The word "time" covers a dozen different meanings or, more correctly, different categories of relationship. We distinguish between mathematical time, sidereal time, solar time, local time, physical time, physiological time, psychological time. In a similar manner as local time differs from one place to another, psychological time differs from an individual to another. An hour in the life of a child is an infinitely longer time measure than in the life of an aged person, because the life-rhythm of a child goes at a much faster pace than the rhythm of an adult.

Time that we observe in nature has no autonomous existence - it is a mode of being of a concrete object. The dependence of time on the individual perceptions and on the nature of any concrete object characterizes it as a dynamic category that escapes precise definition.

The concept of mathematical time has been created to build the edifice of science; this concept maps time to a straight line, each successive instant being represented with a point.

14.1 Self-reflexivity of Time

Mathematical time has been used as a basis for spreading the commonsensical idea of time: life undergoes movement in a single linear direction that never goes back and time is considered as a characteristic of this movement. If we move with a constant speed, time is expressed through the distance we passed divided by the speed. Of course, it only looks so simple. In order to explain what “constant speed” is, we need the category of time. The commonsensical definition of time is self-reflexive: time is defined through itself. Using earth rotation, people have created a time-measuring unit. Again this creation is self-reflexive, as the category of time has been already applied when characterising the earth rotation.