Cosmological Averaging of Orbital Angular Momentum of Galaxy Clusters A Testable Hypothesis for Cosmic Accelerated Expansion Without Dark Energy

The standard ΛCDM model attributes cosmic accelerated expansion to dark energy, amysterious component constituting ∼ 68% of the cosmic energy budget. This assumptionleads to the “fine-tuning” problem: the vacuum energy density predicted by quantumfield theory exceeds the observed value by ∼ 120 orders of magnitude. In this paper,we propose a falsifiable alternative: cosmic accelerated expansion does not require darkenergy as a physical entity. Instead, it arises from the cosmological-scale statistical averaging of the orbital angular momentum released by the largest gravitationally boundstructures—galaxy clusters. Galaxy clusters acquire orbital angular momentum via tidaltorques, forming a dynamical equilibrium with gravity as described by the generalizedvirial theorem. When this equilibrium is gradually broken by cluster mass loss and intercluster radiation pressure, the stored angular momentum is released, driving an effectivenegative pressure and the observed acceleration. Crucially, this mechanism introducesno new energy component and contributes negligible mass density, thereby circumventingthe vacuum catastrophe entirely. In this framework, dark energy is not a substance but amacroscopic manifestation of hierarchical gravitational dynamics. We define an effectiveacceleration parameter weff(z) to characterize the expansion history, which replaces the1conventional dark-energy equation of state. The model yields a unique “arch-shaped”evolution of weff(z), testable by upcoming surveys such as DESI and Euclid, as well asa slow outward drift of planetary orbits within the Solar System. We outline a roadmapfor constraining our model with existing and future data, emphasizing that the proposedmechanism is a testable hypothesis rather than a final theory.