In the 5D theory with no higher dimensional matter, all matter has null geodesics in 5D.
In the 5D theory with no higher dimensional matter, all matter has null geodesics in 5D. This means that rest mass is based on the difference between the 4D velocity, which we know contracts to rest mass and the 5th dimension which must be equal to it. (This also means all matter is "lightlike" in 5D.) Charge becomes a constant of motion from the 5D geodesic equation similar to mass as the path couples to the electromagnetic vector potential.