The focus of this workshop will be on different aspects of modern theoretical cosmology, the challenges of the theory being consistent with experimental data, and the unavoidable connection of cosmological models with the quantum nature of the vacuum. A basic question in modern cosmology is: why we do not see vacuum fluctuations at cosmological scale? In addition, should the singularities of cosmological theories be treated as necessary ingredients of the classical theory or should them be considered as indicators of an underlying quantum theory, yet to be discovered? We aim to bring along to this workshop all the leading scientists working on those problems and discuss state of the art results on the above, strongly interdependent, areas of fundamental physics. The workshop will hence cover topics related to modified theories of gravity, theories of dark energy and inflation, the description of the universe’s evolution according to these theories and the incipient but compulsory modification of those within the theoretical frameworks of quantum gravity, including loop quantum cosmology, an elegant theory providing up to date a singularity free cosmological evolution. Describing and understanding the quantum vacuum is always a challenge to all these theories, as is also the comprehension of the main manifestation available of the quantum vacuum at nanometric scales, namely the Casimir effect (e.g., when confronted with van der Waals forces).