In ordinary mechanics, adding 1 particle to a system of 1000000 doesn't change a lot. I know about the sign problem in QCD, so when temperature is cold the amount of calculation diverges. My question is: when we add yet another quark to a system of 1000000 quarks, the amount of calculation increases dramatically. But it is also possible that a solution for 1000001 quarks differs dramatically from a solution for 1000000 quarks, and a system with 1000001 quarks has some new properties? Intuitively, 1 quarks should not change a lot when we already have a million. However, looking at atomic nuclei we see that most of them are really unique. So up to approx 239 * 3 = 700-800 quarks every addition changes the system dramatically. How far does it go?