2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/187033We consider the quantum gravitational back-reaction on an initially inflating, homogeneous and isotropic universe whose topology is $T^3 \times \Re$. Although there is no secular effect at one loop, an explicit calculation shows that two-loop processes act to slow the rate of expansion by an amount which becomes non-perturbatively large at late times. By exploiting Feynman's tree theorem we show that all higher loops act in the same sense.19 pages, plain TeX, 1 Postscript file, uses psfig.sty, revised June 1996 for publication in Nuclear Physics BHigh Energy Physics - PhenomenologyAstrophysicsGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext