Final Activity Report Summary - ANALOGUE GRAVITY (Gravitational physics from the analogue gravity perspective) The physics associated with the propagation of waves in a curved spacetime, like the universe in which we live, is formally equivalent to the propagation of different signals in condensed matter systems. The simplest example is the propagation of acoustic waves in inhomogeneously moving (irrotational) fluids. Currently, researchers are taking advantage of this fact to, on the one side, try to reproduce scale models of black holes and other interesting spacetime geometries in earth based laboratories and, on the other side, obtain new insights in gravitational physics by addressing some of its problems under the light of the notions and techniques proper of condensed matter physics (I would like to highlight that the inter-connexions between gravity and condensed matter have been barely unexplored up to now). The work performed under the ERG support has been centred on this line of research currently known as analogue models of general relativity or analogue gravity. The main outcome of this one-year period has been the publication of an extensive review article (to appear in 'Living Reviews on Relativity') on analogue gravity. In this article, it is described the present state of the art of the research area pointing out which are in our view the most interesting problems to be addressed now on. We (me and my collaborators) have tried to write the article in a manner as pedagogical as possible, making the article useful as an introduction to the field for new graduate students. Apart from this article, I have published another paper analysing the causal properties of a catalogue of spacetime geometries containing horizons selected because their naturalness from the point of view of acoustic systems. These geometries are from the point of view of acoustics equivalent to the characterisation of different black holes by their mass and charge. The analysis on this paper provide new insights about the most appropriate ways to reproduce different aspects of black hole physics in laboratory. In addition, it shows from a condensed matter perspective what is the meaning of analytical extensions of geometry.
