Transverse-Traceless Gauge Dynamics and the Reframing of Gravitational Wave Coherence

We demonstrate that gravitational waves possess intrinsic coherence rooted in the transverse-traceless (TT) structure of spacetime perturbations. Beginning with the linearized Einstein equations, we show that TT modes propagate as gauge-invariant plane waves with stable phase relationships. Extending this framework, we quantize these modes on a nearly flat Friedmann-Robertson-Walker background and construct coherent quantum states that retain classical-like phase coherence. This dual derivation reveals that coherence is a structural feature of the gravitational field itself. Empirical support from LIGO’s GW150914 event confirms this coherence across detectors, reinforcing the theoretical prediction.