Does every region of curved spacetime have a quantum state?

Gravity theorists usually need an infinitely large 'asymptotic' spacetime to define quantum states, but this paper proposes a way to assign a quantum state to any compact region purely from its boundary data. The recipe passes a key consistency check: the resulting entropies obey the mathematical inequalities required of any legitimate quantum system, and the von Neumann entropy matches an independent geometric formula due to Bousso and Penington. This could be a foundational step toward defining quantum gravity in finite, closed regions like the observable universe.