= 27d567bc2d48d9f40e9ccc20ea370b15)
David_Allen comments on A note on the description complexity of physical theories - Less Wrong
You are viewing a comment permalink. View the original post to see all comments and the full post content.
= 783df68a0f980790206b9ea87794c5b6)
Loading…= b715d02e85f7b3b4ae65ca3d3e450868)
Subscribe to RSS Feed
Powered by Reddit
= f037147d6e6c911a85753b9abdedda8d)
You are viewing a comment permalink. View the original post to see all comments and the full post content.
Comments (177)
That only provides evidence that you are determinedly suicidal and that you will eventually succeed.
But I'd have fun with my reality-steering anthropic superpowers in the meantime.
One of you would. The huge number of other diverging yous would run into an unpleasant surprise sooner or later.
No. You're comparing the likelihood of 2 hypothesis. The observation that you survived 1000 good suicide attempts is much more likely under MWI than under Copenhagen. Then you flip it around using Bayes' rule, and believe in MWI.
But other Bayesians around you should not agree with you. This is a case where Bayesians should agree to disagree.
First, not to be nit-picky but MWI != QI. Second, if your suicide attempts are well documented the branch in which you survived would be populated by Bayesians who agreed with you, no?
The Bayesians wouldn't agree with you, because the observation that you survived all those suicide attempts is, to them, equally likely under MWI or Copenhagen.
Flip a quantum coin.
Isn't that like saying "Under MWI, the observation that the coin came up heads, and the observation that it came up tails, both have probability of 1"?
The observation that I survive 1000 good suicide attempts has a probability of 1, but only if I condition on my being capable of making any observation at all (i.e. alive). In which case it's the same under Copenhagen.
The observation is that you're alive. If the Quantum Immortality hypothesis is true you will continue making that observation after an arbitrary number of good suicide attempts. The probability that you will continue making that observation if Quantum Immortality is false is much smaller than one.
The probability that there exists an Everett branch in which I continue making that observation is 1. I'm not sure if jumping straight to subjective experience from that is justified:
If P(I survive|MWI) = 1, and P(I survive|Copenhagen) = p, then what is the rest of that probability mass in Copenhagen interpretation? Why is P(~(I survive)|Copenhagen) = 1-p and what does it really describe? It seems to me that calling it "I don't make any observation" is jumping from subjective experiences back to objective. This looks like a confusion of levels.
ETA: And, of course, the problem with "anthropic probabilities" gets even harder when you consider copies and merging, simulations, Tegmark level 4, and Boltzmann brains (The Anthropic Trilemma). I'm not sure if there even is a general solution. But I strongly suspect that "you can prove MWI by quantum suicide" is an incorrect usage of probabilities.
It even depends on philosophy. Specifically on whether following equality holds.
I survive = There (not necessarily in our universe) exists someone who remembers everything I remember now plus failed suicide I'm going to conduct now.
or
I survive = There exists someone who don't remember everything I remember now, but he acts as I would acted if I remember what he remembers. (I'm not sure whether I correctly expressed subjunctive mood)
First, I'm gonna clarify some terms to make this more precise. Let Y be a person psychologically continuous with your present self. P(there is some Y that observes surviving a suicide attempt|Quantum immortality) = 1. Note MWI != QI. But QI entails MWI. P(there is some Y that observes surviving a suicide attempt| ~QI) = p.
It follows from this that P(~(there is some Y that observes surviving a suicide attempt)|~QI) = 1-p.
I don't see a confusion of levels (whatever that means).
I don't know if this is the point you meant to make but the existence of these other hypotheses that could imply anthropic immortality definitely does get in the way of providing evidence in favor of Many Worlds through suicide. Surviving increases the probability of all of those hypotheses (to different extents but not really enough to distinguish them).
I still see a problem here. Substitute quantum suicide -> quantum coinflip, and surviving a suicide attempt -> observing the coin turning up heads.
Now we have P(there is some Y that observes coin falling heads|MWI) = 1, and P(there is some Y that observes coin falling heads|Copenhagen) = p.
So any specific outcome of a quantum event would be evidence in favor of MWI.
I think that works actually. If you observe 30 quantum heads in a row you have strong evidence in favor of MWI. The quantum suicide thing is just a way of increasing the proportion of future you's that have this information.
But then if I observed any string of 30 outcomes I would have strong evidence for MWI (if the coin is fair, "p" for any specific string would be 2^-30).
You have to specify a particular string to look for before you do the experiment.
The reason why this doesn't work (for coins) is that (when MWI is true) A="my observation is heads" implies B="some Y observes heads", but not the other way around. So P(B|A)=1, but P(A|B) = p, and after plugging that into the Bayes formula we have P(MWI|A) = P(Copenhagen|A).
Can you translate that to the quantum suicide case?
I have no theories about what you're thinking when you say that.
Either you condition the observation (of surviving 1000 attempts) on the observer existing, and you have 1 in both cases, or you don't condition it on the observer and you have p^-1000 in both cases. You can't have it both ways.