2017 Theses Master's

A Direction of Time in Time-Symmetric Electrodynamics

Tatem, Kathleen V.

This thesis introduces a recent analytical verification which is of significance to the philosophical debate on the direction of time in the case of electromagnetic radiation. I give an overview of a the problem of the direction of time in thermodynamics, as well as how it is solved with the Past Hypothesis, a hypothesis that the macrostate of the universe at the moment of the Big Bang was an extremely low-entropy state. I also describe the standard accepted textbook solution to the radiation problem, as well as an alternative time-symmetric theory presented by Feynman and Wheeler that had historically been considered less favorable to physicists. Analytical verification supports that time-symmetric accounts of radiation such as Feynman and Wheeler's theory are needed for radiation fields to comply with energy conservation and the fundamental equations of electromagnetism. I describe two other philosophical accounts of the direction of time in radiation theory, and then argue that proposed experiments based on this recent analytical result can help us rule out some of the alternative philosophical proposals on the origin of the direction of time in radiation theory. I also suggest that if the proposed experiment does not yield the hypothesized result, physicists could move forward by modifying the fundamental laws of electrodynamics. I conclude with a suggestion for a hypothetical experiment that could potentially stop time in an isolated macroscopic system, and help determine the physical origin of the direction of time.