A Tool, Not a Creed: An Answer to Stephen Leacock
» In the Atlantic for June, Stephen Leacock spoke with laughable incredulity about his friends, the scientists.
by A. VIBERT DOUGLAS
IT is good to stand aside sometimes and laugh at our own solemnity; but having laughed at the many brilliant witticisms in Stephen Leacock’s “Common Sense and the Universe” and chuckled at the hard knocks given the cosmologists and physicists, we pause to ponder how very few men of letters, men nurtured in the non-scientific branches of learning, have any real appreciation of the intrinsic beauty of modern physics and astrophysics. They catch nothing of the thrill of the chase as observation and theory, like a pair of hounds, leap forward, first one leading, then the other, up hill, down dale, now into a cul-de-sac, then retracing and off again with a fresh scent.
A great man and teacher, Sir Joseph Thomson, pre-eminent as a physicist in his day, was wont to say to his classes in the Cavendish Laboratory, “A theory is a tool, not a creed.” A tool, not a creed! Burn this into your minds, ye men of letters, who picture science as if it were a random game of ninepins. You portray the man of science as sadly lacking in ordinary common sense. You see him setting up a theory like a ninepin. After it has stood for some time, long or short, some ball knocks it down. Then from the non-scientific public on the side lines come cheers of derision, kindly perhaps or gently mocking. You see one pin knocked over and another pin set up, and the less you comprehend its significance the more eagerly you hail its eventual downfall as fit occasion to poke fun at the bowlers and make merry over the futility of the game.
A theory is a tool, not a creed. The purpose of a tool is to fashion something, and any craftsman will tell you that a tool has justified its existence if it has helped to fashion a better implement than itself. This is the attitude of mind to be adopted in gauging the value of any scientific theory. Has it been useful in pointing the direction in which new knowledge has been found; has it been fruitful of new ideas; has it been the basis from which, by deduction, crucial tests of its own validity or adequacy have been formulated? If so, and even if the crucial tests lead to its own overthrow, its existence has been justified; its very downfall may be its own triumph.
Thus the reaction of a scientist when a theory requires drastic modification or is discarded in favor of another is not one of humiliation and chagrin. While his nonscientific friends are laughing at him and his theories, he laughs to himself, happy because progress is being made, happy because a new challenge is laid before his eyes, and amused probably because, in watching the amusement of the crowd of onlookers, he sees that they have really missed the point!
Let us take this matter of the speculations of the cosmologists which led the humorous critic of science to say, “We begin to doubt whether science can quite keep on believing in and respecting itself.” I think he has missed the point on more counts than one. Hubble’s latest researches have not restored some Elysian status quo, nor has the cosmologist any reason to do otherwise than hold his head high, for his speculations and investigations during these past twenty-five years provide one of the most thrilling records of scientific method and imaginative daring in the history of modern science.
The Michelson-Morley experiment provided a challenge to the comfortable cosmology of the last century. Einstein had the courage and daring to venture out into a non-Euclidean deep. De Sitter deduced the observational tests of Einstein’s theory and drew special attention to the apparent recession of the distant galaxies as measured by the red shift of their spectrum lines. Lemaître, to explain this, propounded his theory of the expanding universe — but let it be said very clearly that this was not a creed: it was a tool. Hubble took this tool and with its aid carved out an observational program designed to test the temper of the steel of which the tool was made. The test throws heavy doubt upon the expansion theory and, in so doing, it resurrects an old problem with a new urgency: What principle of nature, as yet unrecognized, is responsible for the red shifts of the spectrum lines if these may no longer be interpreted as indicating velocity of recession? This becomes a ringing challenge to both physicist and astronomer.
But the last word has not yet been said on the hypothesis of expanding space. Already the hounds are off on a new scent. What an international record this chase provides! There have been contributions from America, Germany, Holland, England, Belgium, and now the intensely interesting work just reported by the Indian scientist, Chandrasekhar. He has been inquiring under what conditions of nature the basic units of matter — electrons, protons, neutrons, positrons — could be expected to come together to form, in their various proportions, the atoms which make up the elements familiar to the chemist. As these elements compose all stellar bodies as well as all things terrestrial, their synthesis is a cosmic problem. He finds that such tremendous extremes of high temperature and high density would be required that it is necessary to suppose that all the matter of the known universe was once confined to a volume of radius only about twenty times that of the solar system. Such a sphere drawn around our sun as center does not now contain a single other star. Yet into such a volume there may once have been packed not only all the thousand million stars of our own galaxy, but all the millions of other galaxies. This is indeed a picture reminiscent of the “giant molecule” of Lemaître.
Since stars and galaxies are not now thus packed, expansion must have taken place some time very long ago. If, as Hubble’s conclusions imply, expansion is not still in progress, we are faced with yet another problem: that of how cosmic expansion was checked. One can always claim that some advance has been made when it is possible to formulate new questions.
This chase has led into strange territory. The trail has sometimes doubled back upon itself, but always the hunt presses on, the hounds are in full cry. Happy are they who can feel something of the excitement and thrill of these great and daring adventures of the mind.