The discovery of the accelerating expansion of the Universe arguably provides the most profound puzzle in contemporary physics. It implies that either the Universe is dominated by a component, dubbed “Dark Energy”, that turns gravity's pull into a push, or that General Relativity, our understanding of gravity itself, breaks down on cosmological scales. Either way, it deeply challenges our knowledge of the basic laws of Nature. Characterizing and understanding the origin of the accelerated expansion is a truly global and interdisciplinary enterprise.
As general structure for the programme, we aim at discussing probes of cosmic expansion, tests of structure growth and at understanding the implications of combining them. Different competing theoretical scenarios, both of the “modified matter” and “modified gravity” kinds, will be compared against each another. Both the theoretical and experimental/observational viewpoints will be represented and discussed.
Key scientific questions to be addressed include: