Abstract
Evans attempted to develop a classical unified field theory of gravitation and electromagnetism on the background of a spacetime obeying a Riemann-Cartan geometry. In an accompanying paper I, we analyzed this theory and summarized it in nine equations. We now propose a variational principle for a theory that implements some of the ideas that have been (imprecisely) indicated by Evans and show that it yields two field equations. The second field equation is algebraic in the torsion and we can resolve it with respect to the torsion. It turns out that for all physical cases the torsion vanishes and the first field equation, together with Evans’ unified field theory, collapses to an ordinary Einstein equation.
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Hehl, F.W., Obukhov, Y.N. An Assessment of Evans’ Unified Field Theory II. Found Phys 38, 38–46 (2008). https://doi.org/10.1007/s10701-007-9188-7
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DOI: https://doi.org/10.1007/s10701-007-9188-7