[Oh you have no idea how bad it was. He was dragged to a club once..!]
Well, since we've already brushed on the many-worlds theory... [He pulls out a paper with a hastily scribbled visual representation of how he believes Marina works. You can probably tell he whipped that up just now, for her benefit.]
Are you familiar with Schrödinger's cat? It's a thought experiment usually illustrating the interpretation of quantum mechanics applied to every day objects. Basically, the idea is that you have a cat in a box, along with a flask containing a poison and a radioactive source. If an internal Geiger counter detects radiation, then the flask is shattered and the poison is released, killing the cat.
Now, the many-worlds theory interpretation of this thought experiment states that when the box is open, the cat is simultaneously dead and alive. It's up to the observer to "entangle" with one of the possible realities, thus making it the primary timeline. Does that make sense?