X-Message-Number: 21720
Date: Wed, 07 May 2003 12:19:59 -0400
From: Francois <>
Subject: A thought experiment

Lets say that we make a nanodevice that can emulate a neuron of any type. It
has many dendrite and axon type parts that can interract with biological
neurons, reacting to and secreting the same neurotransmitters that neurons
use to send signals with each other. It can therefore communicate in the
approprite way with any living neuron. It can also communicate with other
nanodevices of its kind, but when it does this it bypasses its dendrite and
axon parts and just exchanges binary signals directly. Internally, this
device uses very conventional computer architecture to control those
dendrites and axons, running conventional computer code of the kind used in
your own computer as you read this. That code would probably have to be of
the fuzzy logic kind but it would still be very ordinary binary code, no
artificial intelligence or qbits or anything of the sort.

We inject such a nanodevice in a living functionning concious human brain.
It approaches a neuron and observes it, tracing all of its connexions with
other neurons, establishing how fast it fires, what kind of
neurotransmitters it uses, what kind of biochemical environment it lives in,
etc, etc. The nanodevice sets the variables of its program to match the
observed characteristics of the neuron. Those variable are not fixed, they
will evolve to match the neuron's own transformations as it responds to its
evironment and the brain's activity. Once this is done, the nanodevice
destroys the original neuron and takes its place. After a neuron fires,
there is a time period of a couple of milliseconds during which it is
completely unresponsive. The nanodevice waits for the neuron to fire and
then takes its place in less than this short time. As far as the other
neurons are concerned, nothing has changed. Their signals are still
received, they are still receiving the appropriate responses from the
nanodevice, all is well. As far as the human is concerned, nothing has
changed either, his brain is still working exactly as it did a few
milliseconds ago. Since the nanodevices are ordinary and relatively simple
computers without artificial intelligence, the substitution process would
probably have to be handled by an external much more powerful computer
through remote control.

Other nanodevices are injected and go through the same process. One after
the other, the biological neurons are replaces with their nanodevice
equivalent. When two nanodevices are in direct contact, they get rid of the
dendrite-axon path of communication between them and start communicating
with direct binary links. All the while, the dwindling biological neuron
population notice nothing amiss and neither does the councious human. In the
end, all the biological neurons are gone and the human's skull contains an
intricate massively parallel digital computer. The councious human is still
very much as he was before the process began, with the same thoughts,
memories, emotions, sense of self and personality, even though all of his
original brain is now gone. We could even have proceeded without telling him
and he would have absolutely no idea of what had just happened.

This thought experiment's aim is to demonstrate that conventional binary
computers can support a human mind, complete with self awareness. Proceeding
in this fashion even does away with the problem of identity between a copy
and its original. The transition from the biological to the binary realm is
smooth and seamless. At no time is the human subject "turned off", uploaded
and "turned on" again. It can even be done without him being aware of it. He
goes to a medical facility, is unknowingly injected the nanodevices during a
routine examination and goes home with his brand new digital brain without
ever noticing anything amiss, unless he has his skull X-rayed for some
reason.

Francois
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