I understand the basics of this principle: the force of gravity acting downward on an object becomes equal to the air resistance acting upward on the object because as the object speeds up, air resistance increases. My question was much more specific: I thought that the force on an object increas...

Consider the Lorentz group $SO(2,1)$ in 2+1 spacetime dimensions. It's little group for massless particles should be just "$SO(1)$", which is just a trivial group with an identity element. So I expect that the massless particles should not have any propagating degrees of freedom in 2+1 dimensions...