Quantum Circuit Complexity Growth & Brownian Circuits — Brown-Susskind conjecture: the complexity C of a quantum state under random (Brownian) unitary evolution grows linearly as C ~ t for exponentially long times, then saturates at C ~ exp(S) (entropy S ~ n qubits). Random 2-local gates applied in layers form a t-design after poly(n) depth. The complexity geometry (Nielsen) identifies C with geodesic length in SU(2^n), penalizing non-local gates. Connection to AdS/CFT: black hole interior growth ↔ complexity growth (ER = EPR).