  First, due to quantum mechanics, there are, in addition to  electromagnetic waves, matter waves (Materiewellen) represented by Schrödinger’s wave function \(\psi\). And Pauli and  Dirac recognized that \(\psi\) is not a scalar but a magnitude with  several components. Thus, from the point of view of the classical  field theory of matter not two but three entities would have to be  unified. Moreover, given the transformation properties of the wave  function, Weyl says it is certain that the magnitude \(\psi\) cannot be  reduced to gravitation or electromagnetism. Weyl saw clearly, that  this geometric view of matter or physics—which to a  certain extent had also motivated his earlier construction and manner of presentation of a pure infinitesimal geometry—was untenable in light of the new developments in atomic physics. 