Re: tech: digital physics

Anders Sandberg (
17 May 1999 12:24:57 +0200 writes:

> In that paper,, the authors
> emphasized the one aspect in which CAs are entirely compatible with
> relativity, which is that they are inherently local. The authors then
> claimed to have a way to show that the speed of light would be the
> same in all moving frames in their CA model, but I think they were just
> talking through their hats. (I'm surprised that a paper like this was
> published in what I have found in the past to be a very reliable forum,
> the LANL physics archive.)

Unfortunately the archive is not peer-reviewed, so anybody can send in stuff. I guess few real crackpots try to post to gr-qc eller hp-th, but the physics subsection has shown a slow increase in the number of unorthodox articles of varying quality.

> It does seem that the separation of space and time is inherent to the CA
> model. You could set up a four-dimensional CA array which might represent
> spacetime in some sense, but then what would it mean for the CA to evolve?
> You've already incorporated what we call "time" in the four dimensional
> CA. It just doesn't fit.

You could have a 4D CA representing the whole of spacetime, and then the evolution rule would correspond to a gradual refinement/convergence to a stable state which corresponds to the entire history of the universe.

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