In current physics, an electron is a dimensionless point. Since a point of no extent can’t physically spin, physics has given up trying to understand quantum spin in general, let alone how matter half-spins:
“We simply have to give up the idea that we can model an electron’s structure at all. How can something with no size have mass? How can something with no structure have spin?” (Oerter, 2006) p95
In quantum realism, a photon is a quantum wave that vibrates into a quantum dimension orthogonal to its polarization plane, so it has a structure that really does spin. As earlier concluded, quantum space adds three new quantum directions at every point, all at right angles to each other as well as our space (see 3.7.2).
A photon is a two-dimensional structure in quantum space that, like a paper sheet, is invisible when viewed edge-on. So horizontal filters stop horizontal but not vertically polarized light because photons polarized at right angles occupy different spaces that don’t exist to each other.
An electron is photons filling the channels of one axis so for any line of view, only half of their quantum amplitudes are visible. If one photon is 100% visible another at right angles will be 0%, for one that projects 99% there is another that projects only 1%, and so on. If only half an electron’s photons register with us, we can only measure half its spin and so say it half spins.
This also explains another interesting property of electrons. Turning an object 360 degrees in our space returns its original state but turning an electron 360 degrees only half-turns it — it takes 720 degrees of turning to return an electron to its original state. This is impossible in three dimensions but an electron in four dimensions has two planes to turn into not one. A 360 turn in one dimension only turns half its photons and so another turn is needed to turn the other half. It must always be remembered that we are 3D Flatlanders in a four-dimensional quantum reality(Abbott, 1884).