Re: Quantum Time Travel

From: Jacques Mallah <>
Date: Wed, 3 May 2000 16:44:55 -0700 (PDT)

--- Russell Standish <> wrote:
> Jacques Mallah wrote:
> > Are you saying that the Sh. eq. gives a
> > measure distribution for "outcomes" of
> > "observables" even when there are no observer-
> > moments? What is that supposed to mean?

> The SE is well defined given our state of knowledge
> of Titan's surface, and one can compute a
> measure distribution of observable outcomes if an
> observer were to be present.

    You seem to be talking about a hypothetical
distribution corresponding to some particular kind of
observer for some hypothetical situation. I certainly
wouldn't call that a measure distribution associated
with the wavefunction!

> > If by "observables" you mean Hermitian
> operators, how does the Sh. eq. do the above?
> If A is your observable, x is the state your system
> is in, and y indexes the set of outcomes, the
> distribution <y|A|x> is the measure
> distribution of outcomes fro that observable.
> Surely, you know this already.

    First, telling me a formula for the measure
distribution (if there were one) doesn't answer my
question, because you didn't tell me how the Sh. eq.
gives rise to that formula. Derive it.
    Second, you need to refresh your QM. Suppose we
are looking for a measure distribution M(y), and we
assume it's the same one as the 'probability
interpretation' of QM would have us believe. If the
system is in state x, the 'probability' of y is taken
to be p(y)=|<y|x>|^2. Here we take M(y) = p(y).
    Since A|y> = y|y>, your statement was that
M(y) = y <y|x>, which is not the usual formula.

> I guess we differ here. I don't believe a
> computation can ever be conscious. Rather I believe
> the converse - a consciousness can always
> implement a computation.

    How does you belief compare with computationalism?

> > > My own preference is to talk about a quantum
> > > history, which under some
> > > (perhaps rather flaky) assumptions, could be
> > > identified with the concept of observer moment.
> >
> > What's a "quantum history"? Any relation to
> > the "consistent histories interpretation"?
> Perhaps, although I'm not familiar with this term.

    Maybe I could tell you, if first you answer the
main question of what one is.

- - - - - - -
               Jacques Mallah (
         Physicist / Many Worlder / Devil's Advocate
"I know what no one else knows" - 'Runaway Train', Soul Asylum
         My URL:

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Received on Wed May 03 2000 - 16:54:38 PDT

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