[Junior]

The universe is not losing energy. The energy is being converted into a non-useable form (heat).

[MHGinTN]

And according to entropy, that energy is dissipating as the spacetime bubble expands, thus the energy has 'more into which' to spread. Could the action of black holes, as they suck space and time into their warping gravity holes, be responsible for a sort of 'rebounding' effect that is driving accelerated expansion for the field at large?