On 12 Jul 2013, at 19:18, meekerdb wrote:
On 7/12/2013 2:11 AM, Bruno Marchal wrote:
On 11 Jul 2013, at 22:14, meekerdb wrote:
On 7/11/2013 12:34 PM, Bruno Marchal wrote:
On 11 Jul 2013, at 18:46, meekerdb wrote:
On 7/10/2013 11:25 PM, Bruno Marchal wrote:
I have given the equation. I try to explain this on FOAR but it
relies on some familiarity in logic.
Normally you should know already that physics is given by a
measure on relative computational continuations, and the logic
explains already the statistical interferences.
QM is deterministic and there is only one 'computational
continuation';
?
If you measure up+down in the base {up,down}, you get two
computational continuation, unless you add a non deterministic
collapse.
No, you only get one in which the measuring device state
(including you) is entangled with the system measured.
you * (up + down) = (you * up) + (you * down),
That is a deterministic bifurcation leading to two (at least)
computational continuations, one where you see the electron in the
up state and one in which you see the electron in the down state.
But it is not a bifurcation because it can be undone by subsequent
evolution of the wave function;
OK.
which means there is only one computational continuation.
From the 3p view only.
It is only if you assume collapse of the wave function that the
evolution cannot be reversed and that is what decoherence attempts
to explain in terms of diffusing information into the environment.
But a fundamental theory of everything has no "environment".
Indeed. But we don't need the collapse, we need only that the persons
in question does not erase their memory. It is exactly like with the
FPI. The W and M persons can still fuse, if they forget which city
they are in.
That's what "entangle" means in QM without collapse.
To get two you have to treat "measurement" as some non-unitary
operator.
Not at all, I can also use the FPI. The measurement becomes a
machine interaction followed by self-reference/personal memory
access.
But here you deviate from QM and treat the individual consciousness
as something that can irreversibly bifurcate. It is essentially
Wigner's initial theory that consciousness collapses the wave
function. The only difference is you suppose both branches to exist.
If you interpret Wigner in that way, you are right. But keeping the
branches makes the process reversible, and the 3p picture deterministic.
That's the puzzle that Everett addressed by throwing out the
collapse postulate and assuming only one kind of continuation.
Since that seemed like an attractive idea the problem has become
how to explain the experience of one thing happening and another
not.
It is solved completely by the FPI. We experience one thing and
not the other for the same comp reason why we see only W (or only
M) in the WM duplication.
What is that reason? According to QM there are two systems that are
entangled with environments such that they are statistically
unlikely to recohere and hence form persistently different memories.
Like the W-person and the M-person. Fusing remains possible, even
reversibly, by dissociating or discarding memories, of course this
needs perfect isolation of those memories from the environment.
That is why Everett can use comp and remains in a purely
deterministic framework. The only problem is that Everett did not
discovered explicitly the FPI,
He explicitly postulated it of observers in QM.
Yes, that is what I say. He could have derived if from comp directly.
which occurs also in arithmetic, which would have forced him to
understand that the wave itself must be phenomenologically derived
from a measure on all computations, and not one circumscribe to any
special universal machine (like the quantum one).
I don't see how reference to a "quantum machine" is relevant. QM is
just a theory and in fact just a schema for theories; you need the
specify the Hilbert space and the Hamiltonian before you actually
have a theory.
Hamiltonians provide just different models (realities) instantiating
the QM basic axioms. A theory is just a set of axioms and rules.
Bruno
http://iridia.ulb.ac.be/~marchal/
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