Emergent MOND from Cosmological Horizon Thermodynamics: Unruh-Hawking Resonance and the Redshift Evolution of the Critical Acceleration

Abstract

The empirical success of Modified Newtonian Dynamics (MOND) contrasts sharply with its lack of a fundamental microscopic mechanism. We propose a radical conceptual breakthrough: the MOND critical acceleration a₀ is not a fundamental constant, but a macroscopic emergent phenomenon arising from the thermodynamic resonance between local quantum vacuum fluctuations and the cosmological horizon. By combining the Unruh effect with the Gibbons-Hawking temperature of the de Sitter horizon, we hypothesize that when the local acceleration approaches the cosmological scale cH₀/2π, a "thermodynamic resonance" enhances vacuum polarization, modifying the effective gravitational potential. Using purely thermodynamic arguments, we analytically derive the MOND interpolating function μ(x) from first principles. Crucially, our framework yields three novel, falsifiable predictions: (1) a specific redshift evolution a₀(z)∝H(z); (2) local suppression of the MOND effect in intense stochastic gravitational wave backgrounds; and (3) "thermodynamic hysteresis" in merging galaxy clusters. This holographic paradigm bridges quantum vacuum physics and galactic dynamics without invoking new fundamental particles.