Re: tech: digital physics

From: hal@rain.org
Date: Tue May 11 1999 - 09:59:37 MDT


Mike Lorrey, <mike@lorrey.com>, writes:
> Ah, an excellent point Hal. What geometries would in fact make the
> speed of light the same in all directions? It would seem to me that it
> would only be the same in all directions if every possible point on the
> surface of a cell were equally likely to be in contact with any other
> adjacent cell, therefore we imply the uncertainty principle.....and
> quantum mechanics.

One way you can do this is by redefining the coordinate system on the
plane. Map point (x, y) inwards by a factor of sqrt(x^2 + y^2) and you
map the square at unit coordinates into a unit circle. This defines
a new metric for distance and should make velocities the same in all
directions in a CA model. You'd then have to choose a CA so that when
rigid macroscopic objects are rotated, they'd automatically change size
appropriately based on this new metric. It would be complicated but
could be done in theory. I think this is the kind of work which you'd
have to do to try to show that our universe could be a CA.

And by the way, even if the universe can be nicely modelled by a CA,
it wouldn't mean that someone is running it on their computer. It can
be modelled now by differential equations but that doesn't prove that
there is an analog computer running it somewhere. The CA model would
just be a new and (hopefully) simpler model of the underlying structure
of the universe.

Hal



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