2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/216202Reduced phase space formulation of CGHS model of 2d dilaton gravity is studied in en extrinsic time gauge. The corresponding Hamiltonian can be promoted into a Hermitian operator acting in the physical Hilbert space, implying a unitary evolution for the system. Consequences for the black hole physics are discussed. In particular, this manifestly unitary theory rules out the Hawking scenario for the endpoint of the black hole evaporation process.12 pages, LaTex file, Imperial-TP/92-93/8 and QMW/PH/92/16High Energy Physics - TheoryGeneral Relativity and Quantum Cosmologytext