Peyresq Physics Workshops 11 and 12—'Micro and Macro Structure of Spacetime', Peyresq, Alpes de Haute Provence, France (17–23 June 2006 and 16–22 June 2007)

Abstract

This special issue is devoted to the proceedings of the workshops Peyresq Physics 11 and Peyresq Physics 12 on 'Micro and Macro Structure of Spacetime', which were held on the 17–23 June 2006 and 16–22 June 2007, respectively, in Peyresq, Alpes de Haute Provence, France, and organized by E Gunzig, B-L Hu and one of us (EV). These workshops are part of a series of annual meetings which bring together around 20 physicists active in different areas of theoretical physics.Uncovering the microscopic structures of spacetime is the goal of quantum gravity and string theory. It is often considered as the 'holy grail' of theoretical physics because it is believed that all fundamental forces are unified at that level of description. Macroscopic spacetime refers to astrophysical and cosmological structures and processes in the observable physical world, from black holes to the cosmos, from the second law to the arrow of time. The challenge theoretical physicists now face is to infer the micro structure of spacetime from the observed macro phenomena, and to deduce the multifarious manifestations of our world from any such candidate theory. To do so demands a careful re-examination of the foundational issues of quantum physics and general relativity (such as intrinsic and quantum gravity decoherence), the origin and nature of symmetries in spacetime (such as Lorentz symmetry) and the conditions where they may be violated, as well as their intersections (such as the physics of the early universe and the end states of black hole evolution).One asks how and why these two pillars of modern physics appear to be so incongruous with each other. Is it because their basic tenets and assumptions are at odds to each other? For these quests one needs to draw upon concepts and techniques from close disciplines such as those found in topology and geometry, or other subdisciplines of physics such as particle physics, strings and loops, statistical mechanics and mesoscopic phenomena, atomic-optical and condensed matter physics. The richness of this theme spans a diverse spectrum of current topics which can be gleaned from the titles of the talks presented in these two meetings.Peyresq is a medieval Provençal village situated 100km from Nice at an altitude of 1528m. The village was founded in the early 13th century. At thebeginning of the 17th century there were around 50 houses and by 1851 the village counted 208 inhabitants distributed among 53 families. Like many othervillages of Haute Provence, it was almost completely deserted after the Second World War. During the 1950s the village was progressively entirely rebuilt inits original spirit and style by students of Belgian universities, mainly the Université Libre de Bruxelles, under the guidance of Mady and Toine Smets.The aim was to create a 'Foyer d'Humanisme', an international humanistic center for cultural, artistic, and scientific pursuits.The workshops were financed by the Fondation Peyresq, Foyer d'Humanisme, the Fondation Nicolas Claude Fabri de Peyresq, and OLAM (Association pour laRecherche Fondamentale, Brussels). We would like to thank all these institutions for their help and financial support. We extend our warm appreciation to Madame Mady Smets without whom none of this work could have come to light. We would like to thank all the participants for the many lively discussions that we have enjoyed and for their effort in preparing written contributions. We would also like to thank the editorial staff of Classical and Quantum Gravity, especially Tom Spicer, Joseph Tennant and Eirini Messaritaki, for their support and efficiency in preparing this volume. Finally, we thank Edgar Gunzig and Bei-Lok Hu as the main driving forces behind the organization of these workshops.