Collected by Alfred 0. Garret)
Ohio State University Columbus
The Flash of Genius, 1
The Nuclear Atom: Sir Ernest
v e r y little progress was made in learning about the structure of atoms for 100 years following Dalton's enunciation of the atomic theory (about 1805). The concept of Dalton's day and for many years later was that the atom was a hard, indivisible, solid sphere. In the latter part of the century, with the development of the concept of the electrical nature of matter, r e find the J. J. Thomson "raisin pudding" model which describes the atom as a matrix of positive and negative charges of electricity. I t remained for Sir Ernest Rutherford, a brilliant student of Thomson's, to solve the problem in 1911. Radioactivity had been discovered only a few years before, in 1896, and the Curies had isolated a radium compound. Rutherford made use of the new tool-the high-velocity, high-energy alpha particles produced by some radioactive substances-to bombard elements and gather information about the structure of their atoms. He described' how he got the ideaof the nuclear :,tom2 as follows:
somehow with negative charges. A year or two later, J J. Thomson elaborated this idea and calculated how negative electrons would distribute themselves throughout a sphere of positive charge. He was able to explain in this way the fundamental nature of the periodic table. "Now I myself was very interested in the next stage, so I will give you it in some detail, and I would like to use this example to show how you often stumble upon facts by accident. In the early days I had observed the scattering of wparticles, and Dr. Geiger in my laboratory had examined it in detail. He found, in thin pieces of heavy metal, that the scattering was usually small, of the order of one degree. One day
. . . We now turn to consider the question of atomic structure. In 1895 Lennard made a famous experiment in which he parsed electrons through a thin window in the discharge tube where they were made, and was Ale to observe them outside the tube. Since the electrons could penetrate the windows so easily he concluded that the atoms in the window must have a very open structure and have comparatively large spaces between them. He suggested that the atoms might contain spheres of positive electricity associated
F r o m a lecture given by Lord Rutherford a t Cambridge University in the series given by ten scientists on the "Background to Modern Science" in 1936. Edited and prepared for press by RATCLIFFE,J. A,, The Cavendish Laboratory, Cambridge. The two lectures given by Rutherford were "The History of Radioactivity" and "The Development of the Theory of Atomic Structure!' This excerpt was taken verbatim from the lecture, then edited and published in the book "Background to Modern Science,', The Macmillan Company, 1938, pages 67-69. RUTHERTOBD, SIRERNEST, Phil.Mag., 21,669-688 (1911).
How is a new idea born? What trips the trigger to produce the flash of genius, the crucial act in the discovery process, the ultimate revelation in the art of creativity? This series of papers is dedicated to an attempt to understand that trigger-tripping process. We have organized our search by collecting case studies of all types, especially in chemistry. No one type of discovery is given priority here; in each we may discover a helpful clue, or an inspiration to try to stimulate the creativity process. We shall describe-in the words of the discoverer, when possible-the key experiment or experiments that led to the discovery. The studies are selected a t random, ranging from the discovery of oxygen in 1774 to several modern ones. No priority will be placed on the assumed value of the discovery but rather on the art of the process. As we learn how each discovery was made we will find that r e can classify them as the result of (a) trial and error, (b) planned research, and (c) accident. Not all can be categorized clearly in one or the other of these classes alone; elements of all of these methods may be found in many. Can the discovery process be explained? The clue to discovery by the trial and error process depends heavily on doing enough experiments: one of them may eventually give the desired results. That was Priestley's method in the discovery of oxygen and also the early method used by Midgley, Boyd, and Hochwalt in the discovery of lead tetraethyl. The clue to the process in planned research depends heavily on the pattern or picture (theory to fit the facts) that forms as the data are collected. This was the method of Arrhenius in developing the theory of ionization, the work of Madame Curie in the isolation of compounds of polonium and radium, and the work in developing the nuclear reactor and atomic bomb. But how can discovery by accident be explained? Of the three types of the discovery process this is the one that is most
baffling to explain. At the same time, it is one of the most intriguing to study. Clues to understanding the trigger-tripping process of discovery by accident, include the following main factors: (a) "Chance favors the prepared mind" (a famous quotation from Pasteur), and (6) The element of serendipity is common to and perhaps essential to many discoveries. Serendipity ia a term that was coined by Horace Walpole in 1754. He had discovered the old fable of the princes of Ceylon (or Serendip). According to the fable these princes had the faculty of making happy and unexpected discoveries by accident. They were forever making discoveries of things for which they were not looking a t all while looking for something else. The term "serendipity" has been used to mean the faculty of having these happy coincidents; more recently it is sometimes used to describe the ability or acquired trait to recognize in everyday activities interesting and exciting phenomena. See, "The Arts," by Hendrik Willem VanLoon, Simon and Shuster, New York, 1937, page 64, for further discussion of serendipity. These two factors do not give the complete answer, but they help. In addition to these factors, in most discoveries we will no& the importance of careful observation, good imagination, an agile mind, persistent effort, and ability to see what is there even though it is not expected. The literature on creativity is extensive; i t is not appropriate here to try to provide even a selective bibliography. Notable in among the papers which have appeared in THIS JOURNAL recent years are those by P. Walden, 28, 304 (1951); G. Lockemann, 36, 220 (1959); and 0 . T. Benfey, 37, 467 (1960). Our plan is to publish one or two of these personal stories each month. The entire collection will appear as a book a t a later date.
Volume
39, Number 6, June 1962
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287
