Origin of strings

It is shown that strings result naturally from considerations of gravitation. First, a Lorentz-covariant field formulation of gravitation in flat spacetime is developed. The requirement of covariance and the existence of a potential leads to an essentially unique theory based upon a symmetric, traceless, two-index tensor. The gravitational field possesses gauge invariance described by a second-order covariant derivative defining an associated differential geometry. The concepts of parallelism and parallel transport lead to string-like constructions