In Memory of Giovanni (Gianni) Morchio

A cold day of February 2005. I am strolling across the department of physics’s corridors as a first-year PhD student. I have recently arrived in Pisa while still dazed by the change of city and life, and I am in search of doctoral courses to include in the first year plan of my graduate study programme. While passing by the open door of a lecture room where a class has already started, I happen to notice a notification sheet posted at the entrance, laconically saying “course on mathematical methods for quantum mechanics”. Intrigued, I enter the room, apologising for the delay, and I am greeted by a shy and good-natured lecturer. I sit down and start listening to his lecture. The sensation I felt that day is the same that has always accompanied me during the years of study and research that I had the privilege of sharing with Gianni. I preserve with particular affection several memories of that period of my life. A first one is related to the not so smart impression I made when, in a lecture, Gianni introduced the fascinating topic of spontaneous Lorentz symmetry breaking in the charged sectors. That caught me quite incredulous and I then asked him to repeat that part of the discussion, somewhat convinced that he should be wrong. And yet Gianni, after hinting a smile and without reminding me at all my own inexperience, calmly unfolded again the main parts of the reasoning, additionally providing enlightening clarifications.