Science and Mankind

WLbragg
Sir Lawrence Bragg about the time this article was written. 		A talk by Sir Lawrence Bragg, F.R.S., Cavendish Professor of Experimental Physics in the University of Cambridge, broadcast on Sunday 26th August 1945 on the BBC Home Service: (from Bristol)

(The manuscript of the following article was "discovered" by Mike Glazer while clearing out a laboratory at the Clarendon. We thought that it greatly deserved reappearing 60 years after it was written, and I am delighted to say that Sir Lawrence's daughter and literary executor, Mrs Patience Thomson, thought so too. We are also grateful to the encouragement given by Professor Frank James, keeper of the Bragg archive, for his encouragement. - Ed.)

I was asked last year to give a Sunday evening postscript on 'The Spirit of Science'. At that time, the progress that was being made toward using atomic energywas a closely-guarded secret. Now the world knows that another tremendous new power over nature has been added to those which science has already given us. Where are we heading, and what is the significance of the vast changes in the world which the progress of science is bringing about?

I will not try to forecast what atomic energy will do in the near future, for instance what changes it may bring about in power or transport. It is probably all too recent for anyone as yet to see clearly what may be possible, and at any rate, it is for the experts who have done the work to make such predictions. It is clear that a terrific power for good or evil has been created by this awe-inspiring success, but I will not try to guess its immediate political or economic implications. I want to attempt a long-range view and show its relation to past events in human history and its p ortent of things to come.

The use of the energy locked up in the nucleus of the atom has been compared to man's discovery that he could use fire. The old legend, that Prometheus brought down fire from heaven was based on a truth. The sun warmed man by day, but when it set he was left to face the cold and dark of night. By discovering fire, he found a way of bringing back at will the sun's warmth and light stored up as energy in the fuel he burnt. Much later, in very recent times, he found another use for the storsed energy by making it develop power. The energy which the sun poured down long ago on the tropical forests of the coal measures appears again as light and power in our homes. But the latest atomic fire which has been stolen from heaven comes from a far more distant past and more awe-inspiring source than the sun's heat. It was imprisoned in the nucleus in some great cauldron when the stars were made, in regions packed with energy to an almost unimaginable extent. There, prodigious forces wound up the springs which the atomic explosion reeases. It has been called cosmic force, it is of a different order altogether to the gentle changes in the outer envelope of the atom, where energy is stored up by the sun's mild rays and can be released again when we burn our fuel. There is one question which man must be asking. If these vast stores of energy are present in the atmosphere all around us, is there not a danger that further success in exploiting them may touch off the whole world like some vast magazine? Sometimes a star blazes into brief glory in the heavens and wanes again to insignificance. It was often jestingly said that a new star like that was a world where the experiments in atomic disintegration of another Rutherford had been only too successful.

Well, that joke may not appear so wildly improbable now, but I think we can be reassured.... For if the whole world had been of this explosive kind, some accident would have fired it off long ago without our intervention.

The actual production of the atomic bomb has staggered everyone's imagination as an example of what the application of scientific discovery can bring about, but I think it is worth while once more to underline the distinction between science and the uses to which it can be put. Here is a contrast which I would like to present to you. We have all seen pictures in the papers of the vast plants assembled in America to produce the bomb, and have been told of the hundreds of millions of pounds that were spent on it. Now, in the Cavendish Laboratory at Cambridge we havse a little museum in which are displayed some of the pieces of apparatus with which historical experiments have been made. There are two such examples, simply constructed little gadgets one can hold in the hand One of them is the vessel in which Rutherford observed the scintillations which told him that nuclei were being broken up by the rays from radium; the other is the device with which Chadwick made experiments which led to the discovery of the neutron: Those experiments were made in the search for pure knowledge, Rutherford's just after the last war, and Chadwick's in 1932 and at the time must have seemed as utterly remote from any possible practical application as any scientific discovery could well be. But it's such experiments as these and similar ones made in other countries, Germany, Italy, and Austria as well as Britain and America which represent the scientists' contribution to the atomic bomb. People are apt to talk of the scientists turning their energies to inventing terrible engines of destruction, the internal combustion engine, the V weapons, and now the atomic bomb; but it does not happen in that way. Scientists accumulate a store of knowledge which can be used for any purpose, good or evil. In the stress of war, as the President of the Royal Society puts it, science, as an unwilling conscript, has become the direct agent of undiscriminating devastation. The scientist explains what he knows to the statesmen who guide policy and the engineers who plan production on a vast scale. How could he possibly withhold his help when his country is at war? It is war which is wrong, not science which knows no national boundaries and enjoys a world-wide co-operation in the dis interested pursuit of knowledge.

The far-reaching result of some simple initial experiment is a familiar story, electricity provides many examples. But there are two aspects of this latest achievement which are portents of things to come. The vast technical effort in America needed to produce the bomb was an act of faith different in scale to anything which has happened before. The scientific knowledge had been gained with the most minute quantities of material, which could not be detected except by refined experiments. The huge enterprise was based not on experience of anything which had gone before, but on a pure idea, on deductions made by a small band of scientific experts whom the statesmen were willing to trust. And again, the enterprise is an example of the collaboration of experts on a scale such as the world has never seen before. No other single undertaking has ever drawn together such a galaxy of talent from many countries. It is tragic that the end in view was the production of a destructive weapon, but as an example of what can be done, it is the greatest interaction of brain effort in history and real1y does mark the beginning of a new era.

For what is the main lesson to be learned from the atomic bomb? It is surely that which has been emphasised in many of the letters and articles which have appeared since the news of its achievement was announced. The whole world is becoming far more closely knitted together than it ever was before. Ships, trains, aeroplanes, telegraph, telephone, and radio have supplied it with blood vessels and nerves which link all countries together in an organic unity, and what happens in one part of the world may intimately concern the opposite ends of the earth. The general tendency of increased ease of communication and interdependence has been to bring about larger political groups. Paradoxically, in increasing complexity and deadliness of weapons has on the whole been an effective way of bringing people together, teaching them better manners, and making life safer. With the war just over fresh in our minds you may think this a rash statement, but is it not true? When a stout right arm and a stick or knife were all-powerful, men had to go about their business even in time of peace armed for their own protection. A child could now kill a grown man with a tiny automatic - but we walk abroad without fear of attack and any one who disturbs the peace is hounded down by society as a criminal. Confronted by this danger, society produces a cure. To pass from individuals to nations. When rifles and a few guns were all that was needed for a campaign, a number of small private wars were always going on while the rest of the world looked on as spectators. We are now so interdependent, and preparation for war is so complex an undertaking, that once the conflagration starts it spreads over the globe which divides itself into two hostile camps. Now, may we not take comfort from the fact that the only number less than two is one? For I join with the optimists who think that the inevitable end of our scientific and technical achievements is a world welded into one unit just as Great Britain, once a collection of little warring kingdoms, is now united. I even dare to hope that the last great achievement, atomic energy, may mark the final turning point and that we have seen the last great war - (unless some hothead in the future leads our descendants into the adventure of a campaign against Mars).

The discovery of how to release atomic energy is one more example, the most striking as yet, that something very big is happening just now. We are living at the beginning of one of those epochs when the whole structure of human society undergoes a vast change and reorganisation. These epochs come at long intervals, measured in tens of hundreds of thousands of years.

The command over nature given by science is a discovery of the same magnitude as the first use of fire, or of domestic animals, or of agriculture and it is bringing about, as they did, a general transformation of the kind of life it is possible for human beings to live.

We can best understand what the effect of science is going to be by recalling the effects of those other great discoveries. They must have brought many difficulties and disturbances in their train, but each meant in the end one more step away from the animal-like life of the primitive savage.

Power to control nature is not in itself civilization, but it is the foundation on which civilization is built. Each time that this power has been increased in the past, it has made possible a richer life, with higher forms of art, ethics, and religion - the standards by which we measure civilization.

What has happened in the past will happen again.

Lawrence Bragg, August 1945

Notes from the Webeditor: