Lorentz-covariant sampling theory for fields

TL;DR

This paper explores how sampling theory can be extended to Minkowski spacetime, maintaining Lorentz covariance and spacetime symmetries, which has implications for understanding the discrete or continuous nature of spacetime.

Contribution

It provides a detailed extension of sampling theory to relativistic spacetime, demonstrating how Lorentz covariance can be preserved in discrete sampling frameworks.

Findings

Sampling theory can be adapted to Minkowski spacetime.

Spacetime symmetries relate to families of sampling lattices.

Discrete sampling can preserve Lorentz covariance.

Abstract

Sampling theory is a discipline in communications engineering involved with the exact reconstruction of continuous signals from discrete sets of sample points. From a physics perspective, this is interesting in relation to the question of whether spacetime is continuous or discrete at the Planck scale, since in sampling theory we have functions which can be viewed as equivalently residing on a continuous or discrete space. Further, it is possible to formulate analogues of sampling which yield discreteness without disturbing underlying spacetime symmetries. In particular, there is a proposal for how this can be adapted for Minkowski spacetime. Here we will provide a detailed examination of the extension of sampling theory to this context. We will also discuss generally how spacetime symmetries manifest themselves in sampling theory, which at the surface seems in conflict with the fact that the discreteness of the sampling is not manifestly covariant. Specifically, we will show how the symmetry of a function space with a sampling property is equivalent to the existence of a family of possible sampling lattices related by the symmetry transformations.