Perrin used it to model atomic motion to find Avogadro's number based on Einstein's 1906 description of it.
The Smoluchowski model describing this process considers collisions with a very massive test particle. This process can be mathematically described by considering spatial interactions, a time-dependent noise term, and a parameter from Stokes' law in the Langevin equation. This process can be seen as a small-step limit of a random walk, as it consists of a continuous stochastic process called a Wiener process. Perrin used it to model atomic motion to find Avogadro's number based on Einstein's 1906 description of it. For 10 points, identify this type of motion initially observed in pollen grains by its namesake Scottish botanist.
The Smoluchowski model describing this process considers collisions with a very massive test particle.
{Brownian} motion/dynamics [do not accept “{Brownian diffusion}”]