Institut für Medizinische Psychologie
Goethestr. 31, D-80336 München, Germany
Einstein's attempt of unifying General relativity and electromagnetism in the late 20ies, grown out of a correspondence with E. Cartan, is revisited in differential forms language. The purpose is to show the relation between the identities derived by Cartan and Einstein and the theory of dislocations in crystalline bodies. The equivalence of Cartan's torsion and the dislocation density was discovered in the 50ies by K.Kondo and Bilby et al.. Starting from that, it is shown that two independent parts of the torsion tensor, corresponding to edge and screw dislocations, exist, and a method of visualizing torsion is presented. Furthermore, the nontrivial topology of a continuum with finite-sized topological defects will be discussed.