TThe standard ΛCDM model attributes cosmic accelerated expansion to dark energy, amysterious component constituting ∼ 68% of the cosmic energy budget. This leads to the“fine-tuning” problem: the vacuum energy density predicted by quantum field theory exceeds the observed value by ∼ 120 orders of magnitude. In this paper, we propose that theobserved acceleration need not be powered entirely by dark energy. Instead, a substantialfraction arises from the cosmological-scale statistical averaging of the orbital angular momentum of the largest gravitationally bound structures—galaxy clusters. Galaxy clustersacquire orbital angular momentum via tidal torques and form a dynamical equilibriumwith gravity described by the generalized virial theorem. When this equilibrium is gradually broken by cluster mass loss and inter-cluster radiation pressure, the stored angularmomentum is released, driving an effective negative pressure. Only a weak residual darkenergy is required to act as a trigger; the main driving force comes from the angularmomentum itself. In this framework, the observationally inferred equation-of-state parameter w(z) is an effective quantity that encapsulates both the weak dark energy and theangular momentum release. The model predicts a unique arch-shaped evolution of w(z),testable by upcoming surveys. A slow outward drift of planetary orbits is also predictedas a local manifestation of the same hierarchical dynamics.1Keywords: dark energy; orbital angular momentum; galaxy clusters; cosmological averaging; tidal torque theory; virial theorem.
Wang et al. (Wed,) studied this question.