# Observers' measurements of time and length in premetric electrodynamics

## TL;DR

This paper develops a generalized observer model for measuring time and length in premetric electrodynamics, extending classical relativity concepts to a broader theoretical framework that includes perturbations of Maxwell's theory.

## Contribution

It introduces a new observer measurement framework within premetric electrodynamics, enabling analysis of relativistic effects beyond standard Lorentzian geometry.

## Key findings

- Derived observer measurements for time and length in premetric electrodynamics.
- Established a method to compute relativistic effects like time dilation and length contraction.
- Applied the framework to perturbations of Maxwell electrodynamics, including the photon sector of the standard model extension.

## Abstract

The notion of observers' and their measurements is closely tied to the Lorentzian metric geometry of spacetime, which in turn has its roots in the symmetries of Maxwell's theory of electrodynamics. Modifying either the one, the other, or both ingredients to our modern understanding of physics, requires also a reformulation of the observer model used. In this presentation we will consider a generalized theory of electrodynamics, so called local and linear premetric, or area metric, electrodynamics and its corresponding spacetime structure. On this basis we will describe an observer's measurement of time and spatial length. A general algorithm how to determine observer measurements will be outlined and explicitly applied to a first order premetric perturbation of Maxwell electrodynamics. The later contains for example the photon sector of the minimal standard model extension. Having understood an observer's measurement of time and length we will derive the relativistic observables time dilation and length contraction. In the future a modern relativistic description of the classical tests of special relativity shall be performed, including a consistent observer model.