It all depends on your system. If you’re computing the fully quantum system of a spin glass on a regular grid using an Ising Hamiltonian or something like that, it can be computed far more straightforwardly than most fully classical systems of a similar number of particles.
It also depends on the approximations you’re making. You mention the ideal gas law, but that doesn’t apply to gases sufficiently far from thermal equilibrium, or even mechanical equilibrium. If you pop a balloon in outer space, the gases will self-sort by momentum, and thus cool faster than the ideal gas law over their volume would suggest.
So, each time we learn new physics that isn’t clever approximation, new effects are being added. They will necessarily add computational complexity, unless they allow new, different approximations to be made which more than make up for that new complexity.
It all depends on your system. If you’re computing the fully quantum system of a spin glass on a regular grid using an Ising Hamiltonian or something like that, it can be computed far more straightforwardly than most fully classical systems of a similar number of particles.
It also depends on the approximations you’re making. You mention the ideal gas law, but that doesn’t apply to gases sufficiently far from thermal equilibrium, or even mechanical equilibrium. If you pop a balloon in outer space, the gases will self-sort by momentum, and thus cool faster than the ideal gas law over their volume would suggest.
So, each time we learn new physics that isn’t clever approximation, new effects are being added. They will necessarily add computational complexity, unless they allow new, different approximations to be made which more than make up for that new complexity.