In the parallel universe model, the wave of possibilities is something that at first sight appears magical. Let me describe its properties. First of all, it is a wave and it can be imagined to do all the things that waves do. It undulates, vibrates, and moves through space and time.
When the wave encounters a situation that is logically impossible in a single world – a single spacetime region – the wave does something analogous to the way an ocean wave behaves when it encounters two or more spaces between piers jutting out in the ocean space. The wave splits apart. One part goes off running after one possibility and the other part follows the other possibilities. Each possibility is a reality in a different world.
If those possibilities are changed by an observer or experimenter, the wave changes accordingly. Just as a wave can be split into parts and then recombined after passing through or around obstacles, the wave of possibilities can be split apart and can be merged too. Always, like the great oceans that surround us, the wave persists. ((Frederick Alan Wolf, Parallel Universe: The Search for Other Worlds, p.40, pub. A.D.1988))