"The aim of EXCHANGE is to achieve a breakthrough in the understanding of magnetism and magnetic phase transitions on the time and length scale of the exchange interaction, the strongest force in magnetism. This will be achieved by developing and applying novel, beyond the state-of-the-art femtosecond X-ray and picosecond THz techniques, in combination with laboratory based ultrafast optical techniques and close interaction with new theoretical developments.Magnetism is essentially a phenomenon of angular momentum and the interpretation of magnetic order is based on the concept of exchange interaction. So far, the understanding of the physics of magnetism, including its dynamics, has only been achieved for systems close to their thermodynamic equilibrium. Magnetism at the length and time scale of the exchange interaction, that is to say, at nanometer length and femtosecond time scales, is completely unknown. Yet, future magnetic data storage aims at Tbit densities switched at THz rates, exactly this regime.Recent developments of a new generation of femtosecond X-ray and picosecond THz free electron lasers create the opportunity, now for the first time, to experimentally visualize the transfer of angular momentum under strongly nonequilibrium conditions and thereby provide a so far inaccessible view to the strongest and most fundamental force in magnetism, the exchange interaction. When successful, this will strongly advance the frontiers of knowledge in the Physics of Magnetism, with a high potential to impact contemporary technologies for recording and processing magnetically stored information."