Comment by drkevorkian

There are two points. You got the first one, which is controllability. The components are controllable and programmable. But second it's important to appreciate the difference between simulating 10^23 classical billiard balls with a computer (very hard, C * 10^23 work for some C) and simulating 10^23 quantum mechanical atoms (C * d^(10^23) work for some C and some d). Those numbers are very different.