Polarization is the property of a transverse wave that describes its vibration direction, so that light can polarize suggests that it is a wave. But if a filter that blocks a ray of polarized light is turned a bit, a few photons get through at full strength, and the filter angle decides how many photons do that. Yet turning an obstacle that blocks wave should weaken it as a whole, not let some waves through and others not, which is more how particles behave. Light is sometimes like a wave and sometimes like a particle, but why?
The answer lies in the nature of quantum spin. If this spin is real, it should have a:
a. Rotation axis. Around which the spin occurs, and a
b. Rotation plane. In which the spin rotation occurs.
How then does a photon spin? Let us suppose that it spins on its movement axis, as a bullet does, so it rotates into all the planes that cut its movement axis (Figure 3.19). Oddly enough, this spin doesn’t alter its polarization because its vibration occurs outside our space.
To understand this, consider a book sitting on its edge on a table with some height. If the book now spins in the rotation plane of the table, its height doesn’t change because it is at right angles to table. Likewise, if the table is our space, spinning a photon within in our space doesn’t change its transverse vibration height. Hence, a photon spinning in our space, as assumed, doesn’t change its polarization because its vibration direction is unaffected (Note 1). A photon can spin in our space around its movement axis without changing its polarization plane.
Now consider turning a filter that blocks light polarized one way. As it turns, more and more light gets through until eventually all the light does. Why then does turning a filter have an effect but turning a photon has no effect? In above example, the book represented a photon moving in a given direction across the table surface, whose vibration amplitude was the book’s height. Spinning the book then didn’t alter either its height or its movement direction. Now if the filter is like a wall that stops the photon moving on the table, turning it will then block the photon less because it is a wave. Turning a filter is like turning a wall on the table to obstruct a wave less (Note 2), while turning the photon in our space doesn’t alter its amplitude or direction. Of course it isn’t that simple, as in Chapter 4, matter fills many quantum directions not one, but the principle still applies.
Why then do some photons pass entirely through a filter on an angle? Again, it is because a physical event is an all-or-nothing affair. The filter reduces the probability that instances get through, but if one is detected, the entire photon restarts there. By the same logic, what passes through the filter is also an entire photon. A photon then travels like a wave because it is a wave, but is detected like a particle because processing always restarts completely.
Note 1. Let the photon’s wave amplitude be in a direction Q, at right angles to its polarization plane XY. Now if the photon spins in the plane YZ, this swaps its Y and Z values but leaves Q unchanged, as it is at right angles to that spin. It follows that a photon can spin around its movement axis X without altering its amplitude vibration, and hence its polarization plane.
Note 2. If Q is the quantum amplitude it reduces as Q.Cos(q°), where q° is the angle between that amplitude and the filter direction in quantum space, so at a 90° angle it has no value, as Cos (90°) = 0.