Title: The 2020 Nobel Prize in Physics: The theory and observations of black holes

Speakers: Professor B. Gaensicke, Dr A. Gareth, and Dr E.R.Stanway

Abstract: In this colloquium, members of the department will provide an overview on the topic of the Nobel Prize in Physics 2020. This year’s prize was divided with one half awarded to Roger Penrose "for the discovery that black hole formation is a robust prediction of the general theory of relativity", the other half jointly to Reinhard Genzel and Andrea Ghez "for the discovery of a supermassive compact object at the centre of our galaxy."
We will describe the work of Roger Penrose and his concept of 'trapped surface’, which underpins the singularity theorems that show that black holes form generically in general relativity and not only in special, highly symmetric situations.
We will summarise the experimental techniques used to study the black hole in the centre of the Milky Way and review the observations that were used to quantitatively measure its properties. We will then discuss the wider context of discovery and what we have learnt about supermassive black holes from observations outside the Milky Way. In in particular, we will focus on the key role played by supermassive black holes in shaping galaxy evolution over time.