New result from the team “Quantum Gravity”, obtained by Thibaut Josset, Alejandro Perez, and Daniel Sudarsky.

We consider the possibility of reconciling metric theories of gravitation with a violation of the conservation of energy-momentum. Under some circumstances, this can be achieved in the context of unimodular gravity, and it leads to the emergence of an effective cosmological constant in Einstein’s equation. We specifically investigate two potential sources of energy nonconservation—nonunitary modifications of quantum mechanics and phenomenological models motivated by quantum gravity theories with spacetime discreteness at the Planck scale—and show that such locally negligible phenomena can nevertheless become relevant at the cosmological scale.​

See :
PRL Editors Suggestion
Physics World
Science Mag

Picture Copyright : Fragment of "dessin d’essai" by Herve Andre