The atoms of spacetime and the cosmological constant

I describe an approach which relates classical gravity to the quantum microstructure of spacetime. In this approach, the field equations arise from maximizing the density of states of the matter plus geometry. The former is identified using the thermodynamics of null surfaces. The latter arises from the existence of a zero-point length in the spacetime which associates an internal degree of freedom with each event in the spacetime, in the form of a fluctuating vector of constant norm. The density of states, as well as the resulting field equations, remain invariant under the shift n T-b(a) -> T-b(a) + (constant)delta(a)(b) (arising from the addition of a constant to the matter Lagrangian, which is a symmetry of the matter sector). The cosmological constant (Lambda) arises as an integration constant and renders the amount of cosmic information (I-c) accessible to an eternal observer finite. The relation between Lambda and I-c allows us to determine the numerical value of (Lambda) from the information content of the quantum spacetime, within the context of cosmology.(1)