On 12/16/2013 12:37 AM, Bruno Marchal wrote:

On 15 Dec 2013, at 17:04, John Clark wrote:

On Sun, Dec 15, 2013 at 4:04 AM, Bruno Marchal <marc...@ulb.ac.be <mailto:marc...@ulb.ac.be>> wrote:

            >>> you know in Helsinki that you will survive and feel to be in 
only one
            city with probability one

        >> That depends, Is "You" the Helsinki Man or the Moscow Man or the 
        Man or John K Clark?

    > They are the same man, we have already discussed this

If they are all the same man then the Washington Man is the Helsinki Man, thus the report from the Moscow Man that he sees Moscow and only Moscow is insufficient information

Exactly. As I said, we can only have a 3p confirmation of the comp 1p-indeterminacy by tracking and interviewing all copies (or some reasonable sample).

to judge the quality of the prediction about which cities the Helsinki Man will see, you've got to hear what the Washington Man has to say too if you want to know if the prediction was correct;

Yes. And in the step 3 case, both confirms they see only one city, and that gives the complete information each of them have access too in the first person way. They both confirms that they were unable to predict the city with certainty.

not that the accuracy of predictions has anything to do endowing us with a sense of self. And they are NOT all the same man, they are all John K Clark but the Moscow Man is not the Washington Man.

Exact. That is the root of the indeterminacy. They are the same man, but their history have irreversibly differentiated.
We agree on all this, but this explains the 1-indeterminacy.

     > As I said you confuse "indeterminacy" (the general vague concept) with 
the many
    different sort of indeterminacy:
     1) by ignorance on initial conditions (example: the coin), that is a 3p 
     2) Turing form of indeterminacy (example: the halting problem), that is 
again a 3p
     3) quantum indeterminacy in copenhague (3p indeterminacy, if that exists)
     4) quantum indeterminacy in Everett (1p indeterminacy, which needs the 
quantum SWE
     5) computationalist 1p-indeterminacy (similar to Everett, except that it 
does not
    need to assume the SWE or Everett-QM). It is the one we get in step 3, and 
it is
    part of the derivation of physics from comp.

Only the first 3 make any sense, and even there all those peas are unnecessary.

OK. But here, contrary to what you answered many times to Quentin, you seem to agree that if your argument is valid again the comp-indeterminacy, it is valid against Everett formulation of QM.

JKC makes a big point of the complete separation of quantum worlds, although Everett didn't write about multiple worlds. Everett only considered one world and wrote about the "relative state" of the observer and the observed system. In some ways this is more fundamental because in principle the "different worlds" of MWI can interfere with one another. That they usually don't is a statistical result.

I recall you that, like Einstein and many others, I believe that "3)" is "insanity". You might be right that it is logically conceivable (perhaps---I am not even sure about that), but once we accept events without cause, we fall in the "don't ask" type of theories. As explanation, it is as bad as the God-of-the-gap.

I think that's an unfair criticism of Copenhagen. Deterministic theories just push the problem back in time. Ultimately there is either an uncaused event or an infinite past. So there is not great intellectual virtue in rejecting uncaused events. Quantum mechanics is an interesting intermediate case. It has randomness, but randomness that is strictly limited and limited in such a way that it produces the classical world at a statistical level.

Your own theory also introduces uncaused events, namely the computations of a universal dovetailer. The whole idea of "everythingism" was inspired by QM, but QM itself doesn't entail that everything happens. If you measure a variable you only get eigenvalues of that variable - not every possible value. If you measure it again you get the same eigenvalue again - not any value.

On the contrary, self-duplication explains the appearance of such indeterminacy, without adding any further assumptions.

Well, the existence of self-duplication, even via Everett, is a further 

Occam favors it. Your belief in "3)" substitutes a very simple explanation by a call to a form of built-in-non-explainable magic.

No more magic than a UD.


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