Anomalous Diffusion & Subdiffusion
Beyond Brownian motion: ⟨x²⟩ ~ t^α
MSD = 2D_α t^α | α<1: subdiffusion, α>1: superdiffusion
Anomalous diffusion breaks the classical ⟨x²⟩∝t law.
Subdiffusion (α<1): particles get trapped — common in crowded biological cells, gels, and fractal media.
Superdiffusion (α>1): long jumps dominate — turbulent flows, foraging animals.
Mechanisms: Continuous-Time Random Walks (waiting time power law), fractional Brownian motion (correlated steps), Lévy flights (heavy-tail jump lengths).