Le 09-juin-05, à 23:12, Jonathan Colvin a écrit :

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With comp, and assuming the copies will never be copied again and are immortal, then "b". [the experiment is redescribed below]Ok, but why? Please explain your reasoning.

`It is not simple to explain, although it is a consequence of the`

`Universal Dovetailer Argument. It comes from the fact that the measure`

`of 1-uncertainty bears on all computational histories (computation as`

`seen by a first person supported by that computation), and not on the`

`computational states. A similar facts happens with QM. This is argued`

`by David Deutsch when he insists that world's stories does not`

`duplicate but does differentiate. It is also related to Isham Quantum`

`logical structure bearing on the quantum histories.`

But the basic idea is simple perhaps: Suppose I must choose between

`a) I am 3-multiplied in ten exemplars. One will get an orange juice and`

`9 will be tortured.`

`b) I am 3-multiplied in ten exemplars. One will be tortured, and 9`

`will get a glass of orange juice instead.`

`OK. Now, with comp, strictly speaking the 1-uncertainty are`

`ill-defined, indeed. Because the uncertainty bears on the maximal`

`histories. Without precision I would choose "b".`

`But if you tell me in advance that all the 9 guys in "b", who got the`

`orange juice, will merge (after artificial amnesia of the details which`

`differ in their experience), and/or if you tell me also that the one`

`who will be tortured will be 3- multiplied by 1000, after the torture,`

`this change the number of relative histories going through the 1-state`

`"orange-juice" or "tortured" in such a way that it would be better that`

`I choose "a". Obviously other multiplication events in the "future"`

`could also change this, so that to know the real probabilities, in`

`principle you must evaluate the whole histories going through the`

`states.`

`To be sure, the reasoning of Stathis is still 100% correct with comp`

`for what he want illustrate, but such probability calculus should not`

`be considered as a mean to evaluate "real probabilities". When you look`

`at the math, this can be described by conflict between local`

`information and global information. It is all but simple. Today I have`

`only "solve" the "probability 1" case, and it is enough for seeing how`

`quantum proba could be justify by just comp. But even this case leads`

`to open math questions. It is tricky in QM too.`

Oops I must go now. Sorry for having been quick, Bruno http://iridia.ulb.ac.be/~marchal/