I think there’s certainly a question people want to ask when they talk about things like Q1 and Q2, but the standard way of asking them isn’t right. If there is no magic essence of “you” zipping around from place to place in the universe, then the probability of “you” waking up in your body can only be 1.
My advice: rather than trying to hold the universe fixed and asking where “you” goes, hold the subjective information you have fixed and ask what the outside universe is like. When you walk out of the door, do you expect to see planet A or planet B? Etc.
Right, and when you do wake up, before the machine is opened and the planet you are on is revealed, you would expect to see yourself in planet A 50% of the time in scenario 1, and 33% of the time in scenario 2?
What’s confusing me is with scenario 2: say you are actually on planet A, but you don’t know it yet. Before the split, it’s the same as scenario 1, so you should expect to be 50% on planet A. But after the split, which occurs to a different copy ages away, you should expect to be 33% on planet A. When does the probability change? Or am I confusing something here?
Yes, since you don’t expect the copy of you on planet A to go anywhere, it would be paradoxical to decrease your probability that you’re on planet A.
Which is why you have a 100% chance of being on planet A. At least in the third-person, we-live-in-a-causal-universe, things-go-places sense. Sure, in the subjective, internal sense, the copy of you that’s on planet A can have a probability distribution over what’s outside their door. But in the sense physics cares about you have a 100% probability of being on planet A both before and after the split, so nothing went anywhere.
Subjectively, you always expected your estimate of what’s outside the door to change at the time of the split. It doesn’t require causal interaction at the time of the split because you’re just using information about timing. A lot like how if I know the bus schedule, my probability of the bus being near my house “acausally” changes over time—except weirder because an extra copy of you is added to the universe.
1
1
$50
$33.33
I think there’s certainly a question people want to ask when they talk about things like Q1 and Q2, but the standard way of asking them isn’t right. If there is no magic essence of “you” zipping around from place to place in the universe, then the probability of “you” waking up in your body can only be 1.
My advice: rather than trying to hold the universe fixed and asking where “you” goes, hold the subjective information you have fixed and ask what the outside universe is like. When you walk out of the door, do you expect to see planet A or planet B? Etc.
Right, and when you do wake up, before the machine is opened and the planet you are on is revealed, you would expect to see yourself in planet A 50% of the time in scenario 1, and 33% of the time in scenario 2?
What’s confusing me is with scenario 2: say you are actually on planet A, but you don’t know it yet. Before the split, it’s the same as scenario 1, so you should expect to be 50% on planet A. But after the split, which occurs to a different copy ages away, you should expect to be 33% on planet A. When does the probability change? Or am I confusing something here?
Yes, since you don’t expect the copy of you on planet A to go anywhere, it would be paradoxical to decrease your probability that you’re on planet A.
Which is why you have a 100% chance of being on planet A. At least in the third-person, we-live-in-a-causal-universe, things-go-places sense. Sure, in the subjective, internal sense, the copy of you that’s on planet A can have a probability distribution over what’s outside their door. But in the sense physics cares about you have a 100% probability of being on planet A both before and after the split, so nothing went anywhere.
Subjectively, you always expected your estimate of what’s outside the door to change at the time of the split. It doesn’t require causal interaction at the time of the split because you’re just using information about timing. A lot like how if I know the bus schedule, my probability of the bus being near my house “acausally” changes over time—except weirder because an extra copy of you is added to the universe.