Thesis proposed by Thomas Guérin (LOMA, CNRS, thomas.guerin@u-bordeaux.fr) Years 2020-2023 - Thesis funded by the University of Bordeaux ; Location: Bordeaux, FRANCE The first passage time is the time that a random walker, such as a diffusing molecule, needs to find a target for the first time (see figure showing an example of random trajectory joining a star source point and a round target ppar tguerin - Thèses hors de l'EDPIF