A pedagogical explanation for the non-renormalizability of gravity

Abstract

We present a short and intuitive argument explaining why gravity is non-renormalizable. The argument is based on black-hole domination of the high energy spectrum of gravity and not on the standard perturbative irrelevance of the gravitational coupling. This is a pedagogical note, containing textbook material that is widely appreciated by experts and is by no means original.

Comments: 10 pages, 4 figures, Latex. V2: typos corrected, some emphasis and clarifications added