Does quantum field theory have a hidden spectral fingerprint?

The causal propagator encodes how quantum fields communicate across spacetime — it's the mathematical heartbeat of causality in quantum field theory. By studying its eigenvalue spectrum, the authors conjecture an asymptotic scaling law analogous to Weyl's famous result linking a drum's overtones to its shape, but now for Lorentzian (relativistic) spacetimes. If confirmed, this would give a spectral toolkit for reading off spacetime geometry from quantum field data alone.