Consider the circle, infinite angles protruding from it. The very centre is the Big Bang. Each line represents a motion in time from the Big Bang. We exist on such a line so as to experience time in a certain way - forward. Time can also move backwards. Time is an equation. 4 + 3 equals 7, and 7 equals 4 + 3. Temporal linearity is only part of the equation. What really exists is infinite temporal symmetry in each direction.