Le 12-déc.-05, à 18:07, Tom ([EMAIL PROTECTED]) a écrit :

In response to Stathis' thought experiment, to speak of an experiment being "set up" in a certain way is to base probabilities on an "irrelevant" subset of the whole, at least if the multiverse hypothesis is true. In the Plenitude, there are an additional 10^100 copies still existing, when you say that 10^100 copies are being shut-down. Talking about these additional 10^100 copies is just as consistent as talking about the original 10^100 copies (even more consistent if you consider Bruno's statement about cul-de-sacs.

In the Plenitude, everything washes out to zero. And Bruno, I would even say that all consistent histories wash out to zero.

I am not sure why you say this.

Bruno, I've been following your posts about Kripke semantics and have done the exercises, including the one about showing that you need a symmetrical accessibility relation to have LASE.

Nice !

However, my initial reaction still is that choosing a particular modal logic is scary to me, sending up red flags about hidden assumptions that are being made in the process. But I will continue to follow you as you present your case.

Actually I do agree with you. But in the present case, that is with comp as I defined it (or much weaker assumption really) we will not to have to make a choice on the modal logics, they will be given by the interview of the lobian machine. Precisely G (and G*) will appear to be the complete and sound logic of the provable (and true) self-referential statements made by a sound or self-referentially correct machine. This is a consequence of a theorem in pure mathematics: Solovay theorem.

Then, the translation of the UDA and in particular of the 1 and 3 notions will lead to the other modal logics we need, without us adding more (hidden) assumptions than the comp one (or much weaker).

Earlier Stathis wrote:
Bruno: OK but with comp I have argued that OMs are not primitive but
are "generated", in platonia, by the Universal Dovetailer. A 3- OM is just an UD-accessible state, and the 1-OMs inherit relative probabilities from the computer science theoretical structuring of the 3-OMs.

Are OMs directly generated by the UD, or does the UD generate the
physical (apparently) universe, which leads to the evolution of conscious beings, who then give rise to OMs?

Stathis Papaioannou

It's interesting that symmetry (Bruno's requirement for LASE) has come up lately, because Stathis' question seems to be what we are all wondering. That's the bottom line of multiverse theories: Where does the symmetry breaking come from?

Actually comp put a big assymmetry at the start (the natural numbers: 0, 1, 2, 3, 4, ...), and my question for years was how to get the symmetry which apparently lives at the bottom of physics (already classical physics, still more with QM-without collapse).

 I maintain still that it can't come from the multiverse itself.

But which "multiverse"? remember that the QM, or the existence of any physical multiverse are not among the hypothesis. Indeed the UDA forces us to justify completely the appearances of a "physical" multiverse.

Even considering only consistent histories, there is no asymmetry to be found.

This astonishes me a little bit. The very notion of "history", it seems to me, is assymetrical. But then I am not sure if you are talking about the comp consistent extensions of some machine (the comp histories) or the quantum histories of Everett, Hartle, and Co. ?

I maintain that it needs to come from outside the multiverse, which is something that we cannot explain.

It certainly (with comp) needs to be explain from outside any notion of "physical multiverse". Then the truth-provability gap (capture by the modal logic G* \ G, that is the set difference between the provable self-referential statements and the true self-referential statements) will "explain" why we cannot explain that something.
I should perhaps make some summary.


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