The Random Walk

One of the hidden commonalities between the heat a diffusion problem and a stock a price, or option price, is that there's a random walk. In the case of the molecules that are being heated, there's some random wack going onof molecules bumping each other. And in the case of pricing the insurance policy, you are, in a sense, summing over all possible future paths of the stock price um. So that the underlying similarity in the mathematics is coming from an assumption of randiveness underneath exactly.