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

## TL;DR

The paper clarifies that the observed effects in certain optical experiments are illusions and not evidence of Fresnel drag or relativistic phenomena, emphasizing the distinction between true light drag and visual illusions.

## Contribution

It provides a clear theoretical distinction between genuine Fresnel drag and visual illusions in optical experiments, with three proofs demonstrating the non-physical nature of the observed 'movement'.

## Key findings

- Spatial shift in experiments is an illusion, not physical movement.
- Relative velocity and spatial shift are zero in the observed effect.
- Recorded effects are due to time lag differences, unrelated to 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.