Jesse wrote:

> The main objection that comes to my mind is that in order to plan ahead of
> time what number should be in each tape location before the armature
> begins moving and flipping bits, you need to have already done the
> computation in the regular way--so Olympia is not really computing
> anything, it's basically just a playback device for showing us a
> *recording* of what happened during the original computation. 
> I don't think Olympia contributes anything more to the measure of the
> observer-moment that was associated with the original computation, any
> more than playing a movie showing the workings of each neuron in my brain
> would contribute to the measure of the observer-moment associated with
> what my brain was doing during that time.

You have to be careful, however, that you are not maintaining that when we
perform a computation and then do it in exactly the same way again that we
can only consider the first run to be genuine. And taking note of the
machine states and tape configuration during each step of the first run does
not mean that the second run is any less of a computation. 

This aside, you are right that we need knowledge of the steps of the
original computation to construct Olympia. We could have just filmed the
steps of the original computation and played back the film, claiming that
the film is also performing a computation. I would agree that this would not
fit the bill. Information does not flow. But is it correct to say that
information does not flow in Olympia? Consider the following. Olympia's tape
configuration is causally dependent on the armature being in a certain
state; that is, being at a certain location. And because the tape is
"multiply-located", what happens at one point can affect what is happening
at another point. Furthermore, Olympia goes through as many state changes as
the original machine and the machine state has been defined without
reference to the state of the tape and vice-versa. Lastly, unlike a film,
Olympia is sensitive to counterfactuals when in the unblocked state. Do
these indicate the flow of information? I'm tempted to say yes!

Brian Scurfield

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