Molecular diffusion, often simply called diffusion, is the thermal motion of all (liquid or gas) particles at temperatures above absolute zero
As I quoted through the Wikipedia,
The diffusion should be affect of the thermal motion. As on it my first feeling was what is the fundermental force acts on it with the main 4 fundermental forces. I found much details from Force causing diffusion but arise a question considering a single particle.
As this ,when we consider a set of particles, each can collide with the other particle, the particles are moving from the more concentrated place to the lower one.
If we take a vacuum tube and keep a particle there, in the temperature of absolute zero, and then slowly increasing the temperature, the particle starts to move with the thermal motion.The is no way for any collision or way to vary it's momentum which force affects for this motion by the main 4 fundamental forces?