Speaker
Description
We present a new gravitational framework in which the conventional conservation of the energy-momentum tensor is relaxed and replaced by a non-conservation law motivated by relativistic thermodynamics. In this approach, the exchange of energy and momentum between matter and the gravitational sector is treated as a fundamental physical effect rather than as an effective description of an unknown dark-energy component. The resulting field equations extend Einstein gravity while retaining the standard geometric description of spacetime and the usual conservation law as a limiting case.
We investigate the cosmological consequences of this non-conserved gravitational dynamics in a homogeneous and isotropic universe. The modified continuity equation introduces an additional matter–spacetime exchange term, which changes the evolution of the cosmic energy density and generates an effective contribution to the expansion dynamics. Remarkably, the resulting cosmological evolution can produce a transition from decelerated to accelerated expansion without introducing a fundamental cosmological constant or an exotic dark-energy fluid. For suitable parameters, the background evolution approaches the behavior of the standard $\Lambda$CDM model while providing a different physical interpretation of the source of late-time acceleration.
The framework therefore offers a thermodynamically motivated alternative to the conventional dark-energy picture and provides a direct connection between gravitational dynamics, energy exchange, and cosmological evolution. We discuss the corresponding expansion history and the prospects for confronting the model with observational cosmology, including distance-redshift measurements and the evolution of the Hubble parameter. The results suggest that violations of energy-momentum conservation, when consistently incorporated into gravitational thermodynamics, may provide a viable route toward understanding cosmic acceleration without requiring an independent dark-energy sector.
