to those playing with the particlegenerators and fastparticlegenerators, in the size, color, weight, etc. there is an entry called 'overlife'....learn what that does and how to use it and you can literally make anything......hint: linear interpolation..
....time cannot go backwards, only forwards and always accumulates to 1....
EDIT: one overlife is tied to the PG or FPG life, the others are tied to each actual particle's life.