To say the truth, it would seem that nothing here below so much reveals the mystic presence of the divine as does the eternal and inflexible harmony that unites phenomena, and that finds expression in the laws of science.
Is not this science which shows us the vast universe well-ordered, coherent, harmonious, mysteriously united, organised like a great mute symphony, dominated by law instead of caprice, by irrefragable rules instead of individual wills—is this not a revelation?
There you have the only means of reconciling the minds which are devoted to external realities and those which bow to metaphysical mystery. To talk of bankruptcy of science—if it means anything more than to point out human weakness, which is, alas! obvious enough—is really to calumniate that part of the divine which is accessible to our senses, the part which science reveals.
In sum, the whole Einsteinian synthesis flows from the issue of the Michelson experiment, or at least from a particular interpretation of that issue.
The phenomenon of stellar aberration proves that the medium which transmits the light of the stars to our eyes does not share the motion of the earth as it revolves round the sun. This medium is known to physicists as ether. Lord Kelvin, who was honoured by being buried in Westminster Abbey not far from the tomb of Newton, rightly regarded the existence of interstellar ether as proved as fully as the existence of the air we breathe; for without this medium the heat of the sun, mother and nurse of all terrestrial life, would never reach us.
In his theory of Special Relativity, Einstein, as we saw, interprets phenomena without introducing the ether, or at least without introducing the kinematic properties which are usually attributed to it. In other words, Special Relativity neither affirms nor denies the existence of the classic ether. It ignores it.
But this indifference to or disdain of the ether disappears in the theory of General Relativity. We saw in a previous chapter that the trajectories of gravitating bodies and of light are directly due, on this theory, to a special curvature and the non-Euclidean character of the medium which lies close to massive bodies in the void—that is to say, ether. This, therefore, though Einstein does not give it the same kinematic properties as classic science did, becomes the substratum of all the events in the universe. It resumes its importance, its objective reality. It is the continuous medium in which spatio-temporal facts evolve.
Hence in its general form, and in spite of the new kinematic attitude which is ascribed to it, Einstein’s general theory admits the objective existence of ether.
Stellar aberration shows that this medium is stationary relatively to the orbital motion of the earth. The negative result of Michelson’s experiment tends, on the contrary, to prove that it shares the earth’s motion. The Fitzgerald-Lorentz hypothesis solves this antinomy by admitting that the ether does not really share the earth’s motion, but saying that all bodies suddenly displaced in it are contracted in the direction of the movement. This contraction increases with their velocity in the ether, which explains the negative result of the Michelson experiment.