When the Universe is Not Watched: An Information-Compression Model of Gravity and its Observable Consequences

We propose that gravity emerges from an informational process where the metric tensor is updated only when quantum measurements occur. Spacetime regions without observers evolve under a compressive prior that minimizes quantum state complexity, leading to modified Einstein equations with an extra term Cμν = -α ⟨∇_μ ∇_ν S_vN⟩ derived from the von Neumann entropy of the metric. In the weak-field, static limit, this predicts flat rotation curves with α = 7.431×10⁻⁴¹ kg⁻¹ fitted to SPARC data. We derive testable predictions: scale-dependent growth fσ₈(z) deviations >5% at k > 0.1 h/Mpc, 8-12% suppression of the matter power spectrum, weak lensing convergence deficits in voids matching Euclid DR1 sensitivity, and time-delay echoes of 10-100 μs in FRBs and gravitational waves. The model preserves general covariance, avoids ghosts, and reduces to General Relativity when α→0. This framework replaces dark matter with quantum informational dynamics and offers immediate falsification paths with current surveys.