Clocks and Time

TL;DR

This paper proposes a general definition of clocks, discusses their role in quantum mechanics, and emphasizes the importance of spacetime foliation for interpreting clock readings and reconstructing time.

Contribution

It introduces a comprehensive definition of clocks and analyzes their limitations in quantum contexts, highlighting the necessity of spacetime foliation for proper interpretation.

Findings

Clocks are insufficient alone to reconstruct time without spacetime foliation.

The role of clocks differs when used externally versus internally within a system.

Spacetime foliation is essential for interpreting clock readings accurately.

Abstract

A general definition of a clock is proposed, and the role of clocks in establishing temporal pre-conditions in quantum mechanical questions is critically discussed. The different status of clocks as used by theorists external to a system and as used by participant-observers within a system is emphasized. It is shown that the foliation of spacetime into instants of time is necessary to correctly interpret the readings of clocks and that clocks are thus insufficient to reconstruct time in the absence of such a foliation.