Galaxies are not solitary entities. The Milky Way is also surrounded by numerous dwarf galaxies; if one of these dwarf galaxies gets too close to the Milky Way, it will be destroyed by it through tidal forces. In addition, the Milky Way even has a large neighbour, the Andromeda Galaxy, to which it is gravitationally bound and with which it will eventually merge. In massive galaxy clusters, up to 1000 galaxies can thus be bound and interact. However, such interactions occur on time scales beyond several million years. How can you study something that happens so slowly from a human perspective? Nowadays, astrophysicists can simulate the development of a universe on a computer: from a time shortly after the Big Bang to the present day. This makes it possible to trace and understand these interactions.