In an infinite universe all possibilities occur. In a large universe many possibilities occur. Among the possibilities is a prior or subsequent or even simultaneous brain just like mine.
Depending on your version of the MWI, that’s actually not quite accurate.
Consider the “man at the cliff” statistical thought experiment: A man is standing at the edge of a cliff, blindfolded. At any given time, he has a 10% chance of taking a step forward (and thus falling off the cliff), and a 90% chance of taking a step backward. If that man takes an infinite number of steps, what is the probability that at some point he falls off the cliff? One may be tempted to answer: “In an infinite number of steps, all possibilities occur and thus the probability must be 1,” but that is incorrect. The actual probability that the man falls off the cliff at some point is 11.1..%
You have to be careful when tangling with infinity because there are different degrees of “infinity”. A “man on the cliff” taking an infinite number of steps is a constrained infinity. Depending on your interpretation of many-worlds, it’s likely that you’re dealing with a similarly constrained infinity. So “infinite universes” does not imply a guarantee that possibility X will occur.
That doesn’t mean X WON’T happen. It just means it’s not guaranteed.
That’s very true. In that regard the Man on the Cliff probably wasn’t the best example. It was meant to show that infinite iterations does not guarantee an infinite possibility set or that all possibilities will be realized. So in this context, the MWI doesn’t guarantee that any scenario you can envision is happening in an alternate world.
Depending on your version of the MWI, that’s actually not quite accurate.
Consider the “man at the cliff” statistical thought experiment: A man is standing at the edge of a cliff, blindfolded. At any given time, he has a 10% chance of taking a step forward (and thus falling off the cliff), and a 90% chance of taking a step backward. If that man takes an infinite number of steps, what is the probability that at some point he falls off the cliff? One may be tempted to answer: “In an infinite number of steps, all possibilities occur and thus the probability must be 1,” but that is incorrect. The actual probability that the man falls off the cliff at some point is 11.1..%
You have to be careful when tangling with infinity because there are different degrees of “infinity”. A “man on the cliff” taking an infinite number of steps is a constrained infinity. Depending on your interpretation of many-worlds, it’s likely that you’re dealing with a similarly constrained infinity. So “infinite universes” does not imply a guarantee that possibility X will occur.
That doesn’t mean X WON’T happen. It just means it’s not guaranteed.
I think MWI does guarantee that in some worlds the man will fall off the cliff.
That’s very true. In that regard the Man on the Cliff probably wasn’t the best example. It was meant to show that infinite iterations does not guarantee an infinite possibility set or that all possibilities will be realized. So in this context, the MWI doesn’t guarantee that any scenario you can envision is happening in an alternate world.