Re: [quant-ph-0212078] What is the speed of quantum information

From: Bruno Marchal <>
Date: Wed, 12 Feb 2003 10:31:57 +0100

Gordon wrote:

>Bruno Marchal wrote:
>> David Deutsch wrote:
>> >The quantum theory of computation is the theory of all abstract tasks
>> >that can be performed by physical systems. As I just said, it is
>> >pointless to invent some other class of abstract tasks and call them
>> >'computations'.
>> BM: Unless one is foolish enough dreaming to explain what *is*
>> a physical system from the notion of natural numbers, which, in the mind
> > of some platonist, is a simpler notion.


>1.when you reject alot of others fields

Which fields do you think I reject? My feeling is that it is the
physician or cognitive scientist like Dennet who reject fields, if
not experience data.

>2.And forget about the contrdictions in your web of Belief (we all
>hold?)since birth.

Not only I don't forget it, but I keep reminding everyone of the
Godelian consistency of inconsistency. Well before my birth (and even
beyond should I say) the ideal correct machine has developped a web
of contradictory belief.

>3.Ignore the fact that it's hard to test and hard to Falsify, remeber
>our our Holodeck friend?

Please, I use our Holodeck friend to define what the computationalist
hypothesis is. And I acknowledge the impossibility of falsifying NOT-COMP.
But then I show how to falsify COMP.

>Yes once you ingore all that then yes it is simpler but where does that
>notion come from in the first place???

Good question. But at least anybody having enough introspective
power can appreciate the mystery of numbers, and making comp explicit
gives a way for explaining why this mystery is *absolutely* insoluble.
I don't see how it is possible to assert that computation must be a
physical (quantum) concept when all our physical theories first postulate
the numbers as having meaning. Deutsch assertion that computability
should be a branch of physics is a highly non standard statement, for
logicians and mathematicians. (David is well aware of this as he told
it himself in the FOR book).

>Now this dont mean my theory or anyone is fully right or wrong, but I
>dont ignore (nore does David) the rest of the Private mixture of
>Knowledge web of belief we all hold, one of those mixture or may lay
>beyond may be right?
>Even your perhaps is in a abstract sense who know but I thing it the
>negation of the negation thats the problem within your idea???

Negation of negation? I'm not sure I understand what you mean.

> >From your good friend the anit-thesis
>Gordon. ;D


Received on Wed Feb 12 2003 - 04:31:25 PST

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