Electromagnetism and time-asymmetry

TL;DR

This paper argues that Maxwell's electromagnetism, within relativity, is only well-confirmed when assuming all fields have past sources, implying a fundamental time-asymmetry in physical laws.

Contribution

It highlights the importance of source assumptions in confirming electromagnetism and suggests a lawlike time-asymmetry in the universe.

Findings

Maxwell's theory is not well-confirmed without source assumptions.

Confirmation depends on the assumption that fields have sources in their past.

There is reason to believe in an intrinsic time-asymmetry in physical laws.

Abstract

It is a commonplace to note that in a world governed by special or general relativity, an observer has access only to data within her past lightcone (if that). The significance of this for prediction, and thus for confirmation, does not however seem to have been appreciated. In this paper I show that what we regard as our most well-confirmed relativistic theory, Maxwell's theory of electromagnetism, is not at all well-confirmed in the absence of an additional assumption, the assumption that all fields have sources in their past. I conclude that we have reason to believe that there is a lawlike time-asymmetry in the world.