A great deal of research is carried out at the IPhT. Its main aim is to formulate and study the physical and mathematical laws that govern our universe, its structure and its organisation, and it covers almost all the major subjects of modern theoretical physics: from the study of fundamental interactions, aimed in particular at describing the primordial universe, to the development of models for understanding certain biological structures. They also involve the mathematical study of complex systems in statistical physics and field theory. Beneath the diversity of the systems studied lies a profound unity between the various mathematical formalisms used to describe them.