The diffeomorphism group of an exotic sphere

This thesis is concerned with the diffeomorphism groups of exotic spheres. A smooth homotopy sphere is a smooth manifold, which is homotopy equivalent to a sphere, but not necessarily diffeomorphic. If it is not diffeomorphic, it is referred to as an exotic sphere. There is an evaluation map from the diffeomorphism group of an exotic sphere to the exotic sphere itself, given by evaluation at a basepoint. Methods from homotopy theory and orthogonal calculus are used to investigate the existence question of a section of this evaluation map. The obstruction to the existence of such a section is given by an element in a certain homotopy group. The main result is the non-existence of such a section in dimension seven in the case of the generator of the Kervaire-Milnor group of homotopy spheres.