Maximum Quantum Entanglement in a Gravity-Free Universe

We investigate the persistence of quantum entanglement in a hypothetical universe devoid of gravity. Removing gravitational interactions isolates environmental decoherence as the sole limiting factor for entanglement survival. Using a simple cross-section model, we derive analytic expressions for the maximum separation distance of entangled photons and electrons in flat spacetime. We find that photons could, in principle, sustain entanglement over galactic scales, while electrons decohere much more rapidly due to stronger environmental interactions. This framework highlights the relative insignificance of gravity in most entanglement processes and provides a tractable model for exploring quantum correlations at cosmological scales.