Finite Gravitational Phase Space, Unitary Evolution, and the Black Hole Information Paradox in Effective Field Theory

We argue that the effective field theory (EFT) nature of four-dimensional general relativity, as established within the USMEG-EFT framework through canonical quantization, renormalization group analysis, and BRST symmetry considerations~\cite{Chishtie2025CJP,Chishtie2025PRD,Chishtie2026Symmetry}, combined with the Bekenstein entropy bound and the implications of Penrose's singularity theorems, implies a finite-dimensional physically accessible Hilbert space for gravitational degrees of freedom. Within this Hilbert space unitary evolution is guaranteed, and the Page curve follows from Page's theorem~\cite{Page1993}. We provide two explicit, verifiable calculations that ground this argument. First, combining the Bekenstein-Hawking entropy $S_{\rm BH}(M) = 4\pi G_N M^{2}/(\hbar c)\,k_{B}$ with the Hawking evaporation rate $dM/dt = -\hbar c^{4}/(15360\pi G_{N}^{2}M^{2})$, we derive the Page time at which the entanglement entropy of the radiation peaks: corresponding to $M_{\rm Page} = M_{0}/\!\sqrt{2}$. For a solar-mass black hole this gives $t_{\rm Page}(M_\odot)\approx 1.355\times 10^{67}$~yr, a concrete and parameter-free prediction of the framework. Second, using the Parikh--Wilczek mutual information and that the entropy integral from $t=0$ to $t_{\rm Page}$ equals exactly $S_{\rm BH,0}/2$, providing independent dynamical confirmation of unitarity. The framework receives observational support from LIGO-Virgo-KAGRA confirmation of exactly two graviton polarization states, a necessary structural consequence of the USMEG-EFT constraint algebra. We discuss the relationship to the island formula program and derive explicit bounds on configurational entropy consistent with holographic bounds.