  One of the greatest challenges of science is to understand the current
accelerated expansion of the Universe. In this work, we show that by
considering the quantum nature of the gravitational field, its wavelength can
be associated with an effective Compton mass. We propose that this mass can be
interpreted as dark energy, with a Compton wavelength given by the size of the
observable Universe, implying that the dark energy varies depending on this
size. If we do so, we find that: 1.- Even without any free constant for dark
energy, the evolution of the Hubble parameter is exactly the same as for the
LCDM model, so we expect this model to have the same predictions as LCDM. 2.-
The density rate of the dark energy is $\Omega_{\Lambda}= 0.69$ which is a very
similar value as the one found by the Planck satellite $\Omega_{\Lambda}=
0.684$. 3.- The dark energy has this value because it corresponds to the actual
size of the radius of the Universe, thus the coincidence problem has a very
natural explanation. 4.-It is possible to find also a natural explanation to
why observations inferred from the local distance ladder find the value $H_0=
73$ km/s/Mpc for the Hubble constant. We show that if we take the variability
of the dark energy into account, they should measure $H_0= 67.3$ km/s/Mpc as
well. 5.-In this model the inflationary period contains a natural successful
graceful exit.
