The mysterious universe / by Sir James Jeans.

  • James Hopwood Jeans
Date:
1930
Catalogue details

Licence: In copyright

Credit: The mysterious universe / by Sir James Jeans. Source: Wellcome Collection.

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    as small as the smallest of pinholes, and the pattern thrown on a screen beyond is not a tiny circular patch of light, but a far larger pattern of concentric rings, in which light and dark rings alternate— “diffractionrings.”Fig. 1 of PlateII (p. 42) shews the pattern obtained by allowing a beam of light to pass through a pinhole on to a photographic plate. All the light which is more than a pinhole’s radius from the centre has in some way bent round the edge of the hole. Newton regarded these phenomena as evidence that his “light-corpuscles” were attracted by solid matter. He wrote: The rays of light that are in our air, in their passage near the angles of bodies, whether transparent or opaque (such as the circular and rectangular edges of coins, or of knives, or broken pieces of stone or glass), are bent or inflected round those bodies, as if they were attracted to them; and those rays which in their passage came nearest to the bodies are the most inflected, as if they were most attracted. Here again Newton was strangely anticipatory of present-day science, his supposed forces being closely analogous to the “quantum forces” of the modern wave-mechanics. But they failed to give any detailed explanation of diffraction-phenomena, and so met with no favour. In time all these and similar phenomena were adequately explained by supposing that light con¬ sists of waves, somewhat similar to those which the wind blows up on the sea, except that, instead of
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