Alan Cottey: UEA Personal Web Pages
(Edited from notes of a lecture given at La Trobe University, Victoria, Australia)
First degree textbooks in nuclear physics emphasise the basic, or 'pure', physics of the subject. Reactor physics is also treated but the other major application of nuclear physics is not. Further, the texts are remarkably seamless - the asymmetry does not stand out.
Does this matter? I argue that it does. As long as significant knowledge of nuclear weapons is confined to nuclear weapons professionals, the mystique surrounding the subject and the isolation of the 'priesthood' will endure. It would be helpful if all physics BSc students addressed, in their nuclear physics course, the technical, political and moral aspects of nuclear weapons. Such study need not claim 'the answers' but it should approach the subject 'head-on', thereby breaking a taboo. The present project evolved from a nuclear physics course I gave to BSc physics students, in the 1980s and 1990s. It comprises a close textual analysis of English-language first degree textbooks in nuclear physics. The seamlessness I mentioned above is found to depend on subtle choices of language and presentation.
The Personal is Political: In the early 1950s, when I was about 15, I saw a picture of an H-bomb mushroom cloud taking the full width, but not much height, near the top of the front page of a newspaper. That image has never left me. To this day I don't understand what cue or cues made it possible to judge the scale, but somehow one could tell instantly that this was far beyond the A-bomb. Although privately concerned about this, I did not feel able to address it openly, or even discuss it seriously with other people. I became a head-down physicist. I was clear that I did not want to be connected with nuclear weapons R&D and even at an early age I believed that nuclear power could not be decoupled from weapons. In my secondary school studies and first and second year of physics BSc studies I found nuclear physics interesting. It did not have the glamour of quantum mechanics, relativity or particle physics, but its social significance was something I wanted to take seriously, even if I did not have the confidence to 'come out' in the anti-nuclear weapon campaign of the time. I considered, even then, that it was important for physicists to be educated in the physics of nuclear weapons, rather beyond the (UK) A-level standard. I looked forward to the in-depth nuclear physics course in the third year. In the event, I found that course hard to generate enthusiasm for. The curious fact that I found this particular course dry stuck in my mind. For decades I could never figure out why. I'll come back to this.
I became a lecturer in physics and did research in condensed matter physics and teaching in a wide range of branches of physics. I still had a head-down attitude to the great moral problems of the use and misuse of science and technology - not being indifferent but being afraid that engagement in them would make it impossible to reach 'take-off speed' in academic research projects. In the mid-seventies, however, the long slumber of the anti-nuclear-weapons movement came to an end. Especially influential for me, I recall, were numerous articles in the New Scientist by Frank Barnaby. He had worked at the Atomic Weapons Research Establishment (as it was then called) at Aldermaston. The poacher became a gamekeeper, and rose to a head gamekeeper's position (Director of SIPRI, the Stockholm International Peace Research Institute). If you wanted to be scared by the state of the nuclear arms race, Frank was your man. In those days there was some pretty apocalyptic talk about - which in my view had, and has, an entirely rational basis. (Later, most of those concerned about nuclear arms realised that you can't frighten people into listening.)
I became active, in a modest way, in campaigns against the arms race. This was all very well, but I felt it paradoxical that a physicist should not feel able bring a practical concern about the survival of everyone into his teaching. I offered to teach the nuclear physics course. I knew that nuclear weapons were embarrassing in the context of advanced physics education but I decided to commit a solecism and teach the subject as if they existed. I did this for about ten years.
The Nuclear Physics Course with Nuclear Weapons in: I found preparing and presenting it remarkably difficult. The cold war was in an unstable state. In education, it was not done to mention nuclear weapons in the wrong context. Physics education was definitely a wrong context. Physics was describing the physical world. Describing the social world was done in another department and thinking about right and wrong in another department again.
Information about nuclear weapons is not, of course, so readily available as other nuclear information. That however is not a real problem for a teacher willing to do a bit of homework. The real difficulties were cultural. Nuclear weapons were off limit and it was difficult to find the right way to bring them within limits.
Textbooks: That a suitable textbook did not exist was of course not surprising and its absence was not a significant obstacle. I did, however, get interested in the textbooks that existed and investigated exactly what it was about them that was peculiar, ie made them different to textbooks in other areas of physics. I surveyed all the (English language) nuclear physics texts I could get to see.
My mind went back to the third year nuclear physics course that a keen student had found unaccountably dry. I felt it had not been the teachers because they had been young, talented and lively. In the departmental tea room, distinguished professors engaged in sober discussions did their best to ignore the pellets of silver foil that fell on them and their tea from the other side of the room - projected by the young turks, Don Perkins and Peter Fowler.
Green: No, it must have been the textbook. It was A E S Green's 'Nuclear Physics' (McGraw-Hill, 1955). I think I will be able to get across much of what I found out about the teaching of nuclear physics by commenting on this book in detail. Then I will gradually spread our attention to the features I have found characteristic of first degree nuclear physics textbooks in general. I hope to show why an interest in these features is not mere pedantry. On the contrary, they are connected with humanity's lack of adequate response to our new capacity for mass destruction. (In case you are thinking that this capacity is hardly new, I point out that our cultural and psychological behaviour, in relation to nuclear weapons, has changed remarkably little, over the whole of the nuclear era. This, and the dire consequences of further use of nuclear weapons, imply that a half-century is, for the discussion in hand, a short time.)
From my later vantage-point as an experienced physics teacher, concerned about the social implications of science, I could see why Green's book seemed dry. Even by the standards of many other nuclear physics textbooks it is laconic and detached. I believe the style has to do with the quid pro quo between nuclear physicists and their nation-states. The physicists got good funding, and in return they delivered a cadre of competent and reliable experts. The connections and lack of connections between basic physics, reactors and weapons are carefully, though almost certainly unconsciously, controlled. To convince you of this, I will give a few of the many examples of telling details that I have amassed in the course of a survey of nuclear physics textbooks.
The principal way in which Green differs from many, though by no means all, other nuclear physics textbooks is in excluding applications and in doing so consistently, ie the book has almost nothing on reactors.
Green does have a few lines here and there which mention or relate to reactors. They have some curious features. These features are not obvious, otherwise they would of course never get past the first draft stage. (I do not imply by this that authors, referees and editors practice censorship consciously, but rather that it is 'just natural' to remove solecisms.) Taken individually, the features seem trivial. On analysing many nuclear physics textbooks, however, one finds the same features coming up again and again, and can see their significance.
Hamlet without the Prince (a feature of almost all of the texts). In Green's book, in a section on ion sources, one reads (p86 line8ff) "A form of mass spectroscope known as the calutron was developed extensively during World War II in connection with the electromagnetic separation of U235 from U238." That is all. I believe that the occasional laconic phrase like this serves a purpose. Complete silence would be noticed and open the author to a charge of self-censorship. Readers will know what the passage refers to, but further enquiry is somehow blocked off.
Vaguespeak: There is a section (2 1/2 pp: p313ff) titled 'Sustained Fission Reactions'. Like many other nuclear physics text authors, Green uses some language which is strange, though this does not stand out for the normal reader. 'Sustained' in this section logically can mean a bomb, since a microsecond is a long time for a fast neutron reaction, but any reasonable use of language would take 'sustained' to imply a reactor. That the bomb is meant to be included is shown by the laconic remark (p313 lines9-10) "The fact that these parameters were found suitable [for a sustained process] is recorded in history."
When Plutonium is introduced it is described as a "fissionable fuel", and this is in a sentence describing its production in a reactor. Thus, normal usage applies - the word 'fuel' implies reactor fuel. The weapons significance of Plutonium is bypassed. Only by sophistry could anyone claim that the meaning includes 'weapon fuel'.
These odd, imprecise or vague usages of language are very common in nuclear physics textbooks whenever the dread 'thing' casts its shadow. If this should seem an exaggerated claim, recall that a feature of 'normal physics' is its precision and textbooks are written about established matters with much care in order to be as clear as possible for the beginner. Nuclear physics textbooks achieve a high level of coherence and clarity in areas not under the 'shadow'.
Fusion: Another odd feature in Green, which is not readily picked up because it is an absence, is that fusion is not mentioned anywhere, neither the basic physics nor thermonuclear reactions (in stars, in weapons or for power). (The reaction H3(d,n)alpha is however mentioned - as a source of neutrons.) This feature is surprisingly widespread. It is the more remarkable in view of the fact that a number of really minor phenomena commonly find space in the texts. Green, for example, has a short passage (p309 lines8-13) on Ternary Fission. For books devoting several hundred pages to the basic physics of nuclei to say nothing at all about fusion cries out - to this analyst, at least - for an explanation.
Then and now: Some of you may be thinking - what's the point of going on at length about a book published in 1955? That can have no relevance for today's textbooks. This is not so. Most, possibly all, of the features I have highlighted may be found in today's books. In fact, the historical trend in nuclear physics texts, since August 1945, is instructive. The earliest textbooks are, on the whole, more frank about nuclear weapons than those from, roughly the mid '50s to the early '80s. The two editions of the widely used book Introductory Nuclear Physics by D Halliday (Wiley, 1e 1950, 2e 1955) exemplify this.
From the mid 1980s, the preceding concern of a wider public about the state of the nuclear arms race was reflected in a few textbooks for students of nuclear physics. J M Pearson's 'Nuclear Physics: Energy and Matter' (Hilger, 1986) is especially significant because it is explicitly designed to meet the needs of students who will not specialise later in nuclear physics. He refers to the unfortunate "spectacle of large numbers of physics graduates leaving the universities and going out into the wide world unable to make any scientific contribution to the great public debate on the future of nuclear energy, a debate for which it is imperative that there be as much informed input as possible, so crucial is it to the future of mankind." (preface, p xi lines 8-13).
This seems to me to be a step diagonally forward. The future of mankind gets more than token attention in Pearson's preface; but why does he refer to 'nuclear energy', a phrase which almost always implies 'controlled'? It is true that Pearson does give much more meaningful coverage of nuclear weapons than any preceding textbook. (My survey is restricted to books in English, including translations into English.) The principal difference between Pearson's book and earlier ones is, as he says, that he has written a book for all the students in a physics class, most of whom will not go on to practice nuclear physics professionally. It seems to me that Pearson wanted to engage in the "debate ... crucial ... to the future of mankind" but he encountered what I will discuss, a little later, as the invisible barrier.
K S Krane's 'Introductory Nuclear Physics' (Wiley, 1988) is the text which goes furthest in acknowledging the importance of nuclear weapons. It has a 5 page section (pp520-5) titled 'Fission explosives' and a 4 page section (pp553-7) titled 'Thermonuclear weapons', with about half of the coverage being on the effects of nuclear weapons and the scale of the arsenals. This is very different from any other nuclear physics textbook of which I am aware. Yet even those sections amount to little more than 1% of the book.
The 1990s: One might suppose that after Pearson and Krane had broken the taboo, nuclear weapons - this matter of life and death - would be within the limits of nuclear physics education. This has emphatically not been the case. Nuclear physics education has followed behind public concern. Both turned their attention away from the problems of nuclear weapons. With the end of the cold war, the dangers have changed, but they are severe. Inattention to these dangers is most imprudent.
Diverting attention: In some nuclear physics texts, as in the wider culture, mere inattention is not enough. Positive diversion of attention occurs. S M S Wong, for example, in the preface (p viii) of 'Introductory Nuclear Physics' (Prentice-Hall, 1990) justifies a study of the subject for its intrinsic interest, for its connections with particle physics and condensed matter physics and because "nuclear physics may be usefully applied to other fields: chronology in geophysics and archaeology, tracer element techniques and nuclear medicine, just to name a few."
Asymmetry: Textbooks which restrict themselves strictly to the physics of nuclei at the first degree level are in a minority. Most include a discussion, often quite detailed, of reactor physics (and sometimes a little engineering as well). But - if reactors are in, why not weapons? Both are applications; both provide useful illustrations of the basic physics principles; and both are important. The answer is obvious - or is it? Is because nuclear weapons are unpleasant and frightening? Or because of the secrecy of the details, and - related to this - their importance to the nuclear weapon states?
If one challenges this asymmetry, one finds difficulties which at first appear mysterious - invisible barriers. Leaving aside the obvious resistance, in oneself as well as in others, to dealing with a topic that almost everyone finds disagreeable, one may ask of the textbooks: how do they manage to be so seamless? The treatments given seem proper and even inevitable? One has to be committed to analysis of the problem of nuclear weapons if one is to take the trouble to look for the almost invisible joins. Let me describe just a few of the joins I found ...
Authors usually cover themselvesby mentioning nuclear weapons extremely briefly, often in a few words. N A Jelley (Cambridge U P, 1990) for example in 'Fundamentals of Nuclear Physics' has 30 words on fission weapons; fusion weapons, however, might as well not exist. Jelley's book, indeed, reveals an unusually strong compartmentation of thought. In his preface he writes (p xiii) "... parts of nuclear physics ... have particular significance in other fields: for example, fission in nuclear power, fusion in astrophysics and radioactivity in biological tracer techniques."
From Physics to Reactors: In almost all the texts, there is a natural-seeming progression from the physics of fission to a more or less detailed discussion of reactors, with a few lines, or even only a few words, on weapons. Why does this seem natural? After careful examination of many texts, I have come to the conclusion that two devices are widely used, probably unconsciously. One is to make an earlier reference to reactors as neutron sources. This is done for example in E Segre's 'Nuclei and Particles' (Benjamin, 1964). The other is to make delayed neutron emission by fission products a direct link between the physics of fission and thermal reactors. (Such an exposition is 'safe' because delayed neutrons have no relevance for explosive weapons.) This is done in, for example, S B Patel's 'Nuclear Physics' (Wiley Eastern, 1991).
Plutonium: The 'need' to pass smoothly from physics to reactors and to avoid getting hung-up on weapons is, I believe, the explanation of notable features on the treatment of plutonium. H Frauenfelder and E M Henley in Subatomic Physics (Prentice-Hall, 1974) say reactors "are used as research tools, for the production of radioisotopes and for the production of power ... Power production may well be the most important function of reactors." (p452). Why the cautious 'may well'? The only candidate, as a rival 'important function of reactors', is conversion of U to Pu. The authors are being economical with the news. What is more, the nearby phrase 'production of radioisotopes' misleads the reader, since that phrase is normally used for small scale applications in scientific research, general industry and medicine, and not for large scale production of Pu.
Conversion is at the heart of the link between nuclear power and weapons, yet there was remarkable ignorance about this, by everyone except nuclear physics professionals, until the revival of the politicised anti-nuclear campaign in the late '70s. Indeed, I have the impression, from the writings and speech of nuclear physics professionals, that even they hardly ever brought U to military Pu conversion into consciousness as they discussed nuclear power.
The so-called Hydrogen Bomb: Fission bombs are dreadful enough, yet fusion bombs can be a thousand times more powerful. I think there is evidence from the nuclear physics texts that the general attitude to the two types of weapon is not that both are equally at the top end of the scale of horror. I believe that most nuclear physics text authors cannot come to grips even with the fact of their existence. The phrase "the so-called hydrogen bomb" is sometimes used, for example by W S C Williams in Nuclear and Particle Physics (Oxford U P, 1991). Obviously the term 'hydrogen bomb' is not scientifically very sophisticated, but I believe that is not the point. The real significance of the appearance of 'so-called' is that it undermines the reality of the fusion bomb.
Even physics text authors cannot be rational under this enormous shadow. How else do we understand why B L Cohen, on p389 of Concepts of Nuclear Physics (McGraw-Hill, 1971) wrote "these so-called thermonuclear reactions"? For here we have a technical term neither more nor less 'so-called' than hundreds of others.
Under the Shadow: Nuclear physics textbooks are in general written and produced to a high standard. It is therefore noteworthy that the standard slips when nuclear weapons are onstage or in the wings. R J Blin-Stoyle (Nuclear and Particle Physics; Chapman & Hall, 1991), in a section on stellar fusion writes "For reactions of this kind to proceed in an, inevitably, relatively infinitesimally smaller fusion reactor on earth requires …". Solecisms this bad are not to be found in more normal contexts.
Misprints are more common in the 'nervy' areas. For example Burcham's 'Nuclear Physics' 2e 1973 refers (p635) to 289Pu. And the standard of exposition drops. In his sophisticated and accurate book Concepts of Nuclear Physics (1971), the eminent nuclear physicist B L Cohen suddenly descends (p407) to "An atomic bomb is basically a fission reactor with a mass very much larger than the critical one"? This manages simultaneously to be wrong and confusing. Wrong, because the mass cannot exceed about 3 times the critical mass, which is hardly 'very much larger'. Misleading, because the proximity of 'reactor' and 'very much larger' will send most readers off on the wrong track, for a controlled reactor does indeed have a mass very much larger that of a bomb.
Responsibility: In this lecture I have focused on some small details in nuclear physics textbooks. Individually, they might well be trivial, but taken together they mean something for a very large question. Can humanity find an adequate response to our new capacity for mass destruction? Physics educators bear a part of the responsibility for the very slow progress that has been made over the last half-century.
The 21st century: Much of the detail of this critique of the nuclear physics textbooks could be perceived as querulous. This would be an error. The motivation for this study is positive. We can create a sustainable society. Education can play a positive part in this, but this does require that teachers help students to face pressing problems, even the most frightening ones.
Alan Cottey
Alan Cottey, University of East Anglia, Norwich NR4 7TJ, UK
The basic version of this page was created in 2000 and the page was last modified on 28 October 2013.