WHEN THE WAR STARTED YOU WERE IN ENGLAND. WHAT WAS IT LIKE FOR YOU THERE BEING A GERMAN EMIGRE WHEN THE WAR BEGAN?

Well, in 1939 when the war broke out I was in England. I was still a German citizen and therefore an enemy alien. That meant at first quite a lot of restrictions before the authorities had time to sort out the different types of Germans. After a while we were... came before a tribunal which expressed confidence and therefore many of the restrictions were dropped. We were again allowed to drive a car and things like that. But we were still... I was still not allowed to work on secret projects. There was in my university a radar project going on for the Navy. And the... my colleague in charge of that wanted me to join this, but that was not allowed. I hadn't been in England long enough for that. So the only — I was of course anxious to do what I could to help against Hitler. And the only thing I succeeded to doing then was to join the auxiliary fire service which was there to reinforce the regular fire service in case of air-raids. And in fact I was present in -- I was on duty I think in... on all the... during all the air raids that took place on Birmingham where I lived.

SO YOU WEREN'T ALLOWED TO WORK IN YOUR FIELD ON PROJECTS THAT WERE CONSIDERED SECRET?

That's right. I was not allowed... to work on secret projects of any kind including radar which was the... one of the main activities in my university.

DID YOU FIND THAT RATHER IRONIC THAT HERE YOU WERE A REFUGEE FROM HITLER'S GERMANY AND YET YOU COULDN'T WORK AGAINST HIM?

I think it was understandable. The... In wartime everybody is under pressure. They have problems and you can't expect them to adjust the rules to suit every... special case of every individual. But of course it was annoying.

NOW TELL ME ABOUT THE REACTION WHEN THE NEWS OF THE DISCOVERY OF FISSION CAME TO ENGLAND. I READ IN YOUR BOOK THAT THERE WERE STORIES IN POPULAR MAGAZINES, FICTIONAL ACCOUNTS OF ATOMIC BOMBS. COULD YOU DESCRIBE THAT?

Well, the impression in the general was of course that now one could make atomic bombs, after all, the speculations of H. G. Wells had predicted that a long time ago. And so people that didn't know too much about physics immediately jumped to the conclusion that this would now be a possibility. Scientists were more cautious of course. And in particular, we had un... understood the argument due to Niels Bohr, the great Danish physicist, who had shown that the fission as it was mostly observed due to... was due to very slow...reaction of very slow neutrons on the very rare isotope of uranium — Only less than one percent of the uranium found in nature has... consists of the light isotope. But that was doing all the fission that was observed. And from that account one could easily convince oneself that in natural uranium, as it was found in nature you could not make an explosion. And we found that on the whole very reassuring.

LET ME ASK YOU TO START BY SAYING SOMETHING LIKE: WHEN WE HEARD THE NEWS OF FISSION...AND THEN GO INTO THE IDEA THAT NIELS BOHR FELT THAT IT WAS NOT GOING TO BE POSSIBLE TO PRODUCE A BOMB...

The... in 1939 physicists got very excited about the discovery of fission by Hahn and Strassmann in Germany. And I had the good fortune that Otto Robert Frisch had just come to Birmingham who had been the first... done the first experiment to prove actually that the interpretation of this new phenomenon was all right. That really the uranium nucleus could be... break up into two parts with a lot of energy coming out. And of course one thought of the possibility of a weapon. However, we also knew from the work of Niels Bohr, the great Danish physicist, that it was not so simple. And he gave arguments which convinced us that in natural uranium — which as it's found in minerals — you could not make a weapon. And we found that very comforting.

COULD YOU TRY TO GIVE US A RUDIMENTARY EXPLANATION OF WHAT FISSION MEANS AND WHY THAT WOULD LEAD A PHYSICIST TO THINK OF THE POSSIBILITY OF A WEAPON?

All right. The story which we which physicists put together from the great discovery of Hahn and Strassmann was that the uranium nucleus... the center of the atom of uranium is as it were top heavy. It's really too big for its own good and tends to split up. But in ordinary circumstances it would be too difficult for it to do so. But when it's hit by a neutron then it gets sufficiently disturbed to allow it to escape and to split into...in two parts. And that releases a lot of energy. It not only does that, but it also produces additional neutrons which in turn can hit and split up other uranium nuclei. And as long as for each neutron that hits a nucleus you get out more than one neutron in the end they can, of course, very rapidly build up. And you get what's known as a chain reaction. And if that chain reaction is sufficiently fast it can in fact build up to an explosion. And that's essentially the story of the bomb.

CAN YOU PICK IT UP FROM THE NOTION OF CHAIN REACTION WE'RE HAVING A SLIGHTLY DIFFERENT SHOT.

All right. You... When the nucleus breaks up, when it undergoes fission, as we say you not only get a lot of energy out, you get also fresh neutrons. And as long as for every neutron that you've used up in breaking up a nucleus you get more than one new neutron coming out you get what's called a chain reaction. The neutrons multiply up very quickly, And if that chain reaction proceeds sufficiently quickly then you can... it can build up to an actual explo... very powerful explosion. And that's essentially the story of the bomb.

COULD YOU SAY JUST A LITTLE BIT ABOUT THE EINSTEIN EQUATION TO GIVE US SOME NOTION OF THIS GREAT MAGNITUDE OF ENERGY THAT COMES FROM THIS LITTLE BIT OF MATTER?

I would prefer not to bring in the Einstein equation. That's the red herring.

OK.

The fission process involves, of course, enormously greater energies than are usually resources. Because, usually, if you burn coal or get energy out of any other chemical reaction you're concerned only with the electron which form the outside of the atom. In fact, only with the outermost electrons. And their energies are usually measured in electron volts which is the energy that an electron gets if you pass it through a field... an electron field involving one volt. And in the chemical reactions you are usually involved with energies of the order of a few elect volts. And it is not surprising because that's how the unit volt got defined. But in the fission process you're involved with the very small nucleus in the center of the atom and that is very much tighter and very much more strongly held together. The energies involved there are measured in millions of electron volts and the in fact the... in the fission process you get out... very many of those at millions of electron volts. And therefore, understandably, if you could cause fission is, say 1 kilogram of uranium you would get something like a hundred million times the energy that you... that you get by burning 1 kilogram of coal. Is that what you wanted?

YES. IT TAKES A WHILE TO EXPLAIN. I'M NOT SURE IT'S THE KIND OF THING... LET'S TRY AGAIN.

OK. I'll try again. In the fission we are..., get enormously greater energies than from other energy sources. In the ordinary chemical reactions, like burning coal, where you're dealing only with the outermost electrons in an atom where as in the nuclear reactions, such as fission we're concerned with the nucleus. That's the very small core of the atom which is very compact and held together by enormous forces involving energies of... a few million to perhaps 50 million times greater than those involving the electrons in the atom. And, therefore, if we could produce fission in... a kilogram of uranium we'll get some, say... 50 million times more energy out than burning a kilogram of coal.

AFTER NIELS BOHR DECIDED THAT HE THOUGHT THE ATOMIC BOMB WAS NOT POSSIBLE, HOW DID YOU AND FRISCH COME TO THINK THAT IT WAS POSSIBLE?

Well... well, we had been comforted by the conclusion of Niels Bohr that in natural uranium could not get a violent chain reaction, a violent explosion. But one day Frisch came along and said, Now, suppose somebody gave you a quantity of separated uranium isotope. The light uranium... so called uranium-235 represents less than one percent of natural uranium. And get... since it's chemical properties are the same, as other uranium it's very hard to separate. But somebody gave it to you, what would happen? Now we discussed this and from the theory of the fission process which Niels Bohr had developed we could make a guess at the how much you would need to produce a chain reaction in the separated uranium. And we were surprised to find how small it was. Only a few pounds. We actually underestimated it a little. But it wasn't the tons that one intuitively had guessed before. And then we said, Well, that's very exciting. Now what would happen? How far would the chain reaction go? And there again, we could get an estimate on the... proverbial back of an envelope. And again to our surprise we found that a considerable fraction of the available energy would be released. We couldn't say exactly how much but certainly enough to make an extremely powerful explosion. And then we said, well this is so important. Particularly it's frightening that the Germans might have realized that too. And the idea that Hitler would have this weapon before anybody else got it was frightening.

COULD YOU THEN JUST BACK UP A BIT AND PICK IT UP FROM THE POINT WHERE THERE WOULDN'T BE AS MUCH MATERIAL NEEDED AS YOU THOUGHT ETC.

When we saw how small the necessary amount would be we then asked ourselves how efficient would be the chain reaction if it took place. And on the back of the proverbial envelope, a rough estimate showed us that a very reasonable proportion of the available energy would come out. In other words, that this would be an explosion of enormous power. And this frightened us. Particularly because we... were aware of the possibility that the German physicists might have understood this too. And the idea of Hitler having such a weapon before anybody else did was most frightening So we decided to write a little memorandum and to send that to the appropriate authorities.

SO LET'S START BACKING UP OVER THE TAIL END OF WHAT YOU JUST SAID ABOUT THE MEMORANDUM. SO WHAT DID YOU DO WITH YOUR RESULTS?

Well, when we realized this situation we decided to write a short memorandum to explain our conclusions and send it to the appropriate authorities. And in that memorandum -- of course first of all we set out the technical case for believing our conclusions and then explained the significance in which we pointed out that there was no defense against this weapon and therefore the only possible response to it was to have that similar weapon yourself and therefore use it as a deterrent. And so it was important to try and produce this weapon even if you are... not proposing to use it yourself as a weapon of war. We pointed out that the radiation associated with the explosion would in most circumstances kill a lot of civilians. And what we actually said in the more general part of the memorandum was this might make it unsuitable for use by this country, meaning England, as a weapon.

... AND WHEN YOU'RE DONE READING IT MAYBE YOU COULD COMMENT A LITTLE ON HOW THE NOTION OF NOT USING IT ON A CIVILIAN POPULATION CHANGED DURING THE WAR.

Yes. That's a very interesting subject. I mustn't be carried away too much with it...[LONG PAUSE]...So where do I start? Oh, in the...

START BY SAYING YOU SENT A MEMORANDUM TO THE APPROPRIATE AUTHORITIES...

We sent the memo... wrote a memorandum and sent it to the appropriate authorities and apart from making the technical case for believing our conclusions we also said in this memorandum that owing to the spreading of radio... radioactive substances with the wind, the bomb could probably not be used without killing large numbers of civilians. And this may make it unsuitable as a weapon for use by this country, meaning Great Britain. We pointed out however, that it was still essential to have it as a deterrent against Hitler's Germany maybe having this weapon.

LET ME ASK YOU TO DO THAT ONE AGAIN. THEN AFTER YOU READ IT JUST TALK ABOUT HOW THAT NOTION CHANGED...

In this memorandum, in addition to the technical part which gave the case for believing our conclusions we discussed the consequences. And in this we said — and I'll read this -- "Owing to the spreading of radio active substances with the wind, the bomb could probably not be used without killing large numbers of civilians. And this may make it unsuitable as a weapon for this country" — meaning Britain. Now, of course, in the course of few years, attitudes to the attack on civilians to strategic bombing had changed very much. At the beginning of the war people were very horrified by the spectacle of Rotterdam and other places where planes had bombed cities. But a few years later... the very heavy air attacks, air raids on Dresden, Hamburg and Tokyo were accepted by everybody as a necessary part of fighting a war. Without that change of attitude, I doubt whether one would have got the agreement by the American authorities to use the bomb on Japan.

... TO HAVE THIS NOTION SEPARATELY, COULD YOU SAY, "AS PART OF OUR REPORT WE SUGGESTED...ETC" AND GO ON TO TALK ABOUT HOW THE ATTITUDE CHANGED"

Now, this is therefore not reading at all. I see. OK... In our report apart from a technical part which gave the reasons for believing our conclusions we discussed the implications and including first of all that there was no defense to this weapon other than having a similar weapon as a deterrent. And we also pointed out that because of the radioactivity one could probably not use this weapon without killing a lot of civilians. And that we said would make it... might make it unsuitable for use by this country, meaning Britain. Now that was I think the general attitude — that it was wrong to, if you could avoid it, to kill a lot of civilians in war. And around that time, 1940, people certainly were still horrified by the experience for example, in Rotterdam or later the early attacks on England. But in the course of a few years, the public attitude had changed a lot. Very heavy fire raids and air raids on German cities, Dresden, Hamburg, or in Tokyo, were accepted as normal. I would doubt very much whether without that change of attitude, there would have been a decision to drop atom bombs on Hiroshima and Nagasaki.

LET'S GO NEXT TO THE MAUD COMMITTEE. WHEN THE REPORT WAS RECEIVED, YOU WERE STILL CONSIDERED ENEMY ALIENS AND THEY CERTAINLY DID NOT WANT YOU TO COME WORK ON IT EVEN THOUGH YOU WERE THE EXPERT AT THE TIME. PERHAPS YOU COULD TELL US ABOUT THAT FIRST.

All right. This report went to a committee which had been thinking about the implication of fission for war purposes. And I think in general, they accepted our conclusions as reasonable...

I'M GOING TO ASK YOU TO START AGAIN...

Our memorandum eventually reached a British government committee who were discussing the implications of the fission process. They certainly regarded our conclusions as reasonable and but... we got a message saying that from now on we would no longer work on this project problem and we would not in fact be told what was going on because we were still enemy aliens — Well, actually, I had acquired by that time British nationality. Frisch had not. But obviously it would be quite irregular to work on secret projects. However we... pointed out that the problem was very urgent and that as we had had the chance of thinking about it, we might already know the answers to some questions which had not yet even occurred to other people. And so... it was then decided to get out of the form of the official difficulties by having two layers of a committee — a technical committee of which we were members and a policy committee which in fact didn't do very much.

I'M GOING TO ASK YOU TO EXPLAIN THAT AGAIN A LITTLE MORE BRIEFLY — MAKING THE MAIN POINT THAT YOU WERE NOT ALLOWED TO WORK ON THE COMMITTEE AT FIRST BECAUSE OF YOUR ALIEN STATUS.

So... Our report went ultimately to a British government committee who were there to consider the implications of fission for the war. And who found our conclusions reasonable. But we were told we could not work on this because of we were actual of formerly enemy aliens. But this somewhat ridiculous ruling was then bypassed by setting up a bigger committee in two layers: a technical committee of which we could be members. And above it a policy committee which didn't really do much.

DIDN'T YOU FIND IT IRONIC THAT YOU WERE BEING KEPT OFF THE VERY COMMITTEE AT FIRST THAT YOU HAD BROUGHT THE SECRET TO?

Of course. But it didn't last long.

NOW COULD YOU TELL ME... THEN THAT LED TO THE MAUD COMMITTEE AND THE MAUD REPORT EVENTUALLY HAD A GREAT IMPACT ON THE RESEARCH IN THE US AS WELL. COULD YOU TELL ME ABOUT THAT?

Well this committee, the so called MAUD Committee sponsored further research on a small scale as yet in universities and came out about a year later with a report that the proposal of making a bomb seemed feasible and giving some details of what was involved in separating the uranium isotopes to the sufficient... in sufficient qualities to make some bombs. Now, that report as well as earlier discussions were... went to the United States and I believe that it made quite an impression there and... helped to accelerate the decision of in the United States, to go ahead with the full scale projects, the so called Manhattan District of the United States Army....

WHY DID IT TAKE A YEAR AFTER YOUR REPORT?

It took a year because one needed to do some more research to try... well two things. First of all, to discern that our guesses about the nuclear properties which were derived from Niels Bohr's theory were accurate and that required some nuclear physics experiments. And also one had to do some design work to see how feasible it was to build a plant that would separate the isotopes of uranium and roughly how big an effort that was. And that took time.

TELL ME AGAIN ABOUT THE MAUD COMMITTEE?

As a result of our report, the so called MAUD Committee was set up to look into many of the technical details raised by our report. And they sponsored research in universities and in some industrial firms. And a year later satisfied themselves that the project was feasible and gave some ideas of how one would go about building a plant to separate the isotopes and how much effort that would involve. Now, that report was also sent to the United States, and I believe, had a considerable influence in persuading people here to take the possibility seriously and to set up a full scale project, the so called Manhattan District Dossier... United States...Corps of Engineers.

I ALWAYS FIND IT INTRIGUING TO READ ABOUT HOW THE MAUD COMMITTEE GOT ITS NAME.

Yes. I don't think there's time for it to go into the program, but at the time the Maud Committee started... they were thinking about some name that would be innocuous enough not to give any information away. Some cover name. And about that time, a telegram had been received by one physicist in England from Niels Bohr saying that he and his family were well even though the Copenhagen had been occupied by the German army. And ending up saying inform Maud Rae Kent. Now that seemed very odd because nobody knew who this lady was, Maud Rae. But either, he assumed that... one knew her address, then you wouldn't have to say Kent. Kent is a county in England. Or if, on the other hand, one didn't know, the address, then saying Kent wasn't very helpful. So then people decided, this must be, in fact, a hidden message. It must be an anagram. And tried to concoct all kinds of anagrams on these words Maud Rae Kent, We did... Frisch and I didn't believe it and... But this was the occasion then to pick the name Maud for the name of the committee. The funny thing is that many people wrote this with periods. M., A., etc. And were convinced it was an abbreviation for Military Applications of Uranium Disintegration.

MAYBE YOU CAN TELL ME THE SHORT VERSION OF THE MAUD NAME STORY.

The name... the new committee was called the MAUD Committee and the name was in fact the name of the a former governess of professor Niels Bohr. A message concerning her had just been seen by the committee and they accepted this as a neutral cover name for the committee. However many people interpret that this as being the initials of Military Applications of Uranium Disintegration.

BUT THAT WAS NOT AT ALL THE CASE?

Nobody had thought about that.

I'M GOING TO ASK YOU NOW TO TELL ME ABOUT THE COLLABORATION BETWEEN THE UNITED STATES AND GREAT BRITAIN ON THE BOMB PROJECT. WAS IT A FAIRLY SMOOTH RELATIONSHIP?

The collaboration had a very checkered history. We started off...

(REPEAT QUESTION)

The collaboration between Britain and the United States on atomic energy had a very checkered history. We started off exchanging information on all aspects. In fact, a group of us came over in 1942 to discuss with our American colleagues what the information and the ideas we had. But then there were difficulties and it would take a long time to explain all these difficulties. And I think mistakes were made on both sides, but they resulted in complete break down of the exchange of information on this subject. Until 1943 when Roosevelt and Churchill at the Quebec meeting agreed to limited exchange of information. Limited to those areas in which there were activity both in Britain and in the United States. And eventually, as a result of that, many of us were moved over to assist in the American project because it was clear that it was not sensible to try and operate a large... construct a large scale plant in Britain during war time.

DID YOU AND SOME OF THE OTHER SCIENTISTS FEEL THAT THIS OFF AND ON LACK OF COOPERATION ON THE DIPLOMATIC LEVEL WAS UNNECESSARY OR GOT IN THE WAY OF PROGRESS?

Well we... All the scientists working on the project in England were of course... they felt very frustrated particularly as it was impossible to get a decision. You see if obviously a joined effort would be the most efficient and economic. But if that wasn't possible then one should seriously consider carrying with such a project in Britain But that was very difficult in wartime. And so, so it wasn't easy to take that decision. Meanwhile we were working on the old research and planning, but we didn't really know where this was going.

LET ME ASK YOU TO SAY THAT AGAIN AND APPROACH IT BY SAYING,“WE SCIENTISTS IN BRITAIN DIDN'T KNOW THAT THERE WAS GOING TO BE...?

During that period when there was uncertainty about exchange of information of collaboration we scientists in Britain working on this project felt very frustrated because we didn't know whether there would ultimately be a joint plant in the United States or whether we would possibly go for a separate plant in Britain in spite of the very great difficulties of war time.

TRYING TO ACCOMPLISH SUCH A THING IN BRITAIN WITH AIR RAIDS AND EVERYTHING ELSE WOULD HAVE BEEN NEARLY IMPOSSIBLE.

Certainly in... to achieve such a project during war time in Britain would have been extremely difficult. I think it would not have been impossible, but would have meant using scarce material, scarce labor and so on and therefore interfering with other important war time activities.

AND SO YOU HOPED THAT THERE WOULD BE SOME COLLABORATION WITH THE UNITED STATES?

We hoped that the problem would be sorted out and we would collaborate with the United States or at least that there would be a decision one way or the other.

YOU WERE ALWAYS CONCERNED ABOUT THE GERMANS --WHETHER THEY WERE DEVELOPING AN ATOMIC BOMB. I UNDERSTAND THAT YOU PERSONALLY GOT INVOLVED IN TRYING TO FIND OUT HOW THEIR RESEARCH WAS PROGRESSING. COULD YOU TELL US ABOUT THAT?

Yes. Obviously at that time, everybody was worrying whether the Germans were working on the atomic bomb also and how far they had got. Of course, the intelligence people were making great efforts to find that out. But I decided one could find out a certain amount without intelligence organization by looking at the German scientific journals which were becoming available because from the published lecture lists and other details, you could get an impression that most of the German scien... physicists were in their normal positions doing their normal work. And if anybody was working on atomic energy, it was very few people. So we decided that very probably there was some interest in... the subject, but not a crash program. But we didn't rely on that conclusion. It was too important a matter to act on impressions, but on the whole it later turned out to be that was more or less right.

WHEN DID IT BECOME CLEAR THAT THE GERMANS WERE NOT GOING TO HAVE AN ATOMIC WEAPON DURING THE WAR AND THEN MAYBE YOU CAN GO INTO TALKING ABOUT HOW THAT AFFECTED THE PROJECT AT LOS ALAMOS. WAS THERE ANY THOUGHT OF ABANDONING THE PROJECT AT THAT POINT?

When finally Germany was defeated in early 1945 it was of course clear that they did not have an atom bomb. In fact it came out they were not at all close to it. And in that sense one of the reasons for developing the weapon on our side had gone. In Los Alamos, nevertheless we decided to... or we continued working on this project. By now this was felt it was the weapon or more and it was important for the allies to have it at their disposal. It was not for us to say what should be done with it. The... Many of the scientists in fact, trying to urge the government not to use this at least on cities and at least not without previous warning by demonstrating this bomb The interesting fact is that this was more people were concerned with that in Chicago who had been working on... not working on the weapon itself than in Los Alamos. And probably the reason was that people in Los Alamos were still very busy and didn't have too much time to think about general principles, where as the Chicago people had essentially finished their work for the... for the project. And that's at least one reason why they wrote a memorandum urging the government not to use a bomb without previous steps. That is probably too long.

YOU WITNESSED A TEST AT THE TRINITY SITE. COULD YOU DESCRIBE IT? HOW DID IT AFFECT YOU TO SEE THE RESULTS OF YOUR CALCULATIONS SEVERAL YEARS PREVIOUS?

Yes. Well I... was present at the first test in Alamogordo... the so-called Trinity Test. And it was a tremendous experience. They... of course, we knew what to expect. Thought we knew what to expect. But to see it in reality is still a very different matter. To witness this enormous flash of light and to see the cloud rising above the site it... It was an awe-inspiring experience. And the reaction was a mixed one. On the one hand awe and really feel of the enormous new powers unleashed. At the same time, of course, gratification that we had been right and that the work done by so many people had been successful.

HOW DID YOU PERSONALLY FEEL ABOUT THE MILITARY USE WITHOUT WARNING?

I felt that we could not as scientists have a very firm view on this because we didn't have enough information about the strategic situation. But what we felt was important was to... As scientists we could not have very firm views, I felt, about the use of the bomb or not to use it because we didn't know enough about the strategic situation, the requirements. But, I regarded this as very important that one should explain to the authorities who were not scientists all the implications of this new weapon which we had... time to think, about. And we knew that people like Robert Oppenheimer and Enrico Fermi and others were in touch with the authorities. They were very articulate people and we could rely on them to get these important points across. We also believed that the people in authority were people of good will who would take responsible decisions once the implications were explained to them. In my hindsight I would say we were perhaps a little naive and a little bit optimistic in this respect. But I certainly did not expect that these bombs would be dropped without previous demonstrations. I would have thought the ideal solution would have been to drop the bomb on a relatively uninhabited area without warning. This would involve doing some destruction and killing some people. But this was wartime after all. Because without this people wouldn't have appreciated what this bomb was capable of.

HOW DID YOU ACTUALLY HEAR THE NEWS THAT THE BOMB WAS DROPPED ON HIROSHIMA AND HOW DID YOU REACT TO THAT?

I do not recall just how the news came to us. Whether we heard it on the radio or whether somebody told us who had heard it. Again, the impression was mixed because it meant, of course, that the war was over or practically over. And it meant that our work had helped to bring that about. We were gratified by this. But this was of course mixed with a feeling of horror about the casualties and the suffering that was caused. Of course, human imagination is limited and the full impact of how what is looked like became very much stronger later when one could see the pictures and hear detailed reports of what... how it actually felt.

WE HEARD THAT OTTO HAHN IN INTERNMENT IN ENGLAND HAD BECOME VERY DEPRESSED UPON HEARING THE NEWS AND HIS ASSOCIATES THOUGHT THAT HE WAS PERHAPS EVEN SUICIDAL... DID YOU OR ANYONE YOU KNOW HAVE THAT KIND OF REACTION?

Uh...

WERE YOU MORE PHILOSOPHICAL ABOUT THE NECESSITIES OF WAR?

Well, you see reactions were influenced by the fact that air raids and killing of civilians were by this time commonplace. The, in fact the number of people killed and injured in Hiroshima, for example, was no greater, about the same as a typical fire raid on Tokyo. So it was not the scale of the casualties that made a difference. What made the difference was the ease with which it was done. Instead of enormous operation involving hundreds of planes and so... and here was one plane and one pilot who pressed the... pressed the button to release this bomb... That has... that makes a tremendous difference in the situation. But in the actual effects, it wasn't so different. So just as we were used to raids on Japanese and German cities, this was another one. But this was one which had helped to finish the war and therefore... I think the basic reaction was still to welcome it. Although one might have wished that it would have been done in another way.

I'D LIKE TO ASK YOU JUST A COUPLE OF QUESTIONS ABOUT KLAUS FUCHS? WAS IT FAIRLY WELL KNOWN AMONG SCIENTISTS WHAT THE EFFECTS OF THE RADIATION AND FALLOUT WERE GOING TO BE? WE HEARD PEOPLE ON THE STRATEGIC BOMBING SURVEY MARCHING INTO HIROSHIMA AND NAGASAKI NOT REALLY AWARE OF WHAT PROBLEMS MIGHT BE THERE WITH RADIOACTIVITY. WAS THAT THE CASE OR WAS IT FAIRLY WELL…?

Well, the dangers of radiation were of course well known. So the actual limits of what amounts of radiation were...could be tolerated safely by people without ill effects were not too well known and in fact, one was a lot more optimistic in those days and came later on the tolerance levels were reduced very much in the course of time. But the problem of what one didn't know really, was how much radiation there would be after the event. We knew quite well what radiation would be produced in the explosion itself. But how much radioactivity would remain is a very complicated question. The Hiroshima and Nagasaki bomb were in fact exploded in the air at a reasonable altitude that increases the blast effects. And that means that most of the radioactivity is carried up to great heights by the mushroom cloud. And is harmless. Now, how much of that will eventually come down, or how much of that reached the ground immediately is a very complicated question. Nobody knew that.

LET ME ASK YOU ABOUT THE RADIATION QUESTION AGAIN IN A LITTLE DIFFERENT WAY. WAS IT AT ALL SURPRISING TO YOU, TO THE PHYSICISTS THAT PEOPLE IN HIROSHIMA AND NAGASAKI WERE SUFFERING FROM RADIATION POISONING LONG AFTER THE TIME OF THE BOMB?

It... it was not in itself surprising that there should be radiation effects from the people exposed at the time of the explosion. The and of course, if the dose of exposures is limited then the ill effects may take a long time to develop. Now there has been a lot of controversy and a lot of controversy about how much persistent radioactivity was left in, for example, in Hiroshima. And that is very hard to predict how much of the radio active stuff will actually get down into the ground. But we were told by the experts at first that there was none. And then later, this was modified a little bit. So that caused some surprise.

THAT THERE WAS NO APPREHENSION ON THE PART OF THE MEMBERS OF THE STRATEGIC BOMBING SURVEY GOING INTO HIROSHIMA AND NAGASAKI AND FEARING FOR THEIR OWN HEALTH.

I think probably they didn't know enough to be frightened.

LET ME ASK YOU TO START OVER...

Of course the people of the military survey who went into... to find out what happened probably did not know enough about the problem to be frightened. But in fact, I believe, the amount of radioactivity present after the explosion was not enough to hurt anybody who came there for a short time.

NOW TELL ME A LITTLE BIT ABOUT KLAUS FUCHS. HOW DID HE FIRST GET INVOLVED WITH THE BOMB PROJECT?

Klaus Fuchs joined us in 1941. We were very short handed and I needed a collaborator with whom I could discuss the theoretical problems and who would help. Most theoretical physicists were already busy with other war work. I knew that Fuchs, who was also a German - a so-called enemy alien - was not then doing any war work and so I invited him to join us. And there was some difficulty about getting permission to employ him. It were of course... was at first told I should tell him only what was immediately necessary but not the full story, But I said I... that would make him useless for me. And I either told him everything I knew or nothing or I couldn't employ him. Then I was told to go ahead.

SO DID YOU HAVE ANY IDEA ABOUT HIS COMMUNIST LEANINGS OR WAS THERE ANY REASON...

No. At the time I had no suspicion that he was a communist or that he might be disloyal to the...

I'M GOING TO ASK YOU TO START AGAIN...

At the time when I took on Fuchs to help me, I had of course no idea that he was actually a communist. I did know that in Nazi Germany he had worked with the socialist students who were in fact communists. But that was understandable because they were the only ones fighting the Nazis. And later on it never then was clear from conversation that he had extreme views. He never said very much, but he managed to give the impression that his views were more or less the same as ours.

SO WERE YOU VERY SURPRISED WHEN YOU GOT THE PHONE CALL IN 1950 THAT HE HAD BEEN ARRESTED AND CHARGED WITH SPYING?

When I heard about his arrest, of course I was completely surprised and at first disinclined to believe it. I mean not that he was arrested, but that he had been a spy. We thought there could have been some misunderstandings or what not. Of course we didn't know exactly what he was charged with. And in fact as the newspaper report said that he didn't have a lawyer to act for him, I went immediately to London to try and see him and make sure that there was a lawyer. And in fact, by that time, he had... he had found one. But in that conversation he convinced me that indeed this was... this charge was correct.

DID IT MAKE ANY DIFFERENCE REALLY TO THE RUSSIAN BOMB EFFORT OR WERE THERE REALLY SECRETS SOLD...

Well there were technical details which you can't find out until you actually have made a plant. And it's certainly must have been some help to the Soviet authorities to get that information from Fuchs and presumably from others. I have asked several Russian colleagues how they — to estimate how much time the information from Fuchs saved them. And the estimates varies between one and two years. Which is therefore a substantial help if you like. But of course, in the long run, it didn't make any difference.

IN CLOSING, IS THERE ANYTHING THAT HAS HAPPENED OR NOT HAPPENED IN THE LAST 40 YEARS IN THIS NUCLEAR AGE THAT SURPRISES YOU?

Well in the 40 years or so of the atomic age there have of course been many developments which were not foreseen. We didn't--I personally didn't think of the hydrogen bomb as a very likely weapon to be developed. But the most surprising, the most unexpected thing to me, is the present arms race which seems completely incomprehensible. Because everybody knows that nuclear weapons are not weapons to fight wars. But are good only for... as a deterrent against other people using such weapons. Once you accept that, it's clear that a very limited amount of weapons is sufficient to have an effective deterrent. And to have twice as much or ten times as much doesn't make you any more secure. And therefore I can... I find it completely incomprehensible why the governments of both side... I mean both the Soviet Union and the United States — are so worried about the bombs.

ARE YOU SURPRISED THAT NUCLEAR WEAPONS HAVE NOT BEEN USED IN WARS SINCE 1945?

No. I don't find that surprising...

(REPEAT QUESTION)

I do not find it surprising that nuclear weapons haven't been used because everybody is afraid of the consequences. In fact, many people claim, and I think with some reason, that the fact that we haven't had a war for the last 40 years is largely due to the presence of atomic bombs. I mean that we haven't had a world war in that time was due to the existence of atom bombs which make everybody frightened.

(REPEATS QUESTION)

I do not find it surprising that nuclear weapons have not been used again because everybody is frightened of them and of the consequences of using them. The in fact many people attribute the fact that we have not had a world wide war in the last 40 years to the existence of atom bombs.