J D Bernal

by Andrew Brown

  By the time of the next large WPC meeting in Berlin in the summer of 1952, Bernal was disappointed that popular demand had not been more successful in forcing the issue of nuclear disarmament at the UN. This failure, in his opinion, was largely due to the US policy of accelerated rearmament, in pursuit of ‘a new Holy War against communism to liberate Europe, restore Chiang Kai Chek and open the door to American enterprise’.84 Still Bernal reaffirmed in his speech a belief in ‘a policy of comprehensive, fair, practicable and rapid disarmament which involved quantitatively the substantial reduction by one third to one half of all armed forces, armaments and armament industry; qualitatively, the entire prohibition of weapons of mass destruction, including all forms of atomic and bacteriological warfare.’ To achieve these ambitious ends, a system of inspection and control that would supply ample security to participating countries needed to be in place within a year. There were signs that Bernal was moving closer to the type of pragmatic approach espoused by Blackett; he told the audience that he had ‘made the mistake of being too academic about disarmament in the past. It should be presented as a practical solution to particular problems such as the Korean War.’

  In 1952, there was another, more personal, international appeal that captured the support of many left-wing activists: the campaign to free Julius and Ethel Rosenberg, who had been found guilty of espionage in the US in April 1951. The judge, when handing down their death sentences, held them responsible for ‘the Communist aggression in Korea’ because their treachery had put ‘into the hands of the Russians the A-bomb, years before our best scientists predicted Russia would perfect the bomb’.85 Portrayed as ‘the first victims of American fascism’, the pair maintained their innocence and hoped that public outcry might save them. Julius wrote to Ethel in March 1952: ‘We must soberly realize that our only hope rests with the people.’86 They wrote letters from Sing Sing to their supporters, claiming to speak for peace; these messages were amplified in Europe by the Cominform, determined to maximize anti-American sentiment.

  Julius Rosenberg was identified as the central figure of a wartime Soviet spy ring, codename Enormoz, by cryptographers working on Venona material. These intercepted signals were too valuable and secret to use at the Rosenbergs’ trial. Instead Julius’ role in transmitting atomic secrets to the Soviets was mainly established by the evidence of Ethel’s brother, David Greenglass and his wife Ruth. Ethel was convicted solely on their testimony. From August 1944, David Greenglass had worked as a machinist at Los Alamos, fabricating the high-explosive lenses that were so crucial in the implosion design of the plutonium bomb. He described this process and other details of the bomb design to his brother-in-law at the end of the war.

  Sage evidently wrote to the Friends of the Rosenbergs Committee in early October 1952, and received an excited response, saying that his was the first letter they had received ‘from a scientist abroad’ and gave them ‘a real lift’.87 This was followed two days later by a letter from the Rosenbergs’ attorney asking him to review the case against them, particularly the evidence of David Greenglass. Bernal’s view was that the information that Greenglass might have passed to Julius Rosenberg was of ‘a very low order’ and did not constitute ‘the secret of the atom bomb’.88 He suggested that the principle of convergent implosion or hollow charge had been known for 60 years, and it would be the first method to be explored ‘by any intelligent designer if faced by the problem of rapidly compressing a volume of material’.89 Sage subsequently spoke at a public rally in London to save the Rosenbergs – a contribution again noted by the FBI. Another speaker was Dennis Pritt, a communist, King’s Counsel, MP for Hammersmith and leading member of the British Peace Committee. He subsequently helped Bernal to file an affidavit with the American court. In the affidavit, Bernal gave his academic credentials and pointed out his expertise in high explosives as a result of his war work. In an attempt to minimize the impact caused by Greenglass’s evidence, Bernal stated that: ‘The principle of the converging shock wave is not a new one. It has been utilized in practice as far back as 1792. It was rediscovered by Admiral Munroe of the US Navy in 1888, it is known as the Munroe effect and was widely publicized at that time and later…’ There were, he said, British patents dating from 1911, and the shaped charge was the principal mechanism of the tank-destroying bazooka.

  Whether Bernal’s evidence was ever considered in the Rosenbergs’ appeal is not clear, but it did not help them. The Supreme Court refused to order a retrial, which prompted Bernal to write a long letter to Einstein, railing against the injustice of their case and asking him to use whatever influence he had on their behalf. The Rosenbergs had become emblems of the Cold War. Their deaths in the electric chair pleased Stalin’s regime because they were innocent victims of American fascism in the eyes of millions, and, by the same token, the executions served to demonstrate the resolve of the new Eisenhower administration against communism.

  What might have puzzled Stalin was that the Rosenbergs were executed without confessing their guilt: such loose ends would never be permitted under his rule. From 1948 onwards, he had become increasingly concerned that Jews in the Soviet Union represented an internal threat to his iron grip on the state. He embarked on a secret pogrom and in August 1952, after interminable torture and a closed trial, the members of the Jewish Antifascist Committee were shot. They were guilty of bourgeois nationalism and of being used as the tools of American intelligence to undermine the Soviet system. Their families, exiled in Siberia and Kazakhstan, were only informed of the executions three years later. At the meeting of the Presidium of the Central Committee in December 1952, Stalin proclaimed that ‘every Jew is a potential spy for the United States’.90 The fate of the Jewish Antifascist Committee was intended to be but a grisly prelude to the systematic persecution and deportation of Soviet Jewry. A glimpse of this was seen in the West when, in January 1953, news of the Doctors Plot was announced from Moscow. This implicated many leading physicians, mostly Jewish, in a conspiracy to kill Soviet leaders on the instructions of American, British and Zionist intelligence agencies. Stalin had orchestrated the campaign, and was frustrated with the time it took his security forces to extract the necessary confessions. Accusing the KGB of working ‘like waiters in white gloves’ he ordered the chief investigator to ‘beat them, beat them, beat them with death blows’.91 When Stalin died in March, the surviving doctors were released and Pravda even reported the fact. At the time, Churchill wrote to Eisenhower that ‘nothing impressed me so much as the doctor story’ which he thought must have ‘cut very deeply into communist discipline and structure’.92

  The doctor story and the narrowly averted pogrom caused little comment in the West, and not all the comment was sympathetic – physicians in France, for example, saw fit to denounce their Soviet colleagues.93 The Rosenberg case, by contrast, had become an international cause célèbre. The indignation about the Rosenbergs’ conviction and subsequent execution stemmed from a feeling that their trial was unfair and that they had been denied their individual rights. But such individual rights had no meaning in the USSR (nor for that matter in Mao Zedong’s China), where they were subsumed by the state. It was precisely this lack of individual rights that made the massive Stockholm Appeal doubly meaningless. By the time of the Warsaw Congress, according to Montagu,94 the total number of signatures gathered had reached 473,154,259. Of these, nearly three quarters were either from China or the USSR – states where there was no such thing as free opinion and where, in any event, the rulers were indifferent to the desires of the people. The number of British signatures was 1,343,340, which was less than ten per cent of those collected in France. Bernal was disappointed that the British had been ‘the slowest to answer the call of Stockholm’.95 He was right that ‘this is little indication of the spirit of our people’ who desired peace and the avoidance of nuclear war as fervently as any other nation. What Sage could not see was that the British public were rightly suspicious of the motives behind the Stockholm Appeal and
were exercising innate caution.

  As part of the celebrations for Stalin’s seventieth birthday in December 1949, it was decided to establish a committee to award an annual Stalin Peace Prize. The winners would receive a gold medal and 100,000 roubles. Bernal was a committee member, and in 1951 the first prize was given to Joliot-Curie. In 1952, Sage nominated his old colleague from the Royal Institution, Kathleen Lonsdale, who was a Quaker and a pacifist – she did not win. On 21st December 1953, Bernal was one of ten winners. His photograph was on the front page of Pravda and he was accurately described as ‘a progressive scientist who wants the achievements of science to serve human progress and peace’.96

  17

  The Physical Basis of Life

  Even in the darkest days of World War Two, the BBC adhered to Lord Reith’s maxim of informing, educating and entertaining the public. In March 1942, as part of a series ‘Science lifts the veil’, Sir William Bragg interviewed Sage about ‘The problem of the origin of life’. It had been Bragg who arranged for Bernal to give a series of lectures on ‘The molecular architecture of biological systems’ at the Royal Institution in 1938, and the broadcast was to some extent a summary of those talks. Bernal again referred to the gap between the molecular world studied by biochemists and the larger objects that could be seen under the microscope – the gap in which most structures important for life exist. In addition to the ultracentrifuge and X-ray diffraction, there was by 1942 a new tool for exploring the gap: the electron microscope. Bernal explained how the Tobacco Mosaic Virus (TMV) that he studied by X-ray diffraction had now been visualized directly by electron microscopy (he tactfully omitted to mention that this work took place in Berlin).

  Bragg asked Bernal whether viruses are alive or not. Chuckling, Bernal replied he would rather not say ‘because my colleague Dr Pirie, who has done so much of this work on viruses and has written a cutting essay on the meaninglessness of the term “life” would never let me hear the end of it’.1 What the acerbic Pirie wrote was:

  We have now examined destructively the various qualities which might be used to define the word ‘life’ and we have found that they are individually inadequate for even an approximate definition… combinations of two or three qualities, though they might be drawn up to exclude all obviously non-living systems, will also exclude some which are, if not typically living, at least generally included in that category.

  Until a valid definition has been framed it seems prudent to avoid the use of the word ‘life’ in any discussion about border-line systems and to refrain from saying that certain observations on a system have proved that it is or is not ‘alive’.2

  Instead of offering Bragg a definition, Bernal preferred to quote Engels, one of his favourite philosophers of science, as saying that ‘Life is the mode of action of proteins’ – which had become the credo for his own research programme.

  Beginning in 1929, Astbury in Leeds had made pioneering X-ray studies of wool in its natural and stretched states, which he christened the α-and β-forms. He surmised that in its unstretched α-form, the wool protein fibre was folded, and that this property was shared by other keratins such as hair, feather, and even the porcupine quill. From fuzzy X-ray photographs of fibrous proteins, Astbury observed that the diffraction pattern repeated itself every 5.15 Å along the longitudinal axis of α-keratin fibres. He emphasized this fact in a letter to Sage as early as February 1931: ‘The important fact is that the main periodicity of alpha-hair is about 5.15 Å.’3 5.15 Å was the distance that would dominate thinking about protein structure for the next two decades.

  For the first year or so, Astbury worried about how proteins that were chemically diverse could adopt an identical physical form, as revealed by X-ray diffraction patterns. This was why he urged Bernal, ‘night and day, to get me the dimensions of the molecules of glycine, alanine, leucine, glutamic acid and arginine’.4 He wanted to know the exact sizes of the constituent amino acid residues so that he could understand how they would fit together in an α-chain. But by the time he published some pictures of the structure of feathers in 1932, Astbury was more relaxed. He wrote to Sage:

  I am no more worried about the problem of why proteins can have such varying chemical analysis, and yet be the same thing and give the same X-ray photos. It seems to me that this is the first definite proof that proteins are really and truly gigantic molecules built to patterns of heroic proportions. I can see now quite clearly the structural basis of life – I couldn’t see it from silk or wool, the pattern was (apparently) too small – out of all the possible permutations of the protein chain, it seems to me, now that we have demonstrated the ease with which even the patterned permutations are built, then all the other permutations are not only equally possible, but also more probable. Anything and everything can happen – in fact, almost everything has happened.5

  In his 1947 Guthrie lecture delivered to the Physical Society in London, Bernal reflected on how his work, Astbury’s, and that of Hopkins’ Dunn Laboratory had reinforced Engels’ dictum about proteins being the essence of life. He claimed that scientific advances had made this hypothesis more precise, but his exposition of the subject was almost as speculative as Astbury’s breathless letter had been.

  So many of the chemical reactions occurring in living systems have been shown to be catalytic processes occurring isothermally on the surface of specific proteins, referred to as enzymes, that it seems fairly safe to assume that all are of this nature and that the proteins are the necessary basis for carrying out the processes that we call life. Now although since the great work of Fischer we know that the proteins consist of various combinations of some twenty amino acids, we still do not know the precise structure of any of them. But we do know that they have a precise structure, and we have a reasonable hope of determining it in the not so very distant future. It is perhaps significant that though the number of different proteins may be counted in tens of millions, this represents an insignificant proportion of the possible combination of twenty amino acids. The most likely explanation is that certain sub-units containing the same amino acids in the same order must occur over and over again.6

  The eagle-eyed Pirie still managed to object to the vital role that Sage seemed to grant proteins as a force in the evolution of life. Pirie wrote ‘I think proteins are only a necessary part of present-day life because they work better, as matches work better than flint and steel. There is no reason to think of them as original.’7 Bernal hastened to agree that there must have been ‘proto-proteins with a smaller number and simpler arrangement of amino acids… that did inefficiently some, but just enough, of the things proteins do today’. Regardless of Pirie’s point, Bernal maintained that the present day ‘very sophisticated and highly differentiated’ protein molecules governed the processes of life. When the lecture was subsequently published, Pirie dismissed it as ‘unsatisfactory’, in a review titled ‘Vital blarney’. He did say, in Sage’s defence, that some had compared it to Schrödinger’s short book What is Life? but it was not as bad as that! Tongue-in-cheek, he advised Sage to stick to his lasts of crystallography, politics, building, bomb-damage, ethics, history etc., for which he needed as many arms as Briareus.* Pirie thought Sage wrote with such authority and conviction on those subjects that ‘we must put down to pure Irish whimsy his decision to write a book on life’.8

  While Astbury and Bernal trusted that the structure of proteins would emerge over time from X-ray diffraction studies of these large, complicated molecules, Linus Pauling at Caltech took the opposite tack that it was first necessary to establish as much detail as possible about the molecular structure of the constituent amino acids and in particular to understand how they linked together. Coming to X-ray crystallography from a chemistry background, Pauling had also embraced quantum theory, and by the late 1930s was the world’s leading authority on chemical bonds. In 1937 he recruited a research fellow from the Rockefeller Institute, Robert Corey, to come to work with him in California; they decided to launch a systematic
attack on the molecular structure of amino acids and small peptide molecules by X-ray diffraction. When Pauling reviewed the published literature on the subject, the only worthwhile paper he could find was Bernal’s from 1931. In that short publication, Sage had promised ‘a detailed account of the crystallographic investigation with a discussion of its chemical implications will be published at a later date’9 – which it was by Corey in 1938!