Harry Erwin wrote:
>> Kevin K. <KK at _._> wrote:
>> > Harry Erwin wrote:
> >
> > > On the other hand, it has some
> > > relevance to Church's thesis, since I haven't been able to identify the
> > > mechanism of a Turing machine (or any of the alternatives) in the
> > > anatomy 8).
> >
> > You're not going to find a Turing machine in the nervous system of a
> > bat. A Turing machine is an infinite object. Any biological system of
> > nerves with binary states is a finite automata, and thus can be
> > simulated by a Turing machine. Therefore, you will never find something
> > a bat can do which a TM cannot do, and Church's thesis is unaffected.
> >
> > Kevin K.
>> Ah, but neurons do not have binary states.
I was under the impression that they do, i.e. firing or not firing.
> In fact, to define the state
> of a neuron, you have to treat it as a continuous extended object.
That doesn't prove anything. The same can be said about the logic gates
on chip. Such gates are in a condition of continuous flux due to thermal
fluctuations, noise, varying distributions of electrons etc. But these
variations have no effect on the behavior of the chip as a computational device.
> It
> gets worse when you're dealing with a collection of neurons, because you
> now need to keep track not only of the internal states of the neurons
> but also the glial cells. So we're not dealing with a finite automaton.
So you are saying that, in principle, the function of a bat brain cannot
be simulated by a digital computer, no matter how advanced? I find that
very extravagant.
