Near a critical point, the correlation length ξ ~ |t|^{-ν} diverges. For finite systems of size L, observables depend on L/ξ: χ(t,L) = L^{γ/ν} f̃((T−Tc)L^{1/ν}). Adjusting ν and γ/ν collapses curves for different L onto one universal function.
ν (true≈1)
1.00
γ/ν (true≈1.75)
1.75
Tc (true=2.269)
2.269
Left: raw χ vs T for L=8,16,32,64 | Right: scaled collapse