The Vacuum Seismograph: Resolving the 16/pi Lattice Resonance in LIGO Interferometric Noise

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is the most sensitive listening device in human history. While designed to detect transient gravitational waves, its extreme sensitivity also functions as a "Vacuum Seismograph," recording the persistent background structure of spacetime. Standard astrophysical models dismiss low-frequency stationary noise as seismic, thermal, or control loop artifacts. This paper challenges that assumption. We demonstrate that the LIGO noise floor contains a statistically significant, non-decaying harmonic series rooted in the 16/pi geometric modulus (approx. 5.09 Hz). By applying a targeted spectral audit to open-source strain data, we identify a fundamental resonance at 5.09 Hz and its first harmonic at 10.18 Hz. These peaks align precisely with the predicted refresh rate of the Kish Lattice, a discrete, pressurized vacuum grid. Key Findings: Derivation of the Vacuum Modulus (16/pi) as a geometric necessity. Identification of the "Lattice Hum" in LIGO strain data. Differentiation between instrumental artifacts and geometric constants. Appendix: Includes the full Python verification script (ligo_vacuum_seismograph.py) used to isolate the signal. This upload serves as Flagship Paper #3 of the 16Pi Initiative, establishing the direct detection of the vacuum's discrete structure.