Andrea Cappelli graduated in physics from the University of Florence in 1983 and received his PhD from the same university in 1987. He is currently Director of Research at the Italian Istituto Nazionale di Fisica Nucleare (INFN), Section of Florence. His field of research is quantum field theory, the main tool of theoretical physics that allows one to describe elementary particles and fundamental forces. In particular, he is interested in the exact solutions of this theory that are possible in low-dimensional systems and in presence of extended symmetries such as conformal invariance. Andrea Cappelli has also been studying applications of exact solutions: to string theory, the theory that could unify particle physics with gravity and to condensed-matter systems in one or two space dimensions that present novel non-perturbative phenomena, such as fractionally charged excitations and are interesting for technological applications. Cappelli has published 60 papers in international journals and has edited one book of conference proceedings. He has co-organized several international conferences in Italy and abroad and coordinates the national research project, 'Low-Dimensional Field Theory, Integrable Systems and Applications'. He is also editor of the Journal of High-Energy Physics (JHEP) and the Journal of Statistical Physics (JSTAT). Elena Castellani is Associate Professor at the Department of Philosophy, University of Florence. Her research work has focussed on such issues as symmetry, physical objects, reductionism and emergence, structuralism and realism. Filippo Colomo is a Researcher at the Italian Istituto Nazionale di Fisica Nucleare, Florence. His current research interests lie in theoretical and mathematical physics. Paolo Di Vecchia is Professor of Theoretical Particle Physics at Nordita, Stockholm, and at the Niels Bohr Institute, Copenhagen. He has worked on several aspects of theoretical particle physics and has contributed to the development of string theory since its birth in 1968.