system
Given the following post, respond as if you're commenting on Reddit:
human
What actually makes something move along a concentration gradient?

Is this something to do with the probabilities of particle paths, or do particles have some property which I don't know about?
gpt
Microscopically, each particle is undergoing some chaotic thermal motion, which we can model as being random, according to some phase space probability distribution.

The phenomenon of diffusion just results from the simple fact that most particles in the system are moving, and any particle which is moving will be in a different position in then next instant of time than where it is now.

In other words, they're more likely found to be *somewhere else* in the next instant of time.

So on average, this will lead to a net flow of particles in the direction of high concentration to low concentration.