The Yield Strength of Spacetime: Deriving the Planck Luminosity as the Rupture Limit of the Einstein Tiling

We reinterpret the Planck Luminosity (Lp = c5/G) not as a theoretical abstraction, butas the physical breakdown voltage of the Axiomatic Physical Homeostasis (APH) lattice.We posit that Luminosity is the rate at which the vacuum can dissipate Associator Stress(A) via the stiffness parameter β. We demonstrate that Lp represents the critical fluxthreshold where the geometric stiffness drops to zero (β → 0) instantaneously. Above thislimit, the Einstein Tiling cannot propagate information; the domain wall shatters, resultingin a localized Big Bang event or total metric failure. Thus, the Planck Luminosity is theupper bound of the Geometric Stiffness Reactor of the universe.