X-Message-Number: 21186
From: "michaelprice" <>
References: <>
Subject: Feinberg's Principle.
Date: Sun, 16 Feb 2003 21:38:46 -0000

Donaldson says I'm "wrong on both counts".  Evidently he hasn't
noticed that we're saying the same thing on count1.  Compare:

Count1: Decoherence, low temperatures, environmental shielding, ....
> As for getting a quantum device with enough processors to
> perform significant computations, that is a hard problem. The
> problem is that the more processors you have, the harder it is
> to keep the wave function from collapsing before you get your
> answer. Yes, low temperatures and other kinds of systems
> have been suggested, but the problem still turns out to be hard.
> That [decoherence] would only be a practical problem, so
> solvable with enough time and effort.
i.e. it is a hard but not insolvable problem.

I should have thought that a cryonicist, of all people, should be acutely
aware of the difference between insolvable in principle and insolvable in
Gerald Feinberg. Physics and Life Prolongation Physics Today Vol 19 #11
45 (1966). "A good approximation for such [technological] predictions is to
assume that everything will be accomplished that does not violate known
fundamental laws of science as well as many things that do violate these
Eliminating decoherence or noise below any level does not violate
the laws of physics.

Count2: Extracting the information from a quantum computer.
Here we do differ.  I have explained why Bucksbaum's quantum
computer doesn't work.  I suspect this is a generic problem
with all quantum computers.

Michael C Price

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