I had an incredibly frustrating conversation this morning trying to explain the idea of quantum immortality to someone whose understanding of MWI begins and ends at pop sci fi movies. I think I've identified the main issue that I wasn't covering in enough depth (continuity of identity between near-identical realities) but I was wondering whether anyone has ever faced this problem before, and whether anyone has (or knows where to find) a canned 5 minute explanation of it.
Much like David Allen, I'm not sure this is truly the case. The path of the coin is completely determined, if you knew all starting conditions perfectly you could predict how it would end up with complete accuracy. And the universe knows all starting conditions perfectly.
Quantum fluctuations would tend to cancel each other out (much like all the air molecules in a room are never only in one corner, leaving the rest of the room in a vacuum, even though that's not strictly impossible), and thus never exert any significant pressure on the coin in any direction, and have no net impact on it's path. I would think that the coin would land on one particular side in nearly 100% of universes, with maybe the tiniest fraction containing a truly extraordinary confluence of random fluctuations all in the same direction that made it land on the other side.
I'm almost sure that it's not actually the case. I only use the example of a coin flipping because most people consider that random and it's easier than having to explain Schrodinger's Cat.