On 03 Mar 2011, at 18:39, 1Z wrote:

If you have a UDA inside a physical universe,

I guess you mean "a UD inside a physical universe".

UDA is for the UD-Argument. The Universal Dovetailer Argument.

there is real physics
(qua physicalevents)
outside it, and there is a real study of physics outside it as well.
What goes on in a
virtualised environment is not real. You could feed virtualised people
false information
about the past, but that would not be rewriting history (in the sense
of changing the real
past) and it would have not mean that the virtualissed people had some
valid kind of history qua study of the past) either, since it would not be based
on true facts.

That might be consistent in some theory. But you elude the reasoning and the questions.

Likewise, their "phsyics" would not really be phsyics
, because it would not be based on the only real phsyical reality, the
one in which
the UDA is embedded.

Sorry but in this case, it would be based on the 'real physical reality'. The UD is physically running in that universe, and by the first person indeterminacy, even if you do an experiment in the physical universe, your first person experience remains determined by the physical computations made by the physical UD. So to connect your experience with the physical reality, that physical reality has to be retrievable from the mathematics of the UD (computer science/number theory).

There is no particular reason to think that
phsyics (qua study) that is baeed
on false information counts as physics in the true sense of the term.

You always manage to use the term "true". But we cannot use that term when doing science. We put our assumptions on the table, and we reason from there. You are wrongly "using" the term "truth", like pseudo- religion wrongly use the term "God", like a sort of authoritative thing.

If "physics" *means*
the study of what is ontologically fundamental, then what is going on
in the UDA can
only be pseudo physics.

Then you have to say "no" to the doctor, because he will build a pseudo brain. The point is that once you have said "yes" to the doctor, qua computatio, you can understand that your next most probable first person state will be more related to the infinitely many third person corresponding states run by the UD than by the one single out as being the "true universe", even if that concept makes sense.

On the other hand, if "phsyics" just means
"investigation of subjective phenomenology""
then the argument goes through -- but only because that particular
definition of physics is
doing the heavy lifting. It isn't difficult to prove that physics
isn't about objective reality if
you  have started with the assumption that it *is* about subjective

I do assume there is a physical reality. I would not talk on doctor and digital brain if that was not the case. The only assumption is that a digital brain, physical and constructed from piece of matter in my neighborhood, is able to sustain my consciousness together with my current correct relative computation. I would not say yes to the doctor if this could change the frequence of observable, by me, white rabbits, for example. This means that the UD, generates the right measure of computations corresponding to my observations. Below my level of substitution, it generates all the possible continuation, and so that fuzziness should be observable, and should be the bottom level defining what I will take at first sight to be primary matter. Comp reduces the physical laws to a measure on provable (sigma_1) arithmetical propositions weighted by the proofs/computation (the arithmetical UD).

If you still don't see this, ask for clarification of the sane04 paper(*), because it seems to me that the first seven steps are rather clear, there. You have mentioned the WR. I take from this that you do understand the six first steps, don't you? The seven step follows mainly from the invariance of first person experience for change in the delays of the (virtual) 'reconstitutions'.

The eighth step is really more conceptually subtle, and the clearer presentation I have done until now is in this list in the "MGA" thread (the Movie Graph Argument). It shows that the "real concrete UD" is not needed for the reversal to occur.

Also, each time you use the term truth and real, you have to recall what is your assumption, and to relate your notion of truth to it. No one can be certain of the ultimate third person (public) truth.

What I know, because you told us, is that you assume (well, that was probably not your wording) the existence of a physical universe, being primitively physical, and made of some primary stuff, which would be ontologically existing and not made of, or reducible to, simpler entities. What I try to explain, is that if you are using this primary matter to singularize and make existing consciousness, then the primary matter AND the mind associated with it have to be non Turing emulable. Comp assumes the mind to be Turing emulable, so you better say "no" to the doctor. ... unless you realize, may be, that, after all the physical laws might be not primitive, but themselves selected by the 'consciousness- filtering' on infinities of arithmetical relations.


(*) http://iridia.ulb.ac.be/~marchal/publications/SANE2004MARCHALAbstract.html


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