Theoretical basis for a solution to the cosmic coincidence problem
  Following a short discussion of some unresolved issues in the standard model of cosmology (considered to be a generic LCDM model with flat geometry and an early period of inflation), an update on the current state of research regarding the problem of negative energy is provided. Arguments are then given to the effect that traditional assumptions concerning the behavior of negative-action matter give rise to violations of both the principle of relativity and the principle of inertia. An alternative set of axioms is proposed that would govern the behavior of negative-action matter if it is to be considered a viable element of physical theories upon which cosmological models are build. A simple framework, based on general relativity and the proposed axioms, is elaborated which enables the formulation of quantitative predictions concerning the interaction between positive and negative-action bodies. Based on those developments, a solution is proposed to the problem of the discrepancy between current experimental and theoretical values of vacuum energy density (in any cosmological model), which may also constitute a solution to the problem of the unexplained coincidence between the (model-dependent) experimental values of vacuum energy density and present-day, average, matter energy density. It is also shown how irreversibility naturally arises in cosmological models derived in this context. 
J.C. Lindner