Le 09-juin-05, à 23:12, Jonathan Colvin a écrit :
>>
>> 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/
Received on Fri Jun 10 2005 - 10:53:10 PDT