The investigation of strongly interacting systems ranges from matter inside atomic nuclei to matter under extreme conditions in astrophysics. These systems require the introduction of nuclear forces and a systematic many-body approach to solve the strong interaction particles. Understanding the behavior of infinite nuclear matter provides a path to predict the properties of neutron stars and gives insights to astrophysical phenomena. Three-nucleon forces have to be considered when studying nuclear systems, because their impact is necessary to reproduce properties of nuclei and to correctly obtain the neutron drip line. Moreover, they are needed to predict the empirical saturation properties of infinite nuclear matter. The self-consistent Green’s Function approach paves the way for an improved Ab initio analysis of nuclear matter, thereby providing the basis for the equation of state of neutron stars and supernova explosions.