Current State

The provided preprints from the Antigravity archive (2024–2025) do not contain any papers directly addressing Mach-effect thrusters (METs) — neither experimental reports, replication studies, nor theoretical analyses of the Woodward effect or related inertia-manipulation propulsion concepts for the period 2020–2026.

Key Approaches

The closest thematically adjacent material in the archive concerns quantum vacuum and fluctuation-induced self-propulsion. Milton, Pourtolami, and Kennedy investigate whether objects out of thermal equilibrium with their blackbody environment can experience spontaneous self-propulsive forces through second-order quantum vacuum (Casimir-type) effects [AG-2024.05-941, AG-2024.11-890, AG-2025.01-1012]. These studies demonstrate that inhomogeneous bodies can acquire terminal velocities without exotic electromagnetic properties, though the predicted forces are exceedingly small and the mechanism is entirely distinct from the Mach-effect / transient mass fluctuation framework. No connection to MET experiments or Woodward's theoretical basis is made in any of these works.

Other archive entries address precision sensing and novel force detection in contexts unrelated to METs: levitated mechanical sensors for space [AG-2025.02-682, AG-2025.12-020], gravitational gradient measurements with tetrahedral spacecraft [AG-2024.04-039], proton-beam gravitational field tests at the LHC [AG-2025.04-673], fifth-force constraints from low Earth orbit [AG-2024.10-799], and warp-drive technosignature searches [AG-2024.05-558]. None of these engage with MET experimental claims or their theoretical critique.

Open Problems

Because the provided literature does not cover METs, it is not possible from these sources to characterize: (1) the current experimental thrust-to-noise figures reported by MET groups; (2) independent replication attempts or failures; (3) theoretical critiques of the conservation-law consistency of Woodward's transient mass fluctuation model; or (4) responses to null results obtained in shielded or vacuum environments.

Where to Read Next

The preprints archived here offer no direct pathway into the MET literature. Researchers should consult the *Journal of the British Interplanetary Society*, AIAA propulsion conference proceedings, and the work of Tajmar and colleagues on null-hypothesis testing of propellantless thrusters. Theoretical critiques grounded in general relativity and energy-momentum conservation have appeared in *Physical Review D* and *Classical and Quantum Gravity* outside this archive.

Caveat

The preprints provided do not cover Mach-effect thrusters, the Woodward effect, or any experimental or theoretical work directly relevant to the research question. No claims about MET experimental status or theoretical critique can be substantiated from this corpus. The review above accurately reflects the contents of the supplied archive only; any answer to the research question as posed would require a different set of sources.