ONE MAN AND HIS BOMB

FIFTY YEARS ago next Sunday, in the desert of southern New Mexico, the sun rose twice. The second burst of light on the horizon ushered in a hot, thundery day like any other at the time of year. The first had ushered in the age of nuclear weapons.

Hiroshima was not the first atomic explosion, for the Americans had already tested their bomb, and Rudolf Peierls had been there to witness it. A physicist at the secret atomic laboratory at Los Alamos, New Mexico, he waited with colleagues on a hill 20 miles from "point zero" through the long night while the weapon was prepared. As the final phase of the countdown began, he lay on the ground and then, a little before dawn, through a piece of thick dark glass, he watched what happens when plutonium atoms burst.

"We were struck with awe," he wrote later. "We had known what to expect, but no amount of imagination could have given us a taste of the real thing." Peierls had reason to feel a special awe, for it was to him that, five years earlier, the revelation had come that atomic weapons were possible.

Now aged 88, he lives in a retirement home near Oxford. You turn off the road into what was once a private country estate. Up the hill, among the trees, is the home, with a smart new wing overlooking a lawn and the car park below.

Ask for Sir Rudolf and the young nurse shows you the way. "Rudi," she says after knocking, "your visitor." His room is L-shaped, compact, with a bed, a bay window, a desk and plenty of papers. He is sitting in the window with a magnifying glass and a notepad covered in spidery algebra.

He is a small man with thick, whitening hair and a face that is slightly twisted, perhaps by his years of pipe-smoking or the struggle with poor eyesight. Though he settled in Britain more than 60 years ago, his accent and occasionally his grammar are unmistakably German.

If you knew only that he was one of the creators of the atomic bomb, you might be tempted to think you were in the presence of some domestic Strangelove, grown frail in old age. Nothing could be further from the truth. Sir Rudolf Peierls is humane, gentle and thoughtful. He is precise in conversation, choosing his words with fastidious care, slow to generalise and even slower to criticise anyone personally. He is generous and scrupulous. Although he has no religion, and although the paradox may seem improbable, this little old man possesses a certain saintliness.

HIS SPECIAL relationship with the atomic bomb was born at Birmingham University one spring morning in 1940, when Otto Frisch, an Austrian colleague and fellow refugee from Nazism, asked him a question. They knew that ordinary uranium could not be made to explode, Frisch said, but what about the rare strain of uranium known as U-235? If you could refine enough of it, could it be made into a bomb? Peierls himself had already developed the formulae needed to answer just such a question. So he and Frisch performed the calculations and the answers revealed that an atomic bomb, until that moment dismissed by all the best minds as impossible, could be made, and made within a few years.

What do you do, when you have in your hands such appalling knowledge? Do you lock it away and hope no one else notices? Peierls and Frisch did not. Instead they committed their discovery to paper - the first theoretical blueprint ever written for a "super-bomb", as they called it - and ensured that this was passed to the British government.

The blast from the super-bomb, they ex-plained in a covering letter, would be sufficient to destroy all life throughout the centre of a big city. No material or structure could be expected to withstand it. In addition, the bomb would spread deadly radioactivity over a large area, a characteristic which would reduce its usefulness as a battlefield weapon.

In a sentence that is rich in significance, they wrote: "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." But, they added, it was "quite conceivable" that Germany was already developing such a weapon.

Before long, a full-scale feasibility study was underway which led to the creation of a British atomic bomb programme. After the United States had entered the war, it was recognised that only the Americans had the resources to make the bomb. The "Manhattan Project" was born, and Frisch and Peierls went to the US to join it, Peierls eventually becoming head of the team of British scientists at Los Alamos.

He was a member of the innermost councils, working closely with two giants of physics, Hans Bethe, later a Nobel Prize winner, and J. Robert Oppenheimer, the laboratory director. When the bomb was tested on New Mexico's Jornada del Muerto - the Dead Man's Trail - he was there to see the man-made sunrise. To this day his name is on certain patents associated with the bomb mechanism, although they are worthless (no country making atom bombs observes the niceties of patent law). Rudolf Peierls not only provided the inspiration; he was among the handful of men most intimately involved with creating the atomic bomb.

WE KNOW what happened. Half the population of Hiroshima and half the population of Nagasaki were killed, some of them more or less instantly by blast or heat, and as many again by radiation over months and years. Just two bombs, and more than 300,000 dead. The Cold War followed, and an arms race that led from atomic weapons to hydrogen bombs that were 1,000 times more powerful, to intercontinental missiles and to Mutual Assured Destruction. Even today, at the touch of a few buttons, mankind could be destroyed.

Half a century on, you wonder: how does anyone live with such a thing? Peierls has clearly managed to do so. He has led a happy and fruitful existence in Britain, first at Birmingham and then at Oxford, where he was Wykeham Professor of Physics from 1963-74. He has taught thousands of grateful students, published widely both for the scientific and the general reader, become a Fellow of the Royal Society, a CBE and a knight. He is not a monster, and nor is he tormented by guilt; he has a view of his past which is both simple and firm, and it does not require him to lose sleep.

He identifies two moments at which he made important moral choices. The first was when he and Frisch decided to alert the British government to their discovery. The reasoning was straightforward, as he says now: "We knew that the Germans had good physicists and our main incentive in urging rapid action was the fear that the Germans would get there first." It was a conclusion that Peierls was well qualified to draw. He was a Berliner by birth and upbringing, and he had also studied during the 1920s with some of Germany's finest scientists. Not only would it have been foolhardy to assume that these men had missed what the two refugees had spotted, it would have been irresponsible. "The thought of this weapon exclusively in Hitler's hands was a nightmare."

The other important moment for Peierls came when the fear that the Germans were developing the bomb was demonstrated to be unfounded. This was only established with certainty as the Third Reich collapsed, but Peierls satisfied himself that there was no threat in mid-1944, through a study of some current German academic publications which came his way. These showed that those scientists who would have been essential for any German atomic weapon project were still at their universities, lecturing more or less as usual. This meant that the original rationale for developing the bomb was gone; Germany was not making a nuclear weapon and was all but beaten. There was, moreover, no possibility that the Japanese might have a serious atomic bomb programme.

Why not quit then? One scientist in the British team, Joseph Rotblat, did so, leaving Los Alamos on grounds of conscience, but Peierls and the rest worked on. "So far as I can reconstruct the situation," he says, "first of all there was still a bloody war going on, and here was a weapon that would obviously end it. It should of course be used in a humane and sensible way, and we felt, or I felt, that we trusted our government to be responsible enough to think about this. We felt that provided the American authorities were made aware of the implications, one could trust them to use it in a reasonable way." In this he was disappointed. He expected that the power of the bomb would be demonstrated to the Japanese before it was used in anger, perhaps by dropping it over some remote area of Japan, or by inviting observers to a test. This was, he admits, a naive view. The US government always intended to drop the bomb on a city, and the scientists had no power to prevent that.

Bird of Passage, Peierls's autobiography which was published in 1985, contains just six lines on Hiroshima and Nagasaki, referring to the elation with which Los Alamos greeted this news that meant the war must soon end, and expressing sorrow at the suffering the bombs must have caused. When he elaborates, he says that he will not dismiss the use of the atom bomb as immoral (although he believes the attack on Nagasaki was "unnecessary and irresponsible"). Instead, he deploys an arresting argument. "One has to remember that the bombs that were used on Japan fitted into the pattern of warfare at the time. The number of casualties in Hiroshima was no greater than in the fire raids of Tokyo, or Dresden, or Ham-burg. The interesting thing is how public attitudes changed. In the beginning, when you had the air raids on Guernica and later Rotterdam, everybody was indignant. This was not a civilised way of behaving. A few years later, after Dresden, nobody turned a hair. If it were not for that change of attitude, it might have been harder to drop the bombs on Japan."

In other words, if the scientists shifted their moral ground, they did so in step with the rest of the world. The responsibility for the bombing of Hiroshima, he implies, is shared with the mass of people who supported the firebombing raids and who welcomed with relief the news of the devastating new weapon.

All of this Peierls spells out slowly, thoughtfully, looking down at the floor or into the middle distance as he searches for the right words. His language is studiously unemotional; only once does he lapse into something like rhetoric, when he remarks: "As regards the casualties, I don't know whether I would rather be blown up by an atom bomb or perish in a fire raid."

The window bay is warm and bathed in bright sunlight, and we sip coffee as we talk. He came to this home after the death a few years ago of his wife Genia, a Russian-born physicist whom he met at a conference in Odessa in 1930. His eyesight is now so poor that he asks me to add milk to my coffee myself since he does not trust himself to pour. This explains the magnifying- glass by his hand and the scanning machine on his desk, which enlarges type for him. His eyes are not his only problem; he also has regular dialysis treatment in Oxford. As a result, he can no longer keep pace with the academic literature in his field but - he taps his page of calculations - "I'm looking at some old problems which have loose ends to them."

The arguments he has just elaborated - about the need to start making the bomb in case the Germans were doing it too, the need to complete it because it could end the war, the change in attitudes to the mass killing of civilians - add up to a framework of thought with which Peierls is comfortable. Not, perhaps, completely comfortable ("I do think about it, of course," he says), but sufficiently so. In this matter he is a study in certainty and consistency. I discussed these matters with him and I have read his writings on the bomb as far back as 1946. There have been few discernible shifts; indeed, for all his careful choice of words today, the language then and now is remarkably similar. Partly, it is that he is often asked these questions and so, like a politician, he has learnt the answers. And, of course, he is a scientist; the untidiness of his offices may be notorious, but in his mind there is order. There is also something innate, a fixity of mind, a steady emotional state which gives him confidence in his own thought. Oppenheimer believed - in a famous phrase - that the bomb-makers had "known sin". Peierls disagrees. "I don't think I have. Of course, nobody enjoys being associated with a horrible weapon like that, but I still have a feeling that what we did was right in the circumstances."

IT HAS been written that the men who made the atom bomb drew a line across history beyond which nothing was the same. Peierls recognised that immediately in 1945, and from then until now he has been involved in attempts (these would not be his words) to limit the damage. Even before leaving Los Alamos he wrote to Clement Attlee, by then prime minister, pressing him to urge caution on the Americans ("a naive gesture; I don't suppose he ever saw it"). On his return to Britain he helped establish the Atomic Scientists' Association, campaigning to increase public and official understanding of nuclear matters. Its members lobbied ministers, published pamphlets, held meetings and even ran a mobile exhibition, the "Atom Train", which toured the country in 1947-48.

A flavour of this missionary work may be had from the Atom Train guide, which concluded: "All industrial nations will want to set up plants for atomic power. The same plants produce materials from which to make atom bombs, if it is desired to misuse them for destruction. If atomic energy is not so misused, it holds promises of great advances in medicine, in industry, in the supply of power, and as a result in our standard of living. Which is it to be?"

He has, too, been active in Pugwash, an international scientific group dedicated to halting the arms race (it takes its name from the Nova Scotian town where it held its first conference in 1957. This is one field in which he will use what is for him strong language. "The arms race was justified by the feeling that you have to have more weapons than the potential enemy. That of course is nonsense. It doesn't take that many bombs to cause unacceptable damage. That's the only purpose - deterrence. These vast numbers are completely crazy."

When I talked to him back in the Reagan days of 1985, I asked what he thought of Star Wars and elicited a similar flood of contempt. "I am totally opposed to it... fortunately I do not believe that the thing can possibly work. I believe it can not even come so close to working that the Russians might expect it to work, so the main drawback is the enormous expenditure of talent and manpower and money that goes into it." These arguments have something in common. Much modern discussion of nuclear weapons tends to be moral, but Peierls deals in a different currency: the arms race is logically faulty because it leads to too many bombs; Star Wars is a waste.

A decade ago, he regarded the notion that the world might ever again live without nuclear weapons as so Utopian it was only worth discussing to dismiss it. Now, with the fall of the Wall and the change in superpower relations, "I have come closer to accepting that as a possibility." If it ever becomes more than a possibility, he has an intriguing proposal. "Whistleblowers are important - people who are prepared to stand up and complain when their own country is making atomic weapons." By this he means scientists or officials who know that their government is secretly producing bombs. "As part of the agreement of a non-nuclear world, there should be an obligation that the laws of each country should contain protections for the whistle-blowers." Of course, says Peierls, some countries would not comply, so it is important that others should be bound to protect, say, an Iraqi who blew the whistle on his government. With such protection, for example, Mordechai Vanunu, the technician who made public details of the Israeli nuclear programme, might not now be in jail in Israel.

His opinions have on occasion landed him in trouble - and his associations, for he was a close friend of the atom spy Klaus Fuchs, although he was as astonished as anyone when Fuchs's treachery was revealed. In the McCarthy years, Peierls was effectively blacklisted in the United States. Once, he waited eight months for a visa to attend a conference in Chicago, and when it arrived it was too late to go. Later, his contract as a consultant to the British Atomic Energy Research Establishment was terminated because, he believes, the US authorities did not want him to see classified papers there.

Today, from his cosy room in Oxfordshire, Peierls takes little part in public affairs. Instead, progressively, he has become a historical resource. The past dozen years have seen the release of a flood of official documents on the origins of the nuclear age in the US, Britain, the Soviet Union and Germany, and in consequence the study of the field has become more meaningful and more fashionable.

An anecdote will help explain why Peierls has an important role to play in this. During the Manhattan Project, when he headed the British team at Los Alamos, he used to write regular reports on activities in the laboratory for the British mission in Washington. These, he knew, were a cause of suspicion among the Amer-icans, who feared leaks, and when he was approached by a senior American about the reports, he expected to be asked to cease the correspondence. Instead, the US authorities in Washington wanted copies for themselves, for they had found to their annoyance that, thanks to Peierls's shrewd summaries, the British were often better informed than they.

Peierls still has that clarity of vision and combines with it an impressive memory for people and events. If you misquote someone, he spots it; if a date is wrong, he will usually put you right. Since he is among the two or three most senior surivors of wartime Los Alamos, his views are constantly sought; his name appears widely in acknowledgements and footnotes; he is still asked to review in the New York Review of Books and elsewhere; and he corresponds with historians everywhere. And always with the same care, the same anxiety not to be wrong. Once, after a conversation, he wrote me a hasty letter of correction relating to some minor point in our discussion: "I have since found after discussion with some colleagues..."

With good reason, Peierls wants the record straight, for his has been an astonishing life, straddling that line across history. Nobody alive today under the age of 65 can have any memory of the world on the far side of the line, the world as Peierls knew it when he made his contribution to the bomb. And yet we on this side of the line are quick to judge the bomb-makers. Over the next few weeks, as we mark the anniversaries of the New Mexico test, Hiroshima and Nagasaki, we will be tempted into horror and disbelief that men could have made such a machine of destruction.

Rudolf Peierls is proof that the men who did so were not monsters or fools. Most of them are dead, and he is a kind of spokesman: they were generally honest, thoughtful men who willingly applied their remarkable talents to the war effort in the manner that their governments requested. If there is guilt, it falls much more widely than on the men of Los Alamos. !