I Degrees of freedom of elementary particles

[Lapidus]

The EM wave and the photon have two degrees of freedom. Their polarization directions and spin states, respectively.

But they move in space, too. I mean light has the freedom to go in all directions in space.

Like a macroscopic ball in 3-D space, which can go all three directions, if there are no constrains.

So why are the degrees of freedom of elementary particle only their spins and charges (e.g. for quarks), i.e. internal properties, and not their freedom to move in space?

 

[mathman]

It has to do with definition. Degrees of freedom refer to intrinsic properties. Direction or speed of motion are not intrinsic.