Time comparison refers to the measurement of one event in relation to another event.
A complete time measurement includes the unit value of a single interval, and the comparison of successive intervals.
Two or more events cannot be compared completely independently of other events since they will have interacted with other systems, and the effect of this influence cannot be accounted for systematically.
The changing states of a system are measured from a fixed point external to the system, such as the angular path of the earth’s rotation which is measured in relation to the fixed position of the stars.
On the atomic scale, a high speed radiation particle may leave an observable trace defining its direction and intensity. Traces can be measured to determine the behavior of events moving at speeds too fast to be observed.
There is a limit to how precisely time can be measured for elementary particles. The uncertainty principle states that the more precisely a quantity of energy emitted by an atomic particle is measured, the less is known about the time in which it occurs. Both the behavior of an event and its duration can be measured precisely, but not at the same time.
And indeed there will be time for the yellow smoke that slides along the street rubbing its back upon the window-panes; there will be time , there will be time to prepare a face to meet the faces that you meet; there will be time to murder and create, and time for all the works and days of hands that lift and drop a question on your plate; time for you and time for me, and time yet for a hundred indecisions, and for a hundred visions and revisions, before the taking of toast and tea. – T. S. Elliot