[lloeki]

You can still simulate it as a whole and have it scale:

- You can simulate whatever is not observed statistically and collapse to a discrete reality only when actually observed

- You can handwave away whatever is outside the observable universe since information (and thus effects) will never reach the observer

- Heck you can even handwave whatever has been observed and over time return to statistics thanks to n-body problem, n>2; it would be somewhat incorrect but no one would be able to check that it is wrong as long as it fits within a lightcone

I think that it's actually more "perfect" than simulating every atom, in the sense that it matches quantum mechanics, foregoing the intuitive model of a fully deterministic Newtonian universe that would need to be simulated "perfectly" everywhere all at once down to Planck scale.