Time is the rate of change. Rate is the speed and duration of an event. All objects and events move at velocities and for durations that correspond to their changing states. In our universe, the direction of time moves forward. The cause of an event occurs before its effect. The forward direction of time may be perceived as being incremental, continuous, or both. Our brain memory tricks us into believing that there is a past and a future. Although the consequences of changing events may be observed over time, such as the gradual buildup of a mountain chain or the lifecycle of a star, the combined action of all events occurring in the universe at any given moment is nearly instantaneous. All events occur simultaneously in the present. The instantaneous moment of time in which all events occur is equal to the minimum amount of time required to cause a change.
A Collection of Writings on Nature, Science, and Art by John Holland