Spacetime that is essentially void of particles would be flat - with Higgs Bosons in a particleless universe permeating evenly throughout spacetime.
With the introduction of particles, Higgs Bosons would collectively concentrate towards the particles (giving rise to particle mass - and the localised curvature of spacetime) - and give a negative curvature to relative spacetime that is devoid of particles (ie Dark energy).
Dark energy may originate from the same mechanism that gives particles mass. In that, Mass can be regarded as simply as a particle accelerating through a multidimensional space-time. Dark energy may be a property that also arises from that same multidimensional space-time imbalance.
In quantum theory, quantum information must be conserved. The entropy of a black hole is given by the equation:
S = {c³kA} / {4 h-bar G)
S = entropy c = speed of light k = Boltzmann's constant A = the surface area of the event horizon (h-bar) = the reduced Planck's Constant G = gravitational constant.
This hypothesis assumes the universe is finite and has a surface boundary; it also assumes that an increase in entropy and time (quantum information) increases the surface boundary - leading to an apparent expansion of space-time. It also predicts that during the photonic age of the universe the expansion of spacetime stops.
The ekpyrotic theory hypothesises that the big bang was created by the collision of two parallel 5 dimensional membranes. The breaking of a higher dimensional universe, transferred the relatively low energy of the higher dimension to a lower dimension, and 'intensified' the energy. This energy drove the expansion of space-time. Electromagnetism, Weak and the Strong nuclear forces would be constrained on one brane, with Gravity unconstrained and free to move through the bulk. In this revised Brane cosmology it is hypothesed that dark energy is the result of the 'expansion' of the bulk.