The Stochastic Method frequently pride themselves on how SCIENTISTS logical they are, how they never accept anything until it is proved. The facts are, however, that little is or perhaps ever can be proved. Newton did not prove his law of gravitation; he suggested an inverse square law of attraction and tried it out on observations of the moon's orbit. It did not fit. Years later the distance of the moon was recalculated and Newton realized his theory did not account for the facts. In this century Einstein developed a more general gravitational theory which was found to account more accurately than the simpler Newtonian expression for the motion of the planet Mercury. r ewton, having a Teal understanding of scientific methods, would have accepted relativity before most scientists, who had difficulty incorporating the new theory into their "common sense" experiences. Dalton's law of the constancy of combining proportions is taught in all our schools as having been proved; and further that it proves the atomic theory. Actually, first it is not true in a great many cases of even the simplest minerals (for example, iron oxide), and, second, it does not really prove anything even if true. Dalton's law accounted for the facts as then known; the present atomic theory gives a reason for Dalton's, and several other, laws. Psychologically, these "laws" were derived by first conceiving them, and then seeing if they fitted the facts. This is the stochastic method, used almost universally in modern science. For instance, to find out the structure of a complicated crystal from xray or electron-diffraction patterns one first assumes a structure, then computes the x-ray or electron-diffraction picture one would get from the assumed structure and then compares this pattern with the observed. If it is substantially identical, the structure is "proved." In many cases, it is very improbable that any other radically different structure would fit the facts any better, but nevertheless the structure has only been derived by the stochastic method, and the possibility remains that another structure might fit the facts. Few scientists would admit that this method also lies at the foundations of the natural sciences, and it has become a term of disparagement to call a man an Aristotelian, i. e., one who conceives a theory and expects the facts to be in agreement with it. Aristotle used the stochastic method in describing natural phenomena quite successfully, except for the one infamous oversight of not testing his ideas of gravitation by experiment as was finally done by Galileo at Pisa. The conception, however, cannot always be tested adequately by experiment. The Copernican theory that the planets revolve around the sun is not proved by
measurements of their motion; one can still account for planetary motion by Hippocrates' epicycles. But, of course, the Copernican theory, its virility proved by the celebration of its 400th anniversary this year, gives a neater explanation having esthetic appeal. There are some fields, such as the motion of electrons around the nuclei of atoms, where the Copernican motion is not as neat a solution, and present theories are only accepted as tentative explanations. Copernicus showed that the earth is not necessarily the center of the universe; Poincar~ and Einstein showed that scientists in different situations may not get the same value for a measurement; Heisenberg showed that one cannot possibly measure all small things both simultaneously and accurately: so now physicists have become cautious and realize that theories and laws are not necessarily the final word. Nevertheless, there exists a solid body of pragmatic physicists, strongest in the New World, who have explicit faith in experimental measurements even of astronomical or of subatomic phenomena. In England Sir Arthur Eddington has been trying to derive a theory according to which even the most fundamental constants of nature, such as the mass of the electron, the gravitational constant, etc., may be calculated, crudely speaking, by our methods of measuring. The most famous of his efforts was the deduction that Planck's constant times the velocity of light divided by the square of the electronic charge was equal to the integer 137, rather than to some purely fortuitous "natural constant." This was ridiculed by some as being Aristotelian, but as measurements have been refined more and more during the last decade, the observed value has crept downward from 137.3 Ouly, 1929),137.2 (1937), 137.1 (1939), and most recently to 137.03 (August, 1941). The objection to Aristotelianism seems to be a psychological one; that theories should be based on experiment alone, and not that experiment should be used only to test and guide theories. Yet it is the latter, stochastic, method that is increasingly in wider use today. In thermodynamics, theory is supplying data more reliably than experiments can, and if Eddington's method develops successfully, there may be nothing in the universe that has to be measured except in confirmation. Of course an accumulation of a gteat amount of experiment and familiarity with a wide range of experimental material are necessary for a mental background before one can use this method to launch a project which will be accepted in the scientific world without accusations of megalomania.
-Iudustrial Bulletiu of Arthur D. Little, Iuc.
In tlte questJor new sources oj commercial alcoltol, the Germans are experimenting with units designed to recover bread-baking vapors.
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