Georgia Institute of Technology College of Sciences

We consider the first-passage percolation model defined on the square lattice Z^2 with nearest-neighbor edges. The model begins with i.i.d. nonnegative random variables indexed by the edges. Those random variables can be viewed as edge lengths or passage times. Denote by T_n the length (i.e. passage time) of the shortest path from the origin to the boundary of the box [-n,n] \times [-n,n]. We focus on the case when the distribution function of the edge weights satisfies F(0) = 1/2. This is sometimes known as the "critical case" because large clusters of zero-weight edges force T_n to grow at most logarithmically. We characterize the limit behavior of T_n under conditions on the distribution function F. The main tool involves a new relation between first-passage percolation and invasion percolation. This is joint work with Michael Damron and Wai-Kit Lam.