Spinor-tensor Theory Of Gravitation And Cosmology

The discovery of the accelerating universe requires a modification of Einstein' s theory of gravity, so that the theory will not contradict to the observation. We review some modified theories of gravity, then propose to use the spinor-tensor theory to modify the action of Einstein gravity. Assuming homogeneous and isotropic universe, we obtain a modified Friedmann equation, and the conditions for the accelerating universe .