From: Wei Dai (weidai@weidai.com)
Date: Wed Feb 12 2003 - 16:31:08 MST
On Wed, Feb 12, 2003 at 05:34:26PM -0500, Rafal Smigrodzki wrote:
> ### What is a deterministic computer?
It's just a classical Turing machine. All real computers are subject to
hardware errors, and therefore are not deterministic. I'm assuming that
the decision maker has access to a truly deterministic computer that does
not suffer from hardware errors, or can perform deterministic computations
in his head without error.
Here's a quote from Greg Egan's "Singleton" (available at
http://www.netspace.net.au/~gregegan/MISC/SINGLETON/Singleton.html). The
AI running in the Qusp is an example of someone who can do deterministic
computations in his head.
Back in my office, I summoned up a schematic of the device I called the
Qusp: the quantum singleton processor. The Qusp would employ all the
techniques designed to shield the latest generation of quantum computers
from entanglement with their environment, but it would use them to a very
different end. A quantum computer was shielded so it could perform a
multitude of parallel calculations, without each one spawning a separate
history of its own, in which only one answer was accessible. The Qusp
would perform just a single calculation at a time, but on its way to the
unique result it would be able to pass safely through superpositions that
included any number of alternatives, without those alternatives being made
real. Cut off from the outside world during each computational step, it
would keep its temporary quantum ambivalence as private and
inconsequential as a daydream, never being forced to act out every
possibility it dared to entertain.
The Qusp would still need to interact with its environment whenever it
gathered data about the world, and that interaction would inevitably split
it into different versions. If you attached a camera to the Qusp and
pointed it at an ordinary object ? a rock, a plant, a bird ? that object
could hardly be expected to possess a single classical history, and so
neither would the combined system of Qusp plus rock, Qusp plus plant, Qusp
plus bird.
The Qusp itself, though, would never initiate the split. In a given set of
circumstances, it would only ever produce a single response. An AI running
on the Qusp could make its decisions as whimsically, or with as much
weighty deliberation as it liked, but for each distinct scenario it
confronted, in the end it would only make one choice, only follow one
course of action.
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