1. The problem statement, all variables and given/known data The problem requires me to find the entropy of a diffusion constant as a function of time (I guess in terms of diffusion coefficient) 2. Relevant equations Perhaps Heat / Diffusion kernel S = k p lnp 3. The attempt at a solution I assume it was a delta initial condition then apply the kernel. However I need to turn the entropy definition into an integral over space. The kernel times differential volume is the probability finding the particle in that space but the natural log term is tricky.