# n75 — the Caves attack on the active vacuum (2026-07-09)

## The blade
An active vacuum is a gain medium; gain media add noise (Caves);
added noise in the monitored sector = a decoherence floor at rest;
but the framework's crown-jewel prediction (n48) is NO floor. If the
blade lands: attraction XOR no-floor — an internal dichotomy killing
either the gravity sector or the flagship signature.

## The measurement
Clock-sector steady covariance, active (Delta = -1) vs passive
(Delta = +1) branches, same damping, same aux noise floor, g scan:
  EXCESS NOISE = 0.0000e+00. Identical to all printed digits at
  g = 0.05, 0.1, 0.2. The aux sector sits exactly at its noise floor
  in both branches.

## Why the blade misses (the mechanism, worth keeping)
The sign of gravity lives in the DISPERSIVE part of the induced
coupling (the Lamb shift, odd in Delta); the noise transferred to the
clocks lives in the ABSORPTIVE part (even in Delta). Flipping the
branch flips the force and leaves the fluctuations untouched — the
inverted-frequency mode with ordinary damping is not an amplifier of
any signal channel (no gain > 1 anywhere in the input-output map), so
Caves' added-noise bound has nothing to bite. ATTRACTION AND NO-FLOOR
COEXIST, measured.

## Honest caveat, same as ever
This is the idealized T -> 0^- inversion at the Gaussian level — the
same level where every other result of the program lives. A
microphysical pump maintaining the inversion could in principle bill
extra noise; that pump is ALSO where the Lambda candidate hides
(n74-A3). The program's two remaining local unknowns are the same
object: THE PUMP. Its microphysics is the last constructive frontier,
now carrying three questions at once: what maintains the inversion
(the sign), what it costs (Lambda), and what it leaks (the floor).

## Standing after n75
The active vacuum survives its assassination: stable (n74-A1),
gravitating with the full GR trio (n74-A2), and floor-free (n75) —
with one named organ left to build and three observables waiting on
it. The newest theory ends the audit alive, which after twenty-six
headstones is not a courtesy this program extends lightly.