Speaker: Jörg Frauendiener (University of Otago, New Zealand)

Title: The Sagnac effect in General Relativity

Place: Building 3 meeting room

Date: 11 November 2022, 10 p.m.



The Sagnac effect can be described as the difference in travel time between two photons traveling along the same path in opposite directions. In this talk we explore the consequences of this characterisation in the context of General Relativity. We derive a general expression for this time difference in an arbitrary space-time for arbitrary paths. In general, this formula is not very useful since it involves solving a differential equation along the path. However, we also present special cases where a closed form expression for the time difference can be given. We discuss the effect in a small neighbourhood of an arbitrarily moving observer in their arbitrarily rotating reference frame. We may also discuss the special case of stationary space-times and point out the relationship between the Sagnac effect and Fizeau's `aether-drag' experiment.