There is a huge difference between Einstein's concept of ether (he was practically forced to reintroduce the ether into his general relativity) and Weyl's theory of the ether.
For Weyl, first comes the topological manifold. Then, an affine-connection is added: a world endowed with a gravitation-inertial field named by Weyl "fuhrungsfeld", guiding field. The components of the affine connection, and not those of the metric field, are taken as the field strengths of the gravitational field.
Weyl no longer has an invariant unit of length, so in order to introduce a metric at all, it is necessary to specify an arbitrary unit length at each point, to GAUGE the space, by adding a pseudo-vector field. Then, Weyl equates ψ with the potential of the electromagnetic field. What Weyl accomplished is to anticipate the Aharonov-Bohm effect by 30 years.
"The role of the metric is taken over by the wave function, and the rescaling of the metric has to be replaced
by a phase change of the wave function."
Why is there not a unified field theory at the present time?
Because virtually all mathematicians and physicists fail to notice that within a permanent magnet there are two fluxes of streams: South-Center-North AND North-Center-South.
The modern study of the magnetic field/electromagnetism ONLY includes the South to North flow.
Yet, there are TWO continuous streams of different particles.
What, then, is the nature of the SECOND flux of particles?
https://web.archive.org/web/20160203121514/http://www.electricitybook.com/magnetricity/hojo-leed.jpg"Magnetic current is the same as electric current is a wrong expression. Really it is not one current they are two currents, one current is composed of North Pole individual magnets in concentrated streams, and the other is composed of South Pole magnets in concentrated streams, and they are running one stream against the other stream in whirling, screw like fashion, and with high speed."
Modern science only studies one of these streams.
Whittaker proved that the potential consists of pairs of bidirectional longitudinal scalar waves, and that the same equation governs both gravity and magnetism.
The second flow/stream of particles IS THE GRAVITATIONAL WAVE, which has a dextrorotatory spin. Both flows/streams form the ELECTROGRAVITATIONAL FIELD.