Every day of your life, you make a thousand choices. You may go right, you may go left. Eat the salad, eat the burger. Each choice you make is only one of a number of possible choices.
You know that the choice that you make is an integral part of your universe. What you may not know is that you make all possible choices. If you choose the Burger, there is an universe in which you pick the salad. Each choice that could be made is made in some universe.
We are each of us a maker of Universes.
Each of these universes exist parallel to each other, every outcome of every event splitting the worldline to create another set of universes. Every event, from the first second of time until the last. Everything exists somewhere in the foam of universes.
This story takes place in one such universe.
It starts on an Earth which is not so different from our own, but where the Laws of Physics are very slightly different from ours, and less forgiving to the dreams of Man.
