Re: quantum computing and the brain

From: Anders Sandberg (
Date: Mon Oct 08 2001 - 06:33:04 MDT

On Sun, Oct 07, 2001 at 09:23:20PM -0700, Robert J. Bradbury wrote:
> I do not believe there has been any "proof" that a quantum computer
> can function as a Turing machine and can therefore function as
> any computer.

Well, if you start it in an eigenstate and then evolve it with hermitean
operators, you will get the expected classical results. So it seems
quantum computers include reversible computation which in turn can do
traditional computation. But from a *practical* point of view quantum
computers will likely be rather useless as classical Turing machines.
> and if you can get ballistic heat removal (which is starting to
> look possible given recent buckytube simulations), another factor
> of 10^9 or so.

How would this work?
> Now of course, a nano-brain with a qubit add-on subprocessor
> would of course be useful, particularly if your job is gathering
> intelligence information. :-;

Or database retrieval - I want to be able to search my unsorted heaps of
knowledge in O(sqrt(N)) time.
> One thing that remains to be determined is the degree to which
> the brain is "packing bits". It looks like the neurons may
> be moderately sensitive to the timing of the firing of neuronal
> pulses -- if so, there is more going on than you can account
> for by simply counting neurons. Also important is the fact
> that the brain is *not* primarily a computation engine --
> its much more of a communication engine. Each of the 40
> billion neurons can have inputs & outputs ranging from 10^3-10^5.
> And there are rumblings in the neuroscience community that the
> glial cells are doing more than providing "nutritional" support.
> Unraveling the whole system is going to be a nightmare and I'm
> very glad that people like Anders and Eliezer are the ones
> wrestling with it and not me.

You're welcome :-) The brain is messy, but I think the underlying
principles might be surprisingly simple once we get to them. Just a
feeling, borne up by a certain hubristic hypothesis my professor and I
came up with this friday... (time to don the mad scientist coat and
practice insane laughter).

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y

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