Quantum gravity: the Inverse problem
  Quantizing the gravitational field described by General relativity being a notorious difficult, unsolved and maybe meaningless problem I use in this essay a different strategy: I consider a linear theory in the framework of Special relativity where the potentials are the components of four linear forms. General relativity and other similar covariant non linear theories can be formulated in this way. The theory that I propose is Lorentz invariant, linear, simple, and can be quantized following similar steps to those that led to quantum electrodynamics. 
Ll. Bel
physics.gen-ph