There is a theory, often used in fiction, that every time you make a decision or an event occurs, multiple universes are created, each stemming from the possible outcomes of that decision/event. So, when I decide which way to go to work, different universes are created in which slightly different Nathanaels have slightly different days based on that decision. This is quite a nice theory in fiction, as it allows us to explore the difference a decision can make (of course, fiction being what it is, the differences will always be dramatic and interesting).
However, does it actually hold up to any sort of logical scrutiny? By that, I don’t mean “are multiple universes scientifically possible” or anything like that. Frankly that’s above my paygrade, but I imagine there’s nothing stopping multiple universes existing… just as I imagine we’ll never have any way of telling if they do or don’t. No, I’m talking about the possibility that there might be different Nathanaels out there, who took different paths in life.
You see, when I decide which way I go to work, I do so based on rational decision making; there is no Nathanael who turns left because that would be stupid compared to turning right. There is no Nathanael who decided to have a prawn sandwich at lunch (subsequently got food poisoning, was at hospital when the zombie outbreak started and then saved the world from undead hordes) because a prawn sandwich was not what I fancied. Even supposedly random events, such as a coin toss, cannot split the universe in the way fiction tells us, because as soon as the coin leaves my hand it is governed by the laws of physics and although there is an equal chance of it landing on heads or tails before it is tossed, once in the air, the outcome is inevitable (unless I intervene, but that’s a conscious decision in itself).
I’m not talking about pre-determination here; I do believe in free will and that my decisions are my own. I’m simply saying that the other Nathanael in the other universe will always make exactly the same decision as me because he has exactly the same information at exactly the same timepoint. There is no Nathanael that acted on being told that one of the prettiest girls in school fancied him and so became one of the cool kids; there is no Nathanael that did a three year course instead of a four year course at university and therefore got a better grade; there is no Nathanael that failed to get a job and turned to a life crime; there is no Nathanael with a better life, there is no Nathanael with a worse life, there is just me…
I don’t know if that’s a comfort or not.