The nature of the physical world / by A.S. Eddington.

  • Eddington, Arthur Stanley, Sir, 1882-1944.
Date:
1928
Catalogue details

Licence: In copyright

Credit: The nature of the physical world / by A.S. Eddington. Source: Wellcome Collection.

    214/392 (page 190)
    Different views may be held as to how the prize¬ drawing is conducted on the sweepstake theory. Some hold that the lucky part of the wave-front is already marked before the atom is reached. In addition to the propagation of uniform waves the propagation of a photon or “ray of luck” is involved. This seems to me out of keeping with the general trend of the modern quantum theory; and although most authorities now take this view, which is said to be indicated definitely by certain experiments, I do not place much reliance on the stability of this opinion. Theory of the Atom. We return now to further experi¬ mental knowledge of quanta. The mysterious quantity h crops up inside the atom as well as outside it. Let us take the simplest of all atoms, namely, the hydrogen atom. This consists of a proton and an electron, that is to say a unit charge of positive electricity and a unit charge of negative electricity. The proton carries nearly all the mass of the atom and remains rock-like at the centre, whilst the nimble electron moves round in a circular or elliptic orbit under the inverse square-law of attraction between them. The system is thus very like a sun and a planet. But whereas in the solar system the planet's orbit may be of any size and any eccentricity, the electron’s orbit is restricted to a definite series of sizes and shapes. There is nothing in the classical theory of electromagnetism to impose such a restriction; but the restriction exists, and the law imposing it has been discovered. It arises because the atom is arranging to make something in its interior equal to h. The inter¬ mediate orbits are excluded because they would involve fractions of h, and h cannot be divided. But there is one relaxation. When wave-energy is