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Journal of Modern Optics

The Sagnac effect and the role of simultaneity in relativity theory

Gianfranco Spavieri, G. T. Gillies, Espen Gaarder Haug

Published Feb 20, 2021• 32 citations
Publisher

Abstract

We thoroughly examine the role of absolute and relative simultaneity in the interpretation of the Sagnac effect, using an approach that allows for determining the local speed along the light path. If the local speed of light is assumed to be c over the whole closed contour, there is no agreement with the observed result. There is agreement if the local speed is c along an open section of the contour only. Thus a rigorous and coherent interpretation of the Sagnac effect favours absolute over relative simultaneity. The implications for the Lorentz transformations and synchronization by means of the Global Positioning System are considered.

DOI
10.1080/09500340.2021.1887384

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We thoroughly examine the role of absolute and relative simultaneity in the interpretation of the Sagnac effect, using an approach that allows for determining the local speed along the light path. If the local speed of light is assumed to be c over the whole closed contour, there is no agreement with the observed result. There is agreement if the local speed is c along an open section of the contour only. Thus a rigorous and coherent interpretation of the Sagnac effect favours absolute over relative simultaneity. The implications for the Lorentz transformations and synchronization by means of the Global Positioning System are considered.
In a rod of length AB =L= L=L, rotating uniformly, any two spatially separated points along the rod are connected in a way that shows analogies with the quantum entanglement of the spin of particles. This ”classical entanglement” reflects the simultaneity preset in the system, which can be used for syncing two distant clocks, one at A and the other at B. Since it differs from Einstein synchronization, this procedure can be adopted for testing the one-way light speed and Lorentz invariance. Applications to optical Sagnac effects confirm that a consistent interpretation requires the adoption of absolute versus relative simultaneity.
In a rod of length AB =L= L=L, rotating uniformly, any two spatially separated points along the rod are connected in a way that shows analogies with the quantum entanglement of the spin of particles. This ”classical entanglement” reflects the simultaneity preset in the system, which can be used for syncing two distant clocks, one at A and the other at B. Since it differs from Einstein synchronization, this procedure can be adopted for testing the one-way light speed and Lorentz invariance. Applications to optical Sagnac effects confirm that a consistent interpretation requires the adoption of absolute versus relative simultaneity.
In a rod of length AB =L= L=L, rotating uniformly, any two spatially separated points along the rod are connected in a way that shows analogies with the quantum entanglement of the spin of particles. This ”classical entanglement” reflects the simultaneity preset in the system, which can be used for syncing two distant clocks, one at A and the other at B. Since it differs from Einstein synchronization, this procedure can be adopted for testing the one-way light speed and Lorentz invariance. Applications to optical Sagnac effects confirm that a consistent interpretation requires the adoption of absolute versus relative simultaneity.
More than a century ago, M. Sagnac realized an experiment with light rays, whose results according to him invalidated the theory of Relativity and validated the hypothesis of the Aether. This hypothesis of the ether was not retained by the scientific community, and relativistic explanations were given to the results of the Sagnac experiment. But these relativistic explanations remain open to criticism because they are various and because the prediction may differ depending on whether the observer’s frame of reference is at rest or in motion. The neo-Newtonian mechanics proposes a new explanation which leads to demonstrate the formula with P the light path. In order to verify this new interpretation, it is proposed to do again the Sagnac experiment with a slightly different light path, a square-shaped path. The results should be at least 30% lower than those predicted by the theory of Relativity. In which case, the relativistic explanation would be questioned.
This paper constitutes a background to the paper 'Quantum mechanics as space-time statistical mechanics?', arXiv:quant-ph/0501133, presented previously by the author. But it is also a free-standing and self-contained paper. The purpose of this paper is to give the reader an increased and a deeper understanding of the special theory of relativity, and the ideas lying behind the above mentioned paper. We will here consider, discuss, define, analyse, and explain things such as, e.g., the constancy of the speed of light, synchronization, simultaneity, absolute simultaneity, absolute space and time, the ether, and spacetime. Albert Einstein's original version of the special theory of relativity is fundamentally an operational theory, free from interpretation. But the old Lorentzian interpretation and the standard spacetime interpretation of the special theory of relativity will also be considered. This paper also discusses and analyses aspects of the philosophy of science that in my opinion are relevant for an understanding of the special theory of relativity.