THE ATOM BOMB

Evening Post, Volume CXL, Issue 150, 22 December 1945, Page 9

THE ATOM BOMB

A CLASSIC REPORT

TRIUMPH OF SCIENCE

(By H. H.)

The story of the greatest scientific and technological achievement in history, the practical harnessing of atomic energy, has been recorded in a very remarkable book, which seems destined to be known for many years as "The Smyth Report." A few copies have reached New Zealand, but it is not yet on sale.

This is the account written by Dr. H. D. Smyth, of Princeton University, at the request of Major-General Groves, United States army, "of the development of methods of using atomic energy for military purposes. . . ." It is a book of the greatest importance, for, as General Groves says in a foreword, it gives "all pertinent scientific information which can'be released to the public at this time < August, 1945) without'violating the needs of national security." Where such security-dictated suppressions oc- ; cur, the fact is usually stated in the book; and the impression left on reading it is that it is in the circumstances extraordinarily frank, and that most of the suppressions relate to technical rather than scientific points, though the author remarks that "many interesting developments have been » omitted." Dr. Smyth points out that ■ the book is written for scientists and > scientific students, a "semi-technical 1 report which it is hoped men of science 1 . . . can use to help their fellow- > citizens on reaching wise decisions. The ■ people of the country must be informed if they are to discharge their responsibilities wisely." The author was one of the great team of scientists i engaged on the project. • ■ --:1 Written as it is for readers who have ! at least a moderate acquaintance with ' the ideas and language of modern ■ physics, the report is nevertheless [ easily and enjoy ably readable by people ' who have no such grounding; and so ■ read, it is an impressive and even exciting -story of the greatest scientific and technological feat in history—a ! feat which in a way may rank with ' the vast labour that went into the ; building of the Pyramids. It is also the record of convincing proof on a ■ magnificent scale of the fact that by the exercise of exceptional intelligence . and mathematical skill, a few men have ! been able to reach deep into the secrets ', of Nature, with almost no material ! facts to guide them. The apparently [ mystical and fantastic theories of the , higher-physics defy expression in clear language. As one writer put it, a few years ago, "the ultimate concepts of physics have, it seems, to be left ir ' the decent obscurity of mathematical . equations." Yet it is out of mathematical equations, and one in particular, ', that atomic energy became a practical fact. FUNDAMENTAL EQUATION. One of the outcomes of Einstein's : relativity theory is that matter and energy are equivalent. The old "laws" , of the conservation of matter and the conservation of energy have been replaced by the law of the conservation of matter and energy jointly. The relationship between them is expressed in an equation of only three symbols, meaning that the energy equivalents to matter is equal to the mass multiplied by the square of the velocity of light —an idea which most people find totally incomprehensible. Yet atomic energy derives precisely from the conversion of small quantities of matter Into great quantities of energy. Ever since this transformation was written, the idea has been talked about, written about, played with, and worked with; but with no realisation till war forced the issue, of how stupendous an undertaking it would be toput'it into effect, Dr. Smyth's report tells the story In its first sections it gives an outline, exceptionally clear for the relatively ignorant, of the new atomic physics, developed from the discovery of radio-activity and the basic researches of the Curies and Rutherford and his successors, and the relativity theory. ■ ■ ■- One of the most powerful- impressions created by reading this book is caused by the evidence of the combination of patience, confidence, and daring which characterised the work and those who sponsored it. Space does not permit any enumeration of the institutions and persons who joined in this vast, undertaking; the report contains an impressive roll. It is of more interest to note, in principle and without quotation, some of the broader features of the great project. As is well known, the whole phenomenon of the release of atomic energy rests upon the peculiar behaviour of the rather rare metal uranium when subjected to bombardment with neutrons, which are not, in any ordinary sense, material, but are fragments of atoms, and which for practical use have themselves to be artificially produced by the breaking up of atoms. THE GREAT DISCOVERY. The phenomenon of the "fission," or splitting of the uranium atom, was only discovered at the end of 1938. It was found to be accompanied by an extremely minute loss of weight: this meant energy. The discovery immediately caused intense interest in scientific circles in every country. When the war began, American scientists, realising the possibility of u^ing atomic energy as a weapon, took prompt steps to bring the matter under attention, and it was at their instigation that the great research was undertaken. Up to that time, the phenomenon was known only as laboratory experiments on the most minute scale; what knowledge - there was was almost wholly wrapped in "the decent obscurity of mathematical equations." But .there was unlimited human energy,'unlimited money.

It must be realised that the task was to produce a weapon, not an industrial asset; and this shaped the direction of the research. ,In the end, enormous energy was obtained—and discarded: this side of the research is still to produce its results.

An explosive could be made in two ways—by separating a small fraction .of uranium (U235) from the - rest t (U238), or, by converting U238 into a new element, plutonium, which has the same "fissionable", nature as U235. The separation is extraordinarily difficult, for the metal has literally to be sorted out atom by atom, by the difference in the weights (235 compared with 238). In the earlier researches, this was done with quantities too small to see; at the end, vast machines (on which nothing moved) were used, and tons of metal were broken down into separate atoms and sifted by invisible agencies. Plutonium < was made, also in completely silent and immobile, devices, which were in fact stacks of carbon blocks (made, moreover, of carbon so pure that a new industry had to be created to produce it) with pieces of uranium distributed among them. The uranium, partly, converted into Plutonium, was dissolved and the new

metal extracted by chemical processes. All the operations resulted in the production of intense radioactivity, against which the' utmost precautions had to, be taken, for the safety of the workers' and neighbourhood; an explosives factory was nothing to it. LONG SHOT COMES OFF. In many of the developments it was possible to work, stage by stage, from small • experiments to "pilot plants" and then to large scale working; but in others this was not possible, and a clear jump was made from a microscopic sample to operation on the full seale —and the scale was gigantic. It was in such steps as these that the confidence and daring (or was it only confidence?) of the scientists were best i displayed. In the end, it was again demonstrated; for, ■ when the first atomic bomb was assembled for test at Los Alamos, New Mexico, only cqnfi--1 dence in the rightness of calculations i could be relied upon. No small scale j experiment was possible, for a small quantity of the bomb material will not explode. On the other hand, more than a certain quantity will, and nothing will prevent it. How the "load" for the bomb was designed is one of the most interesting sections (though brief) in the whole report, especially as the book ends with a chapter beginning "the end of June, 1945, finds us expecting from day to day to hear of the explosion of the first atomic bomb designed by man.", The test explosion took place on \ July 16. Tlie calculation* were correct. I