Einstein and Common Sense
WATCH Out, all you believers in common sense. Albert Einstein was born on this day in 1879 and it is interesting to consider the effect of the scientific revolution caused by his theories on the “common sense” view of the world.
In 1905 (while working in a patent office), Einstein published his first paper on Special Relativity (“On the electrodynamics of moving bodies”—Annalen der Physik). From two beautifully simple axioms (the principle of relativity and the constancy of the velocity of light), Einstein was able to come up with some startling results. One of the best known is the prediction that moving clocks run slow. To quote his original example: “Thence we conclude that a balance clock at the equator must go more slowly by a very small amount than a precisely similar clock situated at one of the poles under otherwise identical conditions”.
Another prediction that violates “common sense” is that the relative velocity of two observers moving directly away from each other, is not equal to the sum of their velocities. For example, if two spaceships move off from the earth in opposite directions at half the speed of light (relative to the earth) then their relative velocity will not be equal to the velocity of light (the answer predicted by classical physics and “common sense”) but only 80 per cent of it. The original reactions to these apparently nonsensical theories were mainly hostile. W.P. Magie in his Presidential Address to the American Association for the Advancement of Science dismissed relativity theory, saying:
“I do not believe there is any man living who can assert with truth that he can conceive of time which is a function of velocity or is willing to go to the stake for the conviction that his “now” is another man’s future or yet another man’s past.”
The hostile reception to his theories meant that Einstein had to work for another four years in the patent office before he got a job as a physicist.
The first experimental tests of relativity theory (Kaufman, Annalen der Physik 1906) were not compatible with Einstein’s theory and favoured rival theories. But Einstein was not unduly worried:
“In my opinion both theories have a rather small probability because their fundamental assumptions concerning the mass of moving electrons are not explained in terms of theoretical systems which embrace a greater complex of phenomena.” (Mach, Einstein and the Search for Reality by G. Holton, p 651/2).
In other words, Einstein was convinced of the correctness of his theories not because of the empirical “facts” but because of subjective factors such as the simplicity and beauty of the equations. Of course, later experiments revealed flaws in the earlier ones, and gave results compatible with relativity However, the opposition to the theory continued and even when Einstein won a Nobel Prize in 1921 it was only partly for his theory and partly for same comparatively minor work.
There was also some more fanatical opposition, particularly in Germany and largely on political grounds (partly because he was a Jew and partly because be was thought to be attacking the great German philosophers like Kant). In 1934, twenty five years after the publication of his first paper on relativity, a book was published in Germany called 100 Authors Against Einstein. Typical of the relativity “sensible” attack was that by Professor Strehl:
“The theory of Einstein is for me a functional deformation of reality, his framework of references, variable space and time coordinates, invariant velocity of light (in spite of variable limiting value) is not to my taste.” (Die Naturwissenschaften II (1931) p 234/6).
The relevant point is that “common sense” is based on generalisation of everyday experience in which bodies move very much more slowly than light, and that therefore the effects of special relativity are negligibly small. Attempts to extrapolate these laws to velocities approaching that of light (300,000 kms per sec) give results which are qualitatively wrong. To physicists working with particles moving with velocities within a fraction of a percent of the velocity of light, the effects of special relativity are so common that the laws of relativity become part of their “common sense”.
An analogy between relativity and socialism should not be taken too literally, but what should be remembered is that the history of science is full of revolutions which violated the prevailing “common sense” view of human nature (humans are innately greedy, aggressive and so on) because this view is based on generalisations made in capitalist society. The extrapolation of this view of human nature to a qualitatively different society — socialism — is therefore completely unscientific. Those people who reject socialism on these grounds are making just as big a mistake as those philosophers who rejected relativity because it violated the internal infallibility of Kant.