Uber-Gravity and H0 tension

Nima Khosravi (School of Astronomy Institute)

September 11, 2017

–

Abstract: Recently, the idea of taking ensemble average over gravity models has been introduced. Based on this idea, we study the ensemble average over (effectively) all the gravity models dubbing the name uber-gravity which is a fixed point in the model space. The uber-gravity has interesting universal properties, independent from the choice of basis: i) it mimics Einstein-Hilbert gravity for high-curvature regime, ii) it predicts stronger gravitational force for an intermediate-curvature regime, iii) surprisingly, for low-curvature regime, i.e. R less than R0 where R is Ricci scalar and R0 is a given scale, the Lagrangian vanishes automatically and iiii) there is a sharp transition between low- and intermediate-curvature regimes at R=R0. Finally, we will study the cosmology of this model and argue it can reduce to a cosmology model named ”either Lambda or CDM” which is even simpler than standard LCDM. This model can address H0 tension and is distinguishable from LCDM in its prediction for the perturbations.