Some Remarks on Alternative (or Modified) Theories of Gravity

Abstract

A seminar given about 30 years ago by Ruben Aldrovandi motivates this text where some reflexions about constructing theories that modify General Relativity are made. Two particular cases, the Brans-Dicke and Unimodular Gravity ones, are discussed, in a quite qualitative way, showing on how they can address some of the most outstanding problems of General Relativity, specially the transplanckian physics and the cosmological constant problem.

Latex file, 14 pages. To appear in the volume "Tribute to Ruben Aldrovandi" (Editora Livraria da Física, São Paulo, 2024)