>Anyway, the point isn't that classical computers are just less powerful, the point is that they're so fundamentally different that calculating quantum phenomen

>Anyway, the point isn't that classical computers are just less powerful, the point is that they're so fundamentally different that calculating quantum phenomena can become actually impossible (as in, process will not finish before the heat death of the universe) relatively quickly as the size of the problem increases. We don't know that, because not all algorithms have been invented. Furthermore, P=NP is an open problem.