The Possibility of a Non-Lagrangian Theory of Gravity

General Relativity resembles a very elegant crystal glass: If we touch its principles, that is, its Lagrangian, there is a risk of breaking everything. Or, if we will, it is like a short blanket: Curing some problems creates new problems. This paper is devoted to bring to light the reasons why we pursue the possibility of a non-Lagrangian theory of gravity under the hypothesis of an extension of the original general relativity with an ansatz inspired in the fundamental principles of classical and quantum physics.

Automated summary

General Relativity is like an elegant crystal glass, delicate and easily breakable when its principles are touched upon, leading researchers to pursue non-Lagrangian theory as a way to solve existing problems while being aware of the possibility of creating new ones.