Water-filled telescopes

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Left panel (adapted from Norton, 2007): the telescope is moving with the earth; l is the length of the tube. In the same time interval, while the light goes from the top to the bottom of the telescope, the telescope moves from the left to the same point. This is the geometry at the basis of Bradley’s formula.
Central panel: according to Boscovich, when the water is added, the geometry is the same, but the velocity is different (cw > c), and the aberration angle is smaller.
Right panel: according to Wilson, one has to take into account also the refraction of light in water; the ratio of the sinus of incidence and refraction angle is the refractive index n, cw > c and cw = c n in the corpuscular hypothesis; l’ is the path of the light in the tube, and s is the displacement of the telescope (see Pedersen, 2000). In this case the conclusion is that the aberration with the water is the same as that without it.

Elio Antonello

In the present short note we discuss the case of the thought experiments on water-filled telescopes and of their realizations during 18th and 19th century.

1. Introduction

Several authors in recent years discussed in some detail the studies of the light propagation in water made in past centuries, and the different opinions on the effective importance of such tests. In the following we will refer mainly to those works.
Let us start by recalling the main ideas about light propagation in seventeenth century.
The law of refraction was well established and accepted, but there were two different interpretations.
According to the corpuscular or emission theory, the velocity of light was larger in the denser medium …
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Written by physicsgg

January 23, 2014 at 6:20 pm

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