Einstein, the searcher

by Alexander Moszkowski

It often happens that experiment acts as a corrective of the underlying idea, neither confirming nor contradicting, but nursing it, as it were, strengthening, and purging it of errors. Such experiments, partly in conjunction with chance, play an important, sometimes a decisive, rôle in the works of Dufay, Bradley, Foucault, Fresnel, Fraunhofer, and Röntgen. Faraday, who was incapable of observing otherwise than intensively, found himself compelled, whilst studying induction phenomena, to alter his initial view, and it is just this correction by experiment that constitutes Faraday's real discovery. In many cases the initial idea is corrected, nay surpassed, by the result. Columbus worked methodically when he set out to reach the East Indies by travelling westwards; but what he discovered was not a confirmation of his nautical idea only, but something much greater, which certainly did not lie in his calculation. Thus he became the archetype of all searchers, who had thought out and anticipated essentially different conditions from those that were afterwards discovered to be prevalent. Among these are to be counted Priestley and Cavendish, who clung to the erroneous notion of phlogiston, even when they had the evidence to the contrary in the elements they had themselves discovered, namely, oxygen and hydrogen. Graham Bell, the inventor, was seeking something quite different from what he later hit on: as a teacher of the deaf and dumb he was trying to give a visual picture of sounds, in order to make clear the formation of sounds to his pupils; this led him to construct an electrical apparatus, which finally led to the discovery of the telephone.

The truest and sharpest contrast with the experimentum crucis is furnished by experiment when it shows the exact opposite of what the explorer was expecting. But since an absolute No entails a very decisive Yes—namely, in this case, the affirmation of a relationship that was previously held to be impossible—a negative experiment of this kind, when it occurs, will be followed by momentous consequences; these will be the more important in proportion as the question, the affirmation of which was expected by the physicist, is of a fundamental character.

The experiments of Michelson and Morley, directed at proving the existence of the ether, are to be regarded as the true classical instances of these experiments answering with an overwhelming negative. Their first effect was to produce a sense of helplessness, a check to thought, a void in the chamber of ideas. And to fill this void there arose new views of the world in which we nowadays recognize the true thought-pictures of the universe. The great names—Lorentz, Minkowski, Albert Einstein—shone out!

As there are forerunners for almost every Important event, so also in the case of the experimentum crucis of Michelson and Morley. Henri Poincaré, the famous mathematician, whilst still a student of the École Polytechnique, had initiated experiments with his fellow-student Favé, which followed the same object. The Michelson-Morley experiment was at least a hundred times more accurate. In each case the conclusion was that the laws of optics are not disturbed by a motion of translation, such as that of the earth through space this is, however, contrary to what the old physical ideas lead us to expect.

If we assume the existence of a space-filling ether, the earth, owing to its own velocity of nineteen miles per second, would have to pass through a hurricane just as in the case of travellers sitting in an open train rushing along at very great speed. If we send out light rays in all directions simultaneously from any point on the earth's surface, some will travel in the teeth of the ether-storm, others will experience only a part of the storm's power; so that of two light-rays travelling in exactly opposite directions the retardation of the one should be equal to the acceleration of the other; and yet they are not quite equal, for a simple calculation shows that in every case the retardation is slightly more than the acceleration.

This may be made clear by means of a model of easy construction, or, better still, by considering a ship that is subject to a constant current and, simultaneously, to a pressure of the wind. The time taken by the boat in making a trip up and down stream can never be the same for the cases when the wind is in the direction of the current, and vice versa.

In the case of the ray of light, which is sent backwards and forwards by means of a contrivance of mirrors, this fact should be clearly demonstrated by means of the interference-fringes, which are able to show much smaller effects than the experiment demands. The experimental oracle was to speak, but it remained silent. This portentous silence signified: no interference-effect, no action of the ether-current, no influence due to translation—nothing!

This "nothing" compelled a decision of a very startling kind, for the result of this experiment was in direct contradiction to another famous experiment. Fizeau had proved that the ether is practically rigid and remains fixed in interstellar space. A decision had to be taken in favour of Fizeau or Michelson and Morley. Yet this was impossible, for both had operated with unsurpassable accuracy. It was impossible to reconcile both views as they were diametrically opposed. This contradiction remains, even if we assume a different hypothesis, not involving the ether, for Fizeau's experiment. A solution was impossible without undertaking revolutionary changes in the whole of physical thought.

This radical change was effected by Einstein; and this mysterious contradiction disappeared in the resulting revolution of thought. Einstein supplanted the absolute time-conception by a new relative conception, and thus the perplexing problem disappeared. Two great principles arose as regulative factors in thought, and wherever these were applied, they achieved wonders: one was the new conception of time that deprived the earth of her unique position as the sovereign of time by the introduction of the principle that the rate at which time elapses is different in media moving at different speeds; the other is the principle of the constancy of the velocity of light. One feels a temptation to apply a mythical allegory: just as the world, according to the Biblical story, originated from nothing, so there arose from the "nothing" of the Michelson-Morley experiment a new world, a world of knowledge, a cosmos of thought, in which perfect harmony reigns.

Its truth was contained in itself before the experimental proof was furnished. And this realization of truth has become a fact in the experimentum crucis for which the sun and stars formed the material. This will be discussed in another part of the book.