What is time? - Thoughts of a physicist

Münster, Gernot

Abstract

The contribution begins by addressing the question "What is time?" with some more philosophical preliminary remarks on Kant, McTaggart's A and B series, and the distinction between phenomenological and physical time. In the following, the perspective of physics is taken. After a brief historical overview of time measurement, three topics form the focus and are discussed in detail: (1) the arrow of time, i.e., the fact that time has an inherent direction that distinguishes the past from the future, (2) the relativity of time, and (3) the relativity of simultaneity in the theory of relativity and its implications for the concept of reality.