Vacuum Silence in Participatory Causal Diamonds

The vacuum catastrophe is a mismatch of 123 orders of magnitude between the quantum field theory prediction for vacuum energy density and the observed cosmological constant. It remains one of the most significant unsolved problems in physics. Common approaches have invoked supersymmetry, landscape selection, vacuum energy sequestering, and unimodular gravity, but none has achieved broad consensus. This paper takes a different approach, motivated by Wheeler's participatory view of quantum mechanics, in which only irreversibly registered classical records constitute physical reality.

The Participatory Modular Hamiltonian (PMH) framework operationalises Wheeler's vision by treating the observer's causal diamond as an irreversible recording aperture for quantum cosmological fields, with the Casini–Huerta–Myers (CHM) modular Hamiltonian defining the reference state and monitored observable. A previous companion paper introduced absorbing Lindblad recording dynamics within this architecture, but its per-fluctuation trigger fires on instantaneous modular-energy variance, which is nonzero on the CHM vacuum, reproducing the vacuum catastrophe within the recording framework. The structural change introduced here is to replace this trigger with a continuous quantum measurement process that accumulates evidence against the CHM vacuum before registering an outcome.

We show that the expected evidence-production rate vanishes exactly on the CHM reference state, while the coherent excess channel that carries the programme's observational predictions survives intact. An exact decomposition of the flagged relative entropy, the Modular–Landauer Balance, establishes that the recording layer introduces no first-order obstruction to Jacobson's entanglement equilibrium, preserving consistency with general relativity. Within the Jacobson–Visser thermodynamics of causal diamonds, the vacuum energy is the one stress-energy component identified with the reference baseline and possessing no independent recording channel. Under an explicit gravitational coupling postulate (Pₑ), it is conditionally excluded from the observer's recorded gravitational equation.

In summary, this paper offers a participatory perspective on the vacuum catastrophe. It is proposed that the vacuum catastrophe may be dissolved rather than solved, under a Wheelerian approach that what is never registered as a classical record does not constitute reality and carries no gravitational weight. Limitations and open problems are discussed.