2013/8/21 meekerdb <[email protected]> > On 8/21/2013 3:57 AM, Quentin Anciaux wrote: > > > > > 2013/8/21 meekerdb <[email protected]> > >> On 8/20/2013 5:26 AM, [email protected] wrote: >> >>> Citeren meekerdb <[email protected]>: >>> >>> On 8/16/2013 4:57 PM, [email protected] wrote: >>>> >>>>> Citeren meekerdb <[email protected]>: >>>>> >>>>> On 8/15/2013 6:18 AM, [email protected] wrote: >>>>>> >>>>>>> Citeren meekerdb <[email protected]>: >>>>>>> >>>>>>> On 8/14/2013 6:41 PM, [email protected] wrote: >>>>>>>> >>>>>>>>> I guess I don't understand that. You seem to be considering a >>>>>>>>>> simple case of amnesia - all purely classical - so I don't see how >>>>>>>>>> MWI >>>>>>>>>> enters at all. The probabilities are just ignorance uncertainty. >>>>>>>>>> You're >>>>>>>>>> still in the same branch of the MWI, you just don't remember why your >>>>>>>>>> memory was erased (although you may read about it in your diary). >>>>>>>>>> >>>>>>>>> >>>>>>>>> No, you can't say that you are in the same branch. Just because >>>>>>>>> you are in the clasical regime doesn't mean that the MWI is >>>>>>>>> irrelevant and >>>>>>>>> we can just pretend that the world is described by classical physics. >>>>>>>>> It is >>>>>>>>> only that classical physics will give the same answer as QM when >>>>>>>>> computing >>>>>>>>> probabilities. >>>>>>>>> >>>>>>>> >>>>>>>> Including the probability that I'm in the same world as before? >>>>>>>> >>>>>>>> With classical I mean a single world theory where you just compute >>>>>>> the probabilities based "ignorance". This yields the same answer as >>>>>>> assuming the MWI and then comouting the probabilities of the various >>>>>>> outcomes. >>>>>>> >>>>>>> >>>>>>>>> If what you are aware of is only described by your memory state >>>>>>>>> which can be encoded by a finite number of bits, then after a memory >>>>>>>>> resetting, the state of your memory and the environment (which >>>>>>>>> contains >>>>>>>>> also the rest of your brain and body), is of the form: >>>>>>>>> >>>>>>>> >>>>>>>> "The rest of my brain"?? Why do you suppose that some part of my >>>>>>>> brain is involved in my memories and not other parts? What about a >>>>>>>> scar or >>>>>>>> a tattoo. I don't see that "memory" is separable from the >>>>>>>> environment. In >>>>>>>> fact isn't that exactly what makes memory classical and makes the >>>>>>>> superposition you write below impossible to achieve? Your brain is a >>>>>>>> classical computer because it's not isolated from the environment. >>>>>>>> >>>>>>> >>>>>>> What matter is that the state is of the form: >>>>>>> >>>>>>> |memory_1>|environment_1> + |memory_2>|environment_2>+.. >>>>>>> >>>>>>> with the |memory_j> orthonormal and the |environment_j> orthogonal. >>>>>>> Such a completely correlated state will arise due to decoherence, the >>>>>>> probabilities which are the squared norms of the |environment_j>'s are >>>>>>> the >>>>>>> probabilities. They behave in a purely classical way due this >>>>>>> decomposition. >>>>>>> >>>>>>> The brain is never isolated from the environment; if project onto an >>>>>>> |environment_j> you always get a definite classical memory state, never >>>>>>> a >>>>>>> supperposition of different bitstrings. But it's not the case that >>>>>>> projecting onto a ddefinite memory state will always yield a definite >>>>>>> classical environment state (this is at the heart of the Wigner's >>>>>>> friend >>>>>>> thought experiment). >>>>>>> >>>>>> >>>>>> I think Wigner's friend has been overtaken by decoherence. While I >>>>>> agree with what you say above, I disagree that the |environment_i> are >>>>>> macroscopically different. I think you are making inconsistent >>>>>> assumptions: that "memory" is something that can be "reset" without >>>>>> "resetting" its physical environment and yet still holding that memory is >>>>>> classical. >>>>>> >>>>>> >>>>> The |environment_i> have to be different as they are entangled with >>>>> different memory states, precisely due to rapid decoherence. The >>>>> environment always "knows" exactly what happened. So, the assumption is >>>>> not >>>>> that the environment "doesn't know" what has been done (decoherence >>>>> implies >>>>> that the environment does know), rather that the the person whose memory >>>>> is >>>>> reset doesn't know why the memory was reset. >>>>> >>>>> So, if you have made a copy of the memory, the system files etc., >>>>> there is no problem to reboot the system later based on these copies. >>>>> Suppose that the computer is running an artificially intelligent system in >>>>> a virtual environment, but such that this virtual environment is modeled >>>>> based on real world data. This is actually quite similar to how the brain >>>>> works, what you experience is a virtual world that the brain creates, >>>>> input >>>>> from your senses is used to update this model, but in the end it's the >>>>> model of reality that you experience (which leaves quite a lot of room for >>>>> magicians to fool you). >>>>> >>>>> Then immediately after rebooting, you won't yet have any information >>>>> that is in the environment about why you decided to reboot. You then have >>>>> macroscopically different environments where the reason for rebooting is >>>>> different but where you are identical. >>>>> >>>> >>>> But that's where I disagree - not about the conclusion, but about the >>>> possibility of the premise. I don't think it's possible to erase, in the >>>> quantum sense, just your memory. Of course you can given a drug that >>>> erases short term memory and so it may be possible to create a drug that >>>> erases long term memory too, i.e. induces amnesia. But what you require is >>>> to erase long term memory in a quantum sense so that all the informational >>>> entanglements with the environment are erased too. So I don't think you >>>> can be to the "erased memory" state you need. >>>> >>>> Brent >>>> >>> >>> >>> But then, there is no problem restoring the original configuration of a >>> PC (e.g. if it has been infected by a virus, the systme may have become >>> unrecoverable, and you need to format the hard drive and install the OS). >>> If the computer where running an AI then that AI would simply be "born >>> again". >>> >>> If the state of the mulitverse were such that there are two sectors were >>> this happened with two different virusses the culprit of having to reset >>> the PC, then from the point of view of the "born again AI", which virus >>> caused the problem is not deternoned until it accesses that information. >>> >>> The born again AI is a unique state that isn't different in any of the >>> two possible histories, if not then you would still have traces of the >>> virus left behind in the system. >>> >> >> Why should it matter that it was running an AI instead of some other >> program? You seem to be saying that any reset will produce uncertainty, >> because there is some other branch of the multiverse in which there was a >> reset for a different reason. I can only understand that in the context of >> the program as a Platonic entity - so for that entity, which world it is in >> is uncertain. Is that what you're saying? >> >> Brent > > > ISTM that it is the same as FPI, to correctly predict your future after > the reset, you have to take in account all the branches where you are in > the same memory state, those branches may have different past (and of > course future), hence both side after the reset are uncertain... it's not > that you can jump on one branch or another, it means you are in all the > branches that are consistent with your memory state... > > > But it seems to me that this reset is a magical, impossible operation. If > the human brain is a classical computer then that means it's computational > state can be reset. But it also means the its physical state can't be > reset. The resetting operation itself, being a classical operation, is > irreversible because of decoherence into the environment. So the > environment has the information about the state leading up to the reset and > the reset operation. So when you say 'you' can find yourself on another > branch, it's not clear what 'you' refers to. Apparently it would have to > refer to an abstract computation (per Bruno, I guess) that happened to go > through the same state twice (due to the 'reset') in this world AND also at > least once in some other world. But if it went through that state in some > other world, there was already FPI even without the reset. Right? > > Right... Erasure or not, if MWI is true (or computationalism) and our current (memory/conscious) state is finitely describable, then FPI holds (in both direction, future and past).
Regards, Quentin > Brent > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/groups/opt_out. > -- All those moments will be lost in time, like tears in rain. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
