For ten points, name this process of small, random movement in a fluid.
One factor that made the explanation of this a popular problem was Louis Bachelier's attempt to use it as a model for the stock market. It is the basis for a theoretical motor that uses a fixed alternation in ratchet potential. Current theory models it under the Langevin equation, and its original explanation was used to definitively prove the existence of atoms by Jean- Baptiste Perrin and Albert Einstein. It is caused by the random discrepancy among molecular pressures on different portions of the particle. For ten points, name this process of small, random movement in a fluid.
One factor that made the explanation of this a popular problem was Louis Bachelier's attempt to use it as a model for the stock market.
{Brownian} motion