Time is a continuum in which events occur in irreversible succession and at various rates.
Events move along the path of change and in the direction of the change.
Time is unidirectional, and the direction of time is forward. The forward direction of time is the result of causal interaction.
Causality is an asymmetrical, unidirectional connection between and within events in which one event influences another event along the path of change.
When a change causes a counter-change, the counter-change occurs later in time than its cause. Conversely, the cause occurs earlier in time than its effect.
An apple will fall to the ground only after it has been shaken from a tree. The apple must first be shaken from the tree before it can fall to the ground.
The progression from action to reaction, from cause to effect, is the direction of the progress of time.
Energy which changes its location in space, travels in a forward direction in time.
In general, the forward direction of time results in the buildup and breakdown of various forms of energy, and produces the perception of past and future events.
There is not past, no future; everything flows in an eternal present.
– James Joyce