You're right about the result being 60 bytes, not 20. (Getting old. Can't convert logarithm bases in my head any more :-(
But you're wrong about this:
> if each particle, at each step, made a two-way choice, that single particle could run through that 10^140 potential states in no time flat
No, each particle can compute 10^43 states per second, or 10^60 states in 10^17 seconds (10 billion years). I think that's where I got the 20 byte number. It's 20 bytes per particle, 60 for a universe of 10^80 particles computing in parallel.
So if you find you need more than 60 bytes to do anything, that just shows that you haven't properly optimized your representation ;-)
But you're wrong about this:
> if each particle, at each step, made a two-way choice, that single particle could run through that 10^140 potential states in no time flat
No, each particle can compute 10^43 states per second, or 10^60 states in 10^17 seconds (10 billion years). I think that's where I got the 20 byte number. It's 20 bytes per particle, 60 for a universe of 10^80 particles computing in parallel.
So if you find you need more than 60 bytes to do anything, that just shows that you haven't properly optimized your representation ;-)