Moiré patterns
'Moiré' is a French word meaning 'watery' or 'watered silk'
and has now been adopted in English. Watered silk and mohair fabric
have an appearance that is both shimmery and like the grain of wood.
That such patterns could be produced with a pair of diffraction gratings
was pointed out by Lord Rayleigh in 1874, who also mentioned that
the principle could be useful in making accurate measurements. (.
. .)
A diffraction grating is a transparency with ruled parallel lines
so close they cannot be seen with the naked eye. But if two such gratings
are superimposed, with slightly different rulings, a pattern analogous
to the beats of sound becomes entirely visible, in fact a good alternative
name for moiré patterns would be 'visible beats'. One is provoked
to conjecture that the fundamental nature of matter is based on such
a principle. Perhaps all we can observe in nature are moiré fringes produced by something analogous to diffraction gratings in
which the distances between adjacent lines are so small that there
is no method known for their direct observation, even with an electron
microscope. This suggestion would fit in well with the theory of 'winding
space', where space is assumed not to close in on itself but to just
miss, that is, instead of being a hypersphere it is a sort of hyper-helix.
Bibliography
I. Amidror: The
Theory of the Moiré Phenomenon, Kluwer Academic Publishers
(1999).
Gregory Bateson: "The Case of Beats and Moiré Phenomena." In: Mind and Nature.
Irving John Good: "Science in the Flesh." In: Jasia Reichardt (ed.):
Cybernetics, Art and Ideas (London: Studio Vista, 1971), pp. 104-106.
J. Guild: Interference Systems of Crossed Diffraction Gratings:
Theory of Moiré Fringes. London: Oxford University Press,
1956.
J. Guild: Diffraction Gratings as Measuring Scales. London:
Oxford University Press, 1960.
G. Oster and Yasunovi Nishijama: "Moiré Patterns."
Scientific American May 1963, pp. 54-63.
Lord Rayleigh: "On the manufacture and theory of diffraction
gratings." Scientific Papers 1, p. 209; Philosophical
Magazine 47 (1874), pp. 81-93, 193-204.
Online examples
and applets.
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