David Bacon, PhD, University of Portsmouth, UK

In Observational Cosmology as it stands, there are several different types of entity which do not appear directly in our telescope images but for whose existence we have good evidence. In this talk I will present the latest results from the Dark Energy Survey (amongst others) providing new insights into these components: dark matter, gravity, dark energy,  and neutral gas. In particular, I will present our most recent approach to mapping dark matter, together with constraints on gravity theories from gravitational lensing in combination with dynamical information. I will discuss the anomalies we are finding in the expansion rate of the Universe, and will conclude with discussion of the imminent prospects for mapping the neutral hydrogen in the Universe.