Imagine a pendulum which at each swing puts a mark on a moving tape. This historic record is an object at every moment we look at it. We use it as a part of our model of reality. We shall refer to the marks on the tape as representing a model time . It is very much different from the real time.
Real time is such that two moments of it never coexist.
In model time the moments coexists as different objects in some space. Thus Bergson calls model time a projection of real time on space. Bergson's real time is irrreversible. The seemingly inconceivable feature of Feynman's diagrams, the movement in the direction opposite to time, is explained simply by the fact that the time of physical theories is model time, i.e. a spacial phenomenon. Real time shows up in probability theory and statistical physics.