Gravity as Thermodynamics: towards the microscopic origin of geometry

ESF Exploratory Workshop

5-8 September – 2011

SISSA/ISAS Trieste – Italy

Description and purposes

To date, the format of the workshop is still preliminary (see the program). It will consist of a number of talks in which the various ideas currently being developed will be presented, divided in thematic sessions. Given the exploratory nature of the workshop, there will be plenty of  organized discussion sessions, to let the participants (expected to come from rather different research areas) interact actively.

The workshop will focus on the idea that geometry of spacetime, which encodes the gravitational phenomena in Einstein's General Relativity, could be interpreted as a thermodynamical variable and that its dynamics could be understood as a form of thermodynamics. However, within this broad (and somehow vague) ensemble of ideas, a number of primary objectives can be listed and used as a guide, to make the workshop useful and productive. 

First, a review of known results in this context will be provided, in an attempt to place them within a coherent and complete perspective, while pushing for further developments. The second aim will be to survey the proposals currently on the table for the microscopic quantum degrees of freedom of spacetime, coming from various corners of quantum gravity research, and to re-interpret them in light of the gravity/thermodynamics correspondence. On top of the task of identifying the correct degrees of freedom there are a number of rather urgent questions regarding the explanation of how they are dynamically assembled, how the macroscopic limit is achieved, how the geometrical quantities arise from their statistical mechanics, and how the thermodynamic perspective can help in addressing any of the above issues. Much of the discussion will be devoted to these points. In addition, the understanding of the limits of the idea that geometrodynamics is a form of thermo/hydrodynamics is equally relevant. To this purpose, it is important to have also critical views on the subject, coming both from analyses of classical aspects of gravitation that are difficult to frame in the thermodynamic picture, and from approaches to quantum gravity based on different, if not orthogonal, conceptual starting points.

The very nature of this particular perspective on gravity makes it very interdisciplinary, but also rather poorly developed in comparison to other approaches to quantum gravity.  One of the goals of the workshop is also to give an impulse the research in the area, to try to build a coherent interdisciplinary background, involving classical and quantum gravity as well as condensed matter theory and statistical mechanics (hopefully leading to cross fertilization).