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Abstract: Galileo noted in the 16th century that the period of oscillation of apendulum is almost independent of the amplitude. However, such a pendulum isdamped by air friction. The latter may be viewed as resulting from airmolecules getting in contact with the pendulum. It follows that air friction,not only damps the oscillation, but also introduces randomness. In theso-called ``grand-mother- clock, discovered by Huygens in the 18th century,damping is compensated for, on the average, by an escapement mechanism drivenby a falling weight. The purpose of this paper is to show that such a clock is,in its idealized form, a quiet oscillator. By ``quiet- we mean that in spiteof the randomness introduced by damping, the dissipated power viewed as theoscillator output does not fluctuate slowly. Comparison is made with quietlaser oscillators discovered theoretically in 1984. Because the input powerdoes not fluctuate in both the mechanical oscillator and the quiet laseroscillator, the output power does not fluctuate at small Fourier frequencies,irrespectively of the detailed mechanisms involved.

Author: Jacques Arnaud IES, Laurent Chusseau IES, Fabrice Philippe LIRMM


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