From: Mitchell Porter (mitchtemporarily@hotmail.com)
Date: Thu Apr 19 2001 - 04:30:26 MDT
Robert Bradbury said
>I believe a recent paper in
>Science has completely disproven the classical 'Penrosian'
>perspective in this area because the 'noise' in the mind
>far exceeds the quantum mechanical effects.
The article in question (Science, Feb. 4, 2000, 287,
No. 5454, p791) reports on a paper by Max Tegmark
(quant-ph/9907009) which I mentioned in my original message:
>There is a well-known paper (http://xxx.lanl.gov/abs/quant-ph/9907009)
>arguing that mesoscopic quantum states would rapidly decohere under
>biological conditions; there is another paper
>(http://xxx.lanl.gov/abs/quant-ph/0007020) arguing that the first paper's
>argument does not apply to quantum-*field* effects.
The second paper uses the same formulae to calculate
decoherence times for ionic crystals like table salt,
of the order of 10^-37 seconds:
"According to [these calculations], due to the very
short decoherence time, the considered crystals are
not QM systems: They do not exist as stable quantum
systems. Then one could naively conclude that they
are systems ruled by classical mechanics. Of course,
such a conclusion is wrong: It contradicts the
well known and experimentally well tested QFT
description of the crystals..."
and later:
"...as shown above, the origin of the high stability
of macroscopic quantum systems cannot be in the
QM superposition mechanism. It is in the coherent
condensation in the ground state of long range
correlation modes ... [in the case of crystals,
phonons]"
I mailed Tegmark about this paper a week ago, asking
for his opinion, so I'm hoping to hear back soon.
There's also a reply to Tegmark's paper (quant-ph/0005025)
which is being reviewed at Phys Rev E right now.
The issue is far from settled.
Robert again:
>Until you
>come up with some premise for aspects of the 'mind' that ARE *not*
>explained by Calvin's Darwinian mating/copying/selection perspective
>then, may we *please* presume that normal physics is completely
>sufficient without having to delve into the QM realm?
As I said in my last message, I don't think QM by itself
can explain the mind any more than classical physics does,
but (again, thanks to nonseparability) it is much friendlier
to straightforward realism about the unity of consciousness
than emergent-computationalist approaches like Daniel
Dennett's, which regards the self as an illusion or fiction,
a 'narrative center of gravity'.
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