Anomalous subdiffusion: ⟨r²⟩ ~ t^(2/d_w) with d_w = log5/log2 ≈ 2.32
Normal diffusion on Euclidean space: ⟨r²⟩ ∝ t (random walk, d_w=2). On the Sierpiński gasket, the fractal structure creates "dead ends" that slow transport:
⟨r²⟩ ∝ t^(2/d_w), d_w = log5/log2 ≈ 2.32
giving α ≈ 0.862 < 1 — subdiffusion. The walk dimension d_w encodes how tortuous paths through the fractal are. Measured via log-log slope of MSD vs time.