Preface We all know very well what life is when we encounter other living beings. Why is it then so dificult to deine life in the framework of the exact sciences? Why is it that there are no clear answers from philosophy or from theology? Maybe we should try to tackle this problem not separately, everybody alone in his ield of science, but rather come to an answer looking at the question from very different angles. This was the idea behind the workshop on “What is life?” in January 2015 in Bern, organized by the Center for Space and Habitability of the University of Bern. Scientists from theology, philosophy, biology, biochemists and space researchers came together to share their view on “What is life?”. This was certainly not an easy endeavor, as several hurdles had to be overcome: different “scientiic” languages, very different methods, reservations and prejudices vis-à-vis the other sciences. About 50 scientists from the different ields rose to the challenge such a conference is posing and the question “What is life?” was discussed intensively during three days. This book is a selection of papers given during this conference and has the intent not to give a inal answer (there probably is none), but to foster discussion on this and other truly interdisciplinary questions in the ield of space and habitability. In order to get a more comprehensive view, several experts in the different ields not participating in the conference have also contributed to this work. One of the major outcomes was that we all learnt to listen to scientists from other ields, to appreciate their methods and to acknowledge the fact that such a topic needs a truly “universal” view. This conference as well as the book would not have been possible without the initiative, enthusiasm and work of Dr. Andreas Losch. His contribution is herewith especially acknowledged. Our thanks go to all participants at the conference, to the authors of the papers of the book and to the referees. We would also like to thank the University of Bern, which made this possible through the Center of Space and xi xii Preface Habitability, as well as to the Swiss National Science Foundation, which inancially supported the conference. Professor Kathrin Altwegg Former Director of the Center for Space and Habitability