Resumen:
This paper analyzes the boundary term of the Hilbert-Einstein action for an FRW metric, and
uses it to set the conditions of the Einstein’s Field Equations. By means of the energy conservation
equation, we identify a new non gravitational general relativistic effect that modifies the space-time
fabric. This effect is due to the energy density that surrounds a given space-time region, and it gives
a physical explanation to the accelerated expansion of the universe. It also explains why we have not
found any particle or fluid responsible of the dark energy and it clarifies the coincidence problem.
These explanations are achieved without assuming the existence of exotic matter of unphysical
meaning or having to modify the Einstein’s Field Equations.