If I commit quantum suicide 10 times and live, does my estimate of MWI being true change? It seems like it should, but on the other hand it doesn’t for an external observer with exactly the same data...
The anthropic principle gets in the way. If you play classical (i.e. non-quantum) Russian Roulette 10 times and live, you might conclude that there is some force protecting you from death. If you play classical Russian Roulette 10 times and die, you’re not in a position to conclude anything much.
Yep. Until/unless our understanding of physics improves, we can’t get any evidence for or against MWI. Our only reason for preferring it is that it sounds simple and thus should have lower prior. But it’s a weird kind of “narrative simplicity”, not mathematical (Kolmogorov) simplicity, because mathematically there’s only one quantum mechanics and no interpretations. So I wonder why people care about MWI as anything more than an (admittedly very nice) intuition pump for studying QM.
So I wonder why people care about MWI as anything more than an (admittedly very nice) intuition pump for studying QM.
MWI says (in part) that we don’t have to make wave function collapse an integral part of the mathematical formulation of quantum mechanics. Since, historically, wave function collapse has been a part of the mathematical formulation of quantum mechanics, that seems sufficient reason to care about MWI.
I think you’re equivocating on “mathematical formulation”. We want theories to predict the future. The algorithm that assigns probabilities to your future observations is the same, and equally mysterious, across all interpretations. MWI does raise the tantalizing possibility that the Born rule might not be part of basic physics—that it might somehow emerge from a universe without it—but AFAIK this isn’t settled yet.
If I commit quantum suicide 10 times and live, does my estimate of MWI being true change? It seems like it should, but on the other hand it doesn’t for an external observer with exactly the same data...
It makes no difference. You’re either throwing away Everett branches or having a chance of throwing away everything. This experiment doesn’t tell you which. You could, however, conclude that you’re a damn fool. ;)
Assuming MWI is true, I have doubts about the idea that repeated quantum suicide would prove to you that MWI is true, as many people seem to assume. It seems to me that we need to take into account the probability measure of observer moments, and at any time you should be surprised if you happen to find yourself experiencing a low-probability observer moment—just as surprised as if you had got into the observer moment in the “conventional” way of being lucky. I am not saying here that MWI is false, or that quantum suicide wouldn’t “work” (in terms of you being able to be sure of continuity) - merely that it seems to me to present an issue of putting you into observer moments which have very low measure indeed.
If you ever find yourself in an extremely low-measure observer moment, rather than having MWI or the validity of the quantum suicide idea proved to you, it may be that it gives you reason to think that you are being tricked in some way—that you are not really in such a low-measure situation. This might mean that repeated quantum suicide, if it were valid, could be a threat to your mental health—by putting you into a situation which you can’t rationally believe you are in!
Quantum suicide would only have a low probability of causing you to observe an unlikely outcome, as should any event. The overwhelmingly likely outcome is that you just die.
If I commit quantum suicide 10 times and live, does my estimate of MWI being true change? It seems like it should, but on the other hand it doesn’t for an external observer with exactly the same data...
The anthropic principle gets in the way. If you play classical (i.e. non-quantum) Russian Roulette 10 times and live, you might conclude that there is some force protecting you from death. If you play classical Russian Roulette 10 times and die, you’re not in a position to conclude anything much.
Good point, I missed that. So MWI seems to be even subjectively unconfirmable...
Yep. Until/unless our understanding of physics improves, we can’t get any evidence for or against MWI. Our only reason for preferring it is that it sounds simple and thus should have lower prior. But it’s a weird kind of “narrative simplicity”, not mathematical (Kolmogorov) simplicity, because mathematically there’s only one quantum mechanics and no interpretations. So I wonder why people care about MWI as anything more than an (admittedly very nice) intuition pump for studying QM.
MWI says (in part) that we don’t have to make wave function collapse an integral part of the mathematical formulation of quantum mechanics. Since, historically, wave function collapse has been a part of the mathematical formulation of quantum mechanics, that seems sufficient reason to care about MWI.
I think you’re equivocating on “mathematical formulation”. We want theories to predict the future. The algorithm that assigns probabilities to your future observations is the same, and equally mysterious, across all interpretations. MWI does raise the tantalizing possibility that the Born rule might not be part of basic physics—that it might somehow emerge from a universe without it—but AFAIK this isn’t settled yet.
It should be called the MWH (Hypothesis) - not the MWI (Interpretation).
See: Q16 Is many-worlds (just) an interpretation?
It makes no difference. You’re either throwing away Everett branches or having a chance of throwing away everything. This experiment doesn’t tell you which. You could, however, conclude that you’re a damn fool. ;)
Assuming MWI is true, I have doubts about the idea that repeated quantum suicide would prove to you that MWI is true, as many people seem to assume. It seems to me that we need to take into account the probability measure of observer moments, and at any time you should be surprised if you happen to find yourself experiencing a low-probability observer moment—just as surprised as if you had got into the observer moment in the “conventional” way of being lucky. I am not saying here that MWI is false, or that quantum suicide wouldn’t “work” (in terms of you being able to be sure of continuity) - merely that it seems to me to present an issue of putting you into observer moments which have very low measure indeed.
If you ever find yourself in an extremely low-measure observer moment, rather than having MWI or the validity of the quantum suicide idea proved to you, it may be that it gives you reason to think that you are being tricked in some way—that you are not really in such a low-measure situation. This might mean that repeated quantum suicide, if it were valid, could be a threat to your mental health—by putting you into a situation which you can’t rationally believe you are in!
Quantum suicide would only have a low probability of causing you to observe an unlikely outcome, as should any event. The overwhelmingly likely outcome is that you just die.