On Fresnel Aether Drag, `Moving' Images, and Relativity

Abstract

I show the decisive difference between genuine transverse Fresnel drag of light in a moving medium and the "spatial shift" measured with a time dependent interference pattern of light traversing a homogeneous finite medium (J. Leach et al., PRL 100, 153902 (2008)). In the latter case, the relative velocity and spatial shift are in fact zero and the `movement' is an elementary visual illusion, easily made superluminal. Three separate proofs are given for this fact. What is recorded in the experiment is just the difference between a time dependent space-fixed pattern and its time lagged version. This has no relevance to relative motion of any physical entity, Fresnel drag or relativity.