Existence of a maximal proper acceleration

Establish whether a universal maximal proper acceleration exists as a physically valid feature of spacetime and relativistic dynamics.

Background

The paper introduces maximal proper acceleration as a conjectured physical principle appearing in several settings, including geometric approaches to quantum mechanics, gravitational and quantum-gravity theories, quantum electrodynamics through the Schwinger acceleration scale, and certain classical electrodynamics models. Although the paper analyzes consequences of assuming such an acceleration bound—particularly the predicted reduction of the muon mean lifetime—it does not establish the underlying existence claim.

The unresolved issue concerns whether maximal proper acceleration is a genuine physical limitation rather than a model-dependent scale arising from particular theories or effective descriptions. This question motivates the comparison of several candidate acceleration scales, including those associated with high-order jet electrodynamics, Caianiello’s geometry, and the Schwinger limit.