Chromosomal interaction plays a critical role for numerous cellular activities. One important step during the interaction is the encountering of two chromosome segments, which is the speed limit of the subsequent processes. How fast two segments encounter is the first passage problem. In this defense, I will introduce the Chemically Induced Chromosomal Interaction (CICI) method and how we used it to study chromosome diffusions and capture the first passage events. I will also apply polymer physics models to understand the chromosome dynamics.