[Fis] Quantum info[Fis] Quantum info
From: Arne Kjellman <[email protected]>
Date: Wed 21 Jun 2006 - 14:40:14 CEST
The realist's riddle and the Foundations of Information Science
It seemed Andrei in the beginning opened the door to a discussions about the foundations of science,
in particular information science:
>Any careful analysis of this situation implies immediately that the whole
project "Quantum Information" should be based on more solid foundations. We recall
that >quantum mechanics by itself is a huge building having the sand-fundament - the orthodox
Copenhagen interpretation. On one hand, there was created the >advanced mathematical
formalism (calculus of probabilities in the complex Hilbert space) giving predictions which are
supported by all existing experimental data. >On the other hand, it is still unclear why this
formalism works so well and moreover it is not clear what it really predicts, because by the
orthodox Copenhagen >interpretation (which is the conventional interpretation) quantum
mechanics is not about physical reality by itself, but about just our observations (of what?).
>Problems which were of a purely philosophic interest during one hundred years became
technological and business problems. (Yes and its seemed we for some >reason lost the
interest in the philosophic questions - but I think it is simply pushed into the background
because the realists cannot straighten out the puzzle. AK)
After this clever remarks it seems to me the list discussion has been pushed into a discussion
between realist defenders - sort of neglecting other possible points of view - which make them into
rippels on the surface of classical knowning.
To my mind these discussion can go on for ever and in vain - and science we will not proceed an inch
until the day we are prepared to accept this (simple) fact that human knowing is in principle
subjective. There are several stronger reasons but the success of Copenhagen interpretation to
reject the human possibility to attribute ontological features to the presumed reality. My claim
(and SOA's) is that no coherent definition of information is possible as long as we keep on trying
to make reference to a "reality" that is unknowable in principle. Information relates to
the speaking (modelling) knower - and what is in his mind (his experience), just as Bohr says.
However his way of reasoning does not only apply to QM - it applies to all forms of knowing.
To pinpoint the situation let us consider the realist's dilemma:
A human knower first of all needs a MODEL OF HIS MIND in order to consistently describe an
ontological reality. However he has no model - and cannot even consistently dig one out.
To contemplate this situation:
Assume I can identify a part of space-time, call it O (let it be modelled by a cube of
space-time, cloud of matter, a mathematical point or even a thing - no matter). The crucial question
is as to whether O can be said to emit a signal that tells me anything about O - i.e., some feature
(property) beside the name O I have attributed to it. The assumption that this is possible lies at
the heart of IS i.e., we therefore say that such signals contains "information." This is
the equivalent to assume O is the bearer of such eventual ontological feature and such a feature
should then, according to the objectivist (and realist) be considered a pre-"given"
feature - or independent of the individual observer observer-independent (exist prior to the
knowledge of the knower). One might then ask who this very knower is - and what is the point with
human beings to search for the ability to make a similar interpretation. But let me leave this
unsolvable question and proceed.
Let us instead ask: Is my assumtion of a pre-given feature of O correct?
In order to compute some feature (property) of this is presumed entity O I then need to know what has
happened to the signal on its way from O to my consciousness - no matter whether it is a quark,
particle, thing or even a bare state transition (assume it to be a state transition ST).
The only way for me to find out how the human apparatus of perception has influenced ST on its way to
consciousness is to "send a similar" test signal the same way through my apparatus of
perception and compare the original test signal with the received test signal (under the assumtion
that the apparatus is stable). Then and only then he can compute a model of my own perceptual
apparatus. However such an act of computing is not possible until I know the original test signal -
and this is not possible because I have no model of my perceptual apparatus. (This impossibility of
comparison is most stikingly reflected in the human monistic situation: There is only one percept!)
What I can do in this embarassing situation is to assume the test signal to be "known in
advance" i.e., pre-given. This clearly is misleading since I then assume what I want to show.
There is simply no way out if this dilemma but assuming that the features of O are pre-given - but
such an assumption is also clearly misleading - for exactly the same reason. The realist is caught
in inconsistency.
I can see no way out of this dilemma. Can you? Or maybe I am mistaken?
Arne Kj
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