[141] Bergson, “Durée et Simultanéité.”
[142] Bertrand Russell, article on non-Euclidean geometry in the Encyclopaedia Britannica, and various other writings. We may note, however, that Russell has recently modified his views on this subject.
[143] Whitehead, “The Principle of Relativity.”
[144] Both attempts failed.
[145] Quantum phenomena would now appear to account for what Ritz ascribed to that new entity, the magneton.
[146] We might also mention the annual variation in the angle of aberration of a star, and its relationship with the star’s parallax. This relationship would appear to be utterly mysterious.
[147] Italics ours.
[148] Kant’s attitude towards Newton’s absolute space is somewhat confused. At times he defends the absoluteness of space, making extensive use of the arguments of Newton and Euler. At other times he presents his own arguments in favour of the relativity of space and motion. Finally, in his last work (Metaphysische Anfangsgründe der Naturwissenschafften), he writes: “Absolute space is, then, necessary not as a conception of a real object, but as a mere idea which is to serve as a rule for considering all motion therein as merely relative.” How motion can be relative while space is absolute is a problem that Kant fails to elucidate. At any rate, the problem of the absoluteness of space and time in classical science refers not to the essence of space and time (a problem which would degenerate into one of metaphysics, hence which would be meaningless to the scientists), but solely to a discussion of those conceptions which are demanded by the world of experience. Hence we may realise that a man ignorant of mechanics is in no position to pass an opinion one way or the other. And Kant’s knowledge of Newtonian mechanics was extremely poor, to say the least.
Thus, in his Allgemeine Naturgeschichte und Theorie des Himmels, we find him giving incorrect formulæ for the most elementary facts concerning falling bodies. Then again, basing his arguments on what he claims to be the laws of dynamics, he tells us of a nebula which would set itself into rotation owing to its outer parts falling towards the centre and rebounding sideways against the inner parts. But this hypothesis is in flagrant opposition to the principles of dynamics, and had Kant spoken of a man pulling himself up by his bootstraps he would have given expression to no greater absurdity. Whereas this latter statement would violate the principle of action and reaction, Kant’s violates the invariance of the quantity of moment of momentum in a self-contained dynamical system.
[149] The development and gradual acceptance of the kinetic theory of gases is particularly instructive in this connection. Some two centuries ago Daniel Bernoulli had suggested that the tendency of a gas to expand might be attributed to a rushing hither and thither of its molecules. But inasmuch as the idea was not worked out quantitatively, no great attention was paid it. Not till a century or so later was it investigated in a mathematical way by Maxwell and by Boltzmann. For this reason these scientists receive the credit for the kinetic theory; and Bernoulli’s name (in connection with this theory) has lost all but a historical interest. Maxwell’s and Boltzmann’s theoretical anticipations were borne out quantitatively by the experiments performed in their day, and a large number of scientists accepted the theory as sound. Even so, the doctrine still had its detractors, for subsequent experiment proved that in the matter of specific heats at low temperatures, theory and observation were in utter conflict. Further difficulties related to the problem of the equipartition of energy. The net result was that other physicists (Kelvin and Ostwald in particular) were hostile to the kinetic theory.