Minimum Viable Universe

The Minimum Viable Universe is the tile at which the Four Fundamental Constraints meet, of order the Planck cell, R★ ≈ 0.47 ℓ_P and τ★ ≈ 2 t_P: the smallest spacetime quantum that can sustain self-propagating computation and enable Null Well formation. The four bounds, from information theory (the Bekenstein bound), quantum computation (the Margolus–Levitin theorem), relativity (causal connectivity) and gravitation (the Schwarzschild radius), converge at a unique scale defining the tile; below it patterns decohere, at it genesis becomes possible, which the book reads as Wheeler's "it from bit" at a concrete threshold (Part 1.6, D.1). The Margolus–Levitin cycle time exceeds the light-crossing time by π/ln 2 ≈ 4.53 at the intersection, so it is the operative cycle. The tile is of order one Planck cell and contributes no depth: the substrate quantum ℨ is the tile reduced by s, the depth the Rupture Rule fixes (D.3), s = 2^L·f^L ≈ 2.361 × 10⁶² for L = 202, so ℨ ≈ 2.283 × 10⁻¹⁰⁶ s is read back from the Planck scale, not met by the constraints directly. The book writes R★ ≈ 0.47 ℓ_P and τ★ ≈ 2 t_P, where R★ is the tile's radius [𝕃], τ★ its cycle time [𝕋], ℓ_P the Planck length and t_P the Planck time. It connects to The Four Fundamental Constraints, The MVU Convergence, Constraint Convergence at Substrate Scale, Rupture Rule, The Dilation Depth from the Rupture Rule and Zinf.