> 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.
I have to admit that I do not at all care (very) much whether our universe is a CA or not. I think CAs are damn handy to write fast forcefield engines which work well both on conventional and dedicated hardware and _indespensable_ if you want to model reality with maximum speed on a nanocomputer.