A Thermodynamic Derivation of Cosmic Acceleration Constant

We present a derivation of a cosmic acceleration constant from thermodynamic first principles.This constant links large-scale cosmic dynamics to the entropy density, background temperature,critical mass-energy density, and characteristic length scales of the universe. The derived value provides a natural scale for late-time cosmic acceleration and galactic rotation curves without requiringdark matter or a cosmological constant. This work forms a key element of the TRG-CGR hybridgravity framework, which behaves like ΛCDM during early-time cosmic expansion, while offeringmodified dynamics driven by thermodynamic principles at late times.