Spin is embedded in the
microscopic structure of spacetime and is likely the cause of
spacetime itself (Dirac equation, spin network [Penrose]
& spin foam [e.g., Smolin]).
In the Bohmian picture, the
internal motion associated with spin is recently shown to be responsible for the quantum
potential (Recami & Salesi , Phys. Rev. A, 57, p. 98;
Esposito , Found. Phys. Lett., 12, p. 165;
In the Hestenes picture,
the zitterbewegung associated with spin is said to be responsible for
all the quantum effects of the relativistic electron (see, Hestenes
, Found. Phys.,15, p. 63).
Some authors also expressed
the view that electron is Compton wavelength vortex and the wave function is about quantum vorticity(e.g.,
Sidharth, physics/0203079; Kiehn, http://www22.pair.com/csdc/pdf/bohmplus.pdf).