Re: tech: digital physics

Anders Sandberg (asa@nada.kth.se)
11 May 1999 16:30:16 +0200

Brian Atkins <brian@posthuman.com> writes:

> I don't see how the actual physical structure of the CA can
> possibly matter to us in this way. The CA might have any
> number of physical layouts or properties, but all we can see
> is the effect of it all. The cells may be programmed in such
> a way that the diagonal speeds are the same as the other speeds.
> We really can't tell how the hardware works can we?

No. But what was the issue here was the fact that the geometry of the underlying grid of the CA makes the physics in the CA nonisotropic - there are preferred directions where the speed of light is different. For example, in Game of Life information from an event at (0,0) at time zero will arrive to (100,100) at the same time as information from time zero events at all points (x,0) where 0<=x<=200. Clearly, this doesn't correspond well to our physics. 

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Anders Sandberg                                      Towards Ascension!
asa@nada.kth.se                            http://www.nada.kth.se/~asa/
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