Re: subjective reality

From: Bruno Marchal <>
Date: Sat, 27 Aug 2005 14:31:08 +0200

On 26 Aug 2005, at 23:48, wrote:

> [BM]
> I do think so. See Deutsch book which make clear that the MWI is
> based on comp. But it is explicit in Everett and in Wheeler
> assessment. From a strict logical point of view, ad hoc non comp
> theory of MWI can be built but it is really out of topic.
> [GK]
> That may be Deutsch's opinion (though, again, I doubt he says
> anything like that in his book) but I have read both
> Everett's thesis and both Wheeler's and DeWitt's defenses of it
> and in no way shape or form does anything like YD
> even figure in them!!!

Literally, of course. YD is just a tools for explaining what it is
"to be like an Everett memory machine". It is implicit in reducing
the quantum uncertainty to the ignorance of which branch we are in a
superposition. Mathematically it can be justified by Gleason theorem
or by Graham Hartle type of infinite "frequency" operator. See the
Preskill's course on quantum computation which makes a nice summary.

> [GK]
> Let me understand this: your aim is to derive QM from an
> hypothesis which, you know, is contradicted by QM ?!!!? Wow!

I have already answered. The current aim is to derive SWE (by which
I mean the correct geometrical-gravity extension of Schroedinger Wave
Equation) from comp. I don't expect to derive anything like SWE +
collapse (although this is not entirely excluded!).
What I have already proved is that
1) if you make the move from "SWE + collapse" to "SWE + comp", then
from purely arithmetical reasons you are forced to go the the quite
simpler theory "comp". This is the result of the UDA reasoning and
you are invited to criticize it: it presuppose some "folk-psychology"
and some passive understanding of Church thesis. See the slide of my
2004 SANE paper for a presentation is eight steps.
2) I translate that reasoning into the language of a large class of
universal machine and got more constructive description of the
physics you need (by "1)") to derive from comp. This is technically
more involved. It suppresses the need of the folk psychology.

Received on Sat Aug 27 2005 - 08:36:01 PDT

This archive was generated by hypermail 2.3.0 : Fri Feb 16 2018 - 13:20:11 PST