Playing with time machines in laboratories

YOUNG RESEARCHERS MATH SEMINAR

Conferenciante: Gerardo García Moreno (Universidad de Granada)

Abstract: General Relativity is the most succesful theory we have for describing gravitational phenomena. Its range of applicability is vast: from solar system scales to cosmological scales. It is well-known that GR allows the existence of time machines: devices that are able to generate Closed-Timelike-Curves (CTCs). Although these kind of objects are allowed in GR, most researchers believe that they cannot occur on macroscopic scales. However, it is widely believed that a full quantum theory of gravity would be required to fully understand the mechanisms beneath this "Chronology Protection Conjecture". In this talk, I will describe the status of this conjecture within the context of analogue gravity. Analogue gravity is a research programme which investigates analogues of general relativistic gravitational fields within other physical systems, typically condensed matter systems, with the aim of gaining new insights into their corresponding problems. There exists a huge catalogue of analogue models: from classical and quantum fluids to optic systems.

After briefly reviewing the role of time machines and the Chronology Protection Conjecture in General Relativity and introducing the analogue gravity program, I will jump to discuss the content of our last paper: arXiv:2201.11072 [gr qc]. We examine carefully whether it is possible to simulate these kind of spacetimes with CTCs within analogue gravity. Although I will focus the discussion on a concrete analogue system, sound waves propagating on top of a Bose Einstein condensate, I will explain the extension of our results to other kind of analogues.