An Alternative Kaluza Theory Identifying 5D Momentum and Charge

Kaluza’s 1921 theory of gravity and electromagnetism using a fifth wrapped-up spatial dimension is inspiration for many modern attempts to develop new physical theories. For a number of reasons the theory is incomplete and often considered untenable. An alternative approach is presented that more fully unifies gravity and electromagnetism. Emphasis is placed on admitting important electromagnetic fields not present in Kaluza’s original theory, and on deriving a Lorentz force law. This is done by identifying 5D momentum with charge. By doing so the usual assumption of Ricci flatness for sourceless electromagnetic fields is made obsolete and replaced by the simple and physically intuitive assumption that background 5D momentum is vanishing. An electromagnetic limit is imposed by assuming a constant scalar field.