet access and read the original documents for yourself and let your students have a chance to read the previously top secret documents and hear some of the voices from the history of physics.

Ideas, politics and adventures

The photos [6] from the early Solvay conferences show the key physicists of the 1920's getting together for discussions about the fundamentals of quantum physics, laying the ground for our understanding of atoms and nuclei. This period is delightfully described in George Gamow's "Thirty years that shook physics" [7], that gives a human side to the results presented in textbooks. The Nobel museum ( also has extensive information on the life and work of many of the physicists involved.

The development in Europe during the 30s changed the lives of many people, including scientists. Both before and during the war, many physicists were forced to move abroad. When fission of uranium was discovered in 1938, in experiments prepared by Hahn, Meitner and Strassmann, Lise Meitner was already exiled in Sweden. The explanation was found while her nephew Otto Robert Frisch visited her in December 1938. This story is told in many sources [8] and has even reached some textbooks.

Victor Weisskopf describes how "Bohr traveled every year to the United States ' to sell his Jews to American universities,' as we called it" [9]. Weisskopf came to the US in 1937, and was impressed with how the new country welcomed it refugees. In 1941, Heisenberg visited Bohr in Copenhagen, when Denmark was occupied. This visit was in focus in Michael Frayn's play "Copenhagen" from 1998 [10] and is also discussed in many other sources. We may know the "initial and final states", but a detailed knowledge of the interaction is inaccessible. Their accounts of the discussion differ, but it is clear that it related to the possibility of using fission to create a powerful bomb - and that a deep friendship and creative relation was shattered.

In 1943, Bohr himself fled from Denmark. Although he did not take up residence at Los Alamos, he "made several extended visits [during which] he showed a vigorous interest in both theory and design and acted as a scientific father confessor to the younger men ... His real function there was that he made the enterprise which looked so macabre seem hopeful" [11]

Many physicists' flights include adventures; - when Bohr flew from Stockholm to London in the bomb bay of the plane, he fainted from lack of oxygen. Enrico Fermi, whose wife was Jewish, never returned to Italy after the Nobel prize award ceremony, but continued directly on to New York.

Los Alamos

"Because of the danger that Hitler might be the first to have the bomb, I signed a letter to the President which had been drafted by Szilard. Had I known that the fear was not justified, I would not have participated in opening this Pandora's box, nor would Szilard. For my distrust of governments was not limited to Germany." Albert Einstein [12]
The Manhattan Project brought together a remarkable collection of the leading physicists of the time. Many of the names we recognize from groundbreaking works presented in physics textbooks. It marks the first large-scale physics collaboration. The appointment 1942 of Robert Oppenheimer as the scientific leader
"was a marvellous choice. Los Alamos might have succeeded without him, but certainly only with much greater strain, less enthusiasm, and less speed. As it was, it was an unforgettable experience for all the members of the laboratory." Hans Bethe [13]
The Los Alamos site was an exciting brewing pot of creative brains focussing on very difficult problems, involving both theoretical challenges, technological development, logistics and numerics.

For today's generation, brought up with easily accessible computing power, it is hard to understand how advanced numerical computing could be possible with mechanical calculators, slow CPUs, small memory capacities accessed with punch cards. Nevertheless the Los Alamos period marks an intensive development of numerical computing. E.g., Feynman worked out a technique to run several calculations in parallel on the punched-card machines and von Neumann formulated ways to translate mathematical procedures into a language of instructions for the early electronic computers [14].

The historical accounts of the work at Los Alamos rarely mention any women involved in the project, except possibly as wives and participants in the array of people forming an assembly line for numerical calculations, set up by Feynman and Metropolis [15]. In fact, at least 85 female scientists and engineers helped design and construct the atomic bomb [16] , including Chien-Shiung Wu and future Nobel laureate Maria Goeppert-Mayer, who was invited to Los Alamos by Edward Teller.

As the scientists gathered for the Trinity test, the sciencist placed bets on the explosive power of the "gadget". Edward Teller picked the highest with 45ktons of TNT, Hans Bethe placed his bet at 8kt, Robert Oppenheimer went lower, 800 tons, Norman Ramsey went lowest: zero. Isidor Rabi came late and made the last bet: 18 kilotons.[17]

The Events at the Trinity Test Site

"Suddenly, there was an enormous flash of light, the brightest light I have ever seen or that I think anyone has ever seen. It blasted; it pounced; it bored its way right through you. It was a vision which was seen with more than the eye." I I Rabi [15]
The test at Jornada del Muerto created unforgettable memories and thoughts in all who witnessed it. Stanislaw Ulam [18] who remained at Los Alamos, observed "You could tell at once they had had a strange experience. You could see it on their faces. I saw that something very grave and strong had happened to their whole outlook on the future."

The physicists' experiences in connection with this explosion have been described in various essays and other contexts. James Gleick, in his Feynman biography "Genius" [15] writes: "Feynman tinkered with radios again at the century's big event. Someone passed around dark welding glass for the eyes. Edward Teller put on sun lotion and gloves. The bomb makers were ordered to lie face down, their feet toward ground zero, twenty miles away, where their gadget sat atop a hundred-foot steel tower. .... Then, suddenly, music, the eerie, sweet sound of a Tchaikovsky waltz floating irrelevantly from the ether. It was a shortwave transmission on a nearby frequency, all the way from San Francisco. The signal gave Feynman a bench mark for his calibrations."

In a un-classified eyewitness account from 8 days after the explosion Weisskopf recalls [19]:

After about three seconds its intensity was so low I could remove the dark glass and look at it directly. Then I saw a reddish glowing smoke ball rising with a thick stem of dark brown color. This smoke ball was surrounded by a blue glow which clearly indicated a strong radioactivity and was certainly due to the gamma rays emitted by the cloud into the surrounding air.

For many of the physicists, the initial reaction was excitement over a spectacular demonstration of the successful "technologically sweet" joint effort leading up to "the gadget", as it was known: "[W]e started for a good reason, then you're working very hard to accomplish something and it's a pleasure, it's excitement. And you stop thinking, you know; you just stop." [4, p136]. However, many of the descriptions also reflect the tension between the physical and emotional experience. Gleick [15] tells us: "The yellow-orange sphere surrounded by a blue halo - a color that Weisskopf thought he had seen before, on an altarpiece at Colmar painted by the medieval master Mattias Grünewald to depict (the irony was disturbing) the ascension of Christ". Gleick also tells how "when the hot clouds dissipated, Rabi felt a 'chill which was not the morning cold'".

Enrico Fermi's wife Laura found that when he came back later that day, he seemed "shrunken and aged, made of old parchment, so entirely dried out and browned was he by the desert sun and exhausted by the ordeal" [18].

Fermi's eye-witness account shows him always ready to perform estimations:

About 40 seconds after the explosion the air blast reached me. I tried to estimate its strength by dropping from about six feet small pieces of paper before, during, and after the passage of the blast wave. Since, at the time, there was no wind I could observe very distinctly and actually measure the displacement of the pieces of paper that were in the process of falling while the blast was passing. The shift was about 2 1/2 meters, which, at the time, I estimated to correspond to the blast that would be produced by ten thousand tons of T.N.T. [19]
Rudolf Peierls comments: "I am not sure for what I admire him most - his ingenuity in thinking of the method, or his control in letting the scraps of paper go at the right time." [20]. Later, data from various instruments gave a more accurate result, about 19 kilotons. Rabi won the bet!

The Decision

One month before the Trinity test, a scientific panel, consisting of Compton, Lawrence, Oppenheimer and Fermi presents "Recommendations on the immediate use of nuclear weapons" [21], noting that the scientists are not unanimous and that
With regard to these general aspects of the use of atomic energy, it is clear that we, as scientific men, have no proprietary rights. It is true that we are among the few citizens who have had occasion to give thoughtful consideration to these problems during the past few years. We have, however, no claim to special competence in solving the political, social, and military problems which are presented by the advent of atomic power.

In Chicago a committee chaired by James Franck, discussed in considerable detail the consequences of an armament race and possibilities for international control and agreements. They recommended that " a demonstration of the new weapon may best be made before the eyes of representatives of all United Nations, on the desert or a barren island" [22].

In early July, Szilard, who was part of the Franck committee, circulated a petition which was signed by physicists at Chicago and, some days later by physicists at Oak Ridge [23], totalling 137 signatures. (At Los Alamos Edward Teller chose not circulate Szilard's petition.)

Discoveries of which the people of the United States are not aware may affect the welfare of this nation in the near future. The liberation of atomic power which has been achieved places atomic bombs in the hands of the Army. ...
In the cover letter to the colleagues at Oak Ridge, Szilard wrote
However small the chance might be that our petition may influence the course of events, I personally feel that it would be a matter of importance if a large number of scientists who have worked in this field went clearly and unmistakably on record as to their opposition on moral grounds to the use of these bombs in the present phase of the war.
They were soon to know that the petition was unsuccessful.

The responsibility of a scientist

With the background above, we can understand Oppenheimer's comments:
A scientist should assume responsibility for the fruits of his work. I would not argue against this, but it must be clear to all of us how very modest such assumption of responsibility can be, how very ineffective it has been in the past, how necessarily ineffective it will surely be in the future. [24]
Could scientists be held responsible for the way results are used? Should certain areas of science be avoided because of possible destructive use? After all, what has been discovered can not be undiscovered. Should allowable fields be regulated - and if so, who should decide? Who can predict the possible outcome of different investigations? At what stage should work be stopped? There are many difficult questions, which are not, in themselves, of physical character. How could Einstein have known that his famous equation, E=mc2 would come to be associated with mass destruction? In the view of a historical situation, with strong emotional load, opinions may be easier to form before considering the details. However, looking into a chain of events should help students develop more balanced views. Expressing views through the voices of others can also help to widen the range of discussable views in a classroom situation.

The true responsibility of a scientist, as we all know, is to the integrity and vigor of his science. [24]
Is this sufficient? Oppenheimer's assertion is likely to provoke discussions. The American Physical Society and Institute of Physics codes of ethics [25], focus mainly on aspects related to various aspects of "misconduct". Many engineering societies include a concern for other aspects: Engineers use "their knowledge and skill for the enhancement of human welfare" [26] and include also a consideration of the consequences in their codes. A stronger Code of Ethics for Scientists was formulated in 1984 by a group of scientists at Uppsala [27]

Still, the consequences of fundamental physics research are often hard to predict. Although, as a post-doc at University of Washington 1978-80, I was financed by the Department of Energy, the work on methods for relativistic many-body calculation in connection with parity non-conservation seemed far removed from application. However, some years later, when we were developing methods to treat correlation effects, dealing with heavy two-electron ions as test cases, we found that numerical results coming out were sought after by the SDI - the "star wars" initiative.

Is physics human?

Being a physicist is a wonderful privilege, giving you the opportunity to meet and interact with many dedicated people with strong personalities and you can also see how many of them grow old with a maintained creativity and interest in physics and life.

The names of the Los Alamos physicists occur again and again in textbooks and in groundbreaking papers. Their names have become names of effects, approximations and equations, e.g., Feynman diagrams, Bethe logarithm and the Bethe-Salpeter equation in quantum electrodynamics mechanics, the Born- Oppenheimer approximation in molecular physics, the Rabi frequency, the Franck-Hertz experiment, the Jahn-Teller effect, the Fermi-distribution, fermions, ... Often the name becomes so closely related to the effect that we tend to forget that it refers to a person. In my own research, I have worked with the Bohr-Weisskopf effect, due to the distribution of magnetization in the nucleus. I have heard Victor Weisskopf talk about nuclear disarmament but also, e.g., tell the story of a visit to Israel where he learned from a Kabbalist that the integer 137 (which is very close to the inverse over the dimensionless fine structure constant) means - Kabbalah. I have read many of Weisskopf's texts, but only with conscious effort do I make the connection between the person and the different aspects of his work.

Let us not forget to show our students that physics and physics research is a creative and challenging human activity, where people interact not only through equations and fields but also through their personalities.

"It troubles me that the public sees physics only as the mother of technology ... No one any longer pays attention to - if I may call it - the spirit of physics, the idea of discovery, the idea of understanding. I think it's difficult to make clear to the non-physicist the beauty of how it fits together, of how you can build a world picture, and the beauty that the laws of physics are immutable." [28]

In 1988, I spent three months at a workshop at the Institute for Theoretical Physics in Santa Barbara. One of the participants in residence was Hans Bethe. As I read the description [15] of Bethe as the Battleship and Feynman as the mosquito boat, I recall how Bethe's former student, Gerry Brown, always left the coffee room, following closely in the wake as soon as Hans Bethe left. Rudolf Peierls might have appeared old and fragile but he was telling us about physics and of Los Alamos - without manuscript or other aids. During a whale watching trip he was standing with his binoculars, always at the best viewing spot, his curiosity as strong as ever.

Richard Feynman was on the list of participants, but disease and death prevented his participation. Also Rabi, whom I have met at several conferences, died that spring.

Scientists in School?

Direct contact with the Los Alamos physicists is, of course, not an option for our students. But in reading the documents related to the Manhattan project, and sometimes listening to recordings, they can get closer to the persons behind textbook names and learn how great men have dealt with difficult questions.

The Manhattan project abounds with interesting aspects and can be used as examples for students in many different ways. In my first contacts with general courses in teacher education in our university, I was a bit taken aback by a common attitude to science and technology as a "root of all evil", with the bomb as a prime example. I decided to have the students learn more about the development. A few times I had the students prepare different mini-lessons about different aspects: History, politics, physics, biology, ethics, where each group of students could make use of their speciality. The first time I used it in physics courses in the teacher programme, I had the students choose different aspects and tell the rest of the class. I have also asked one group of students to do a short dramatization, staging an imagined dinner conversation taking place an evening before a conference, when some of the physicists got together again, sharing reminiscences from Los Alamos. All these approaches have worked reasonably well, although, on occasion one or two students might drift deep into weapons technology or military strategies. With open-ended tasks, it is always a question of subtle balance to give the students freedom to feel ownership of their work, and still provide sufficient instruction to help them maintain the intended focus.

I found that asking the students to choose one physicist and study his/her work, actions and reactions brought a good focus to their preparations. The human aspects were inevitable - but so was physics. Seeing the same event through the eyes of different physicists gave a good mixture of repetition and variation. By following the same physicist through different periods the connection between physics, life and society were more accessible.

Science and Society

New frontiers of the mind are before us, and if they are pioneered with the same vision, boldness, and drive with which we have waged this war we can create a fuller and more fruitful employment and a fuller and more fruitful life. [29]
These optimistic words written in November 1944, are part of the letter from president Roosevelt to Vannevar Bush, which led to the July 1945 report Science - the Endless Frontier laying the ground for many years of research policy and to the establishment of the National Science Foundation (NSF). After the war, many physicists also played important roles as science advisors.

The period after the war showed some dark sides of the relation betweeen physics and society. After the Second World War Edward Teller concentrated on developing the hydrogen bomb, leading to a first explosion in 1952. The documents from the McCarthy era and the Oppenheimer affair show us the action of the Los Alamos physicists, with pride, integrity and conflicting loyalties, in a slightly different context where scientific openness and judgement clash with national security issues [30]. Although sufficiently long ago to be un-classified, this type of problem is not outdated. However, the post-war period also offers many examples of concerned physicists getting involved with society-related question in a much more active way than before. Many physicists worked in different ways to reduce the nuclear threat.

The Federation of Atomic Scientists (later, Federation of American Scientists, FAS) was formed in 1945 by atomic scientists from the Manhattan Project "who felt that scientists, engineers and other innovators had an ethical obligation to bring their knowledge and experience to bear on critical national decisions, especially pertaining to the technology they unleashed - the Atomic Bomb" [31]. The Bulletin of the Atomic Scientists, also founded in 1945 continues to "educate citizens about global security issues, especially the continuing dangers posed by nuclear and other weapons of mass destruction, and the appropriate roles of nuclear technology" [32].

In 1955 Bertrand Russell and Albert Einstein launched a manifesto [33] asking scientists of every country to meet to devise ways of avoiding nuclear war. One of the 11 signatories was Joseph Rotblat, who founded the Pugwash Conference in 1957. Rotblat and the Pugwash conferences were awarded the 1995 Nobel peace prize.

What is the role of physics in society? Physics has unleashed nuclear energy and there is no going back. Victor Weisskopf, in the preface to his book "The privilege of being a physicist" still maintained an optimism concerning the role of scientists:

Science is a truly human concern; its concepts and language are the same for all human beings. It transcends any cultural and political boundaries. Scientists understand each other immediately when they talk about their scientific problems; it is therefore easier for them to speak to each other on political or cultural questions and problems about which they may have divergent opinions. The scientific community serves as a bridge across boundaries, as a spearhead of international understanding. [34]


I would like to thank many colleagues, both at the physics department and at the department of education, in particular Aadu Ott, for inspiration to try alternative forms of teaching and assessment. Helpful comments from physics teacher Conny Modig, professors Aant Elzinga and Gunnar Tibell as well as from the editors, were very much appreciated.


  1. Weisskopf, V F 1985 Fourty Years After : Thoughts of a Nuclear Witness, reprinted in The privilege of being a physicist, 1989
  2. Sjøberg, S 2003 Science and Technology Education Current Challenges and Possible Solutions, in Jenkins, E (ed) Innovations in Science and Technology Education Vol VIII, Paris, UNESCO, Sjøberg, S 2002 Science for the children? - Report from the SAS-project, a cross-cultural study of factors of relevance for the teaching and learning of science and technology,
  3. Horowitz J, 1998, Building Bombs, Talking Peace: The Political Activity of Manhattan Project Physicists B.A. Thesis History and Social Sciences, Harvard,
  4. Feynman, R P (ast told to R Leighton) 1985 Surely, You are Joking, Mr Feynman - Adventures of a Curious Character, New York: WW Norton
  5. Kofoed, M, Physics Education (this issue)
  6. Photos from the Solvay conferences can be found e.g. at the Emilio Segrè visual archives at the Americal Institute of Physics, A short movie from the 1927 conference is available at
  7. Gamov G 1966 Thirty Years That Shook Physics: The Story of Quantum Theory
  8. Sime R L 1996 Lise Meitner: A Life in Physics, U. California Press
    Rife P 1999 Lise Meitner and the Dawn of the Nuclear Age (Birkhäuser).
  9. Weisskopf, V F 1989 Thoughts of a Hitler refugee, in The privilege of being a physicist, p 203
  10. Frayn M 1998 Copenhagen, Methuen Drama, see also e.g.
    Ziman J 1999 An evening with the Bohrs, Physics World, June 1998,,
    Durani M 2001 Secret Letters cast light on Copenhagen, Physics World, November 2001
  11. Pais A 1994 Niels Bohr's Times - In Physics, Philosophy, and Polity, p497
  12. American Institute of Physics, Einstein Exhibit,
  13. Bethe H A, J. Robert Oppenheimer, Obituary published at
  14. Los Alamos National Laboratory 1995 Evolving from Calculators to Computers, 50th Anniversary Article,
  15. Gleick, J 1992 Genius: The Life and Science of Richard Feynman, Pantheon, excerpts available on-line from Gleick's site
  16. Howes R H and L. Herzenberg C L 2000 Their Day in the Sun: Women of the Manhattan Project, Temple University Press,
    Contributions of Twentieth-Century Women to Physics,
  17. Moody S, Proving Ground, An Albuquerque Journal Special Reprint, July 1995,
  18. Fermi L 1995, Atoms in the Family : My Life with Enrico Fermi, cited in Kitchens S A 2005 1945; Dead old parchment,
  19. Trinity Test, July 16, 1945, Eyewitness Accounts, transcribed by G Dannen,
  20. Peierls R 1985 Bird of Passage; Princeton, p202
  21. Compton A H, Lawrence E O, Oppenheimer J R and Fermi E 1945 Recommendation on the Immediate Use of Nuclear Weapons, June 16 1945, transcribed by G Dannen,
  22. Franck J et al 1945, Report of the Committee on Political and Social Problems Manhattan Project "Metallurgical Laboratory" University of Chicago, June 11, 1945 (The Franck Report), Transcription by G Dannen at
  23. Szilard L 1945 Petition, Transcribed by G Dannen at, and
  24. Oppenheimer J R, 1947, Physics in the Contemporary World", MIT Lecture, published in Great Essays in Science, Meridian (M. Gardner, ed.), 1994, p205
  25. Statements of Ethics by the APS and by the IoP, html
  26. Center for the Study of Ethics in the Professions at IIT, Codes of Ethics Online - Engineering,
  27. The Uppsala Code of Ethics for Scientists, available on-line at, see also Gustafsson B, Ryden L, Tibell G, and Wallensten P Focus on: The Uppsala Code of Ethics for Scientists, Journal of Peace Research, Vol. 21, No 4, 1984
  28. Bethe H A 1991 The Road from Los Alamos , see also
  29. Science - The Endless Frontier, Bush V
  30. The Atomic Archive, includes transcripts of testimonies in the Oppenheimer Affair.
    See also and
  31. Federation of Atomic Scientists
  32. Bulletin of the Atomic Scientists,
  33. Russell B and Einstein A 1955 The Russell Einstein manifesto, einstein-manifesto.htm
  34. Weisskopf, V F 1989 The privilege of being a physicist, p7-8


1938 Fission of Uranium discovered (Hahn, Meitner, Strassmann, Frisch)
1939 2 augusti, Letter to President Roosevelt (Einstein, initiated by Szilard)
1941 Heisenberg visits Bohr in Copenhagen
1942 23 September, Oppenheimer appointed scientific director of the Manhattan Project at Los Alamos
1942 2 december, The First Controlled Nuclear Reaction, Enrico Fermi, University of Chicago reactor
1945 3 July, Szilard petition
1945 16 July, Trinity test - world's first atomic blast
1945 6 + 9 August, Hiroshima and Nagasaki
1949 Start of "Oppenheimer Affair"
1952 First Hydrogen Bomb explosion
1953 Oppenheimer faces a security hearing that ultimately recommended that his security clearance be ended

More detailed timelines can be found, e.g. at; and at the WWW-pages from the National Atomic Museum in New Mexico,

The author together with Norman Ramsey discussing thallium isotope shifts during a conference in Stockholm in 1987. (Photo: Ingvar Lindgren)

Ann-Marie Mårtensson-Pendrill is professor in physics at Göteborg University, with a background in computational atomic physics. She is a fellow of the American Physical Society and of the Institute of Physics. Her teaching involves engineering, physics and teacher programmes and she is involved with different forms of informal learning, including amusement park physics.