The Physical Meaning of Time in Modern Physics

Abstract

Time is one of the most fundamental yet conceptually subtle quantities in physics. While it appears as a parameter in many equations, its physical meaning depends on operational definitions involving clocks and spacetime geometry. This article presents a comprehensive conceptual and mathematical discussion of the nature of time in modern physics. We review the transition from Newtonian absolute time to relativistic spacetime, introduce proper time as the physically measured quantity along worldlines, discuss time dilation, analyze the thermodynamic arrow of time, and address common misconceptions. The goal is to clarify what time represents in physical theory and how it is measured in practic

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