In the early eighties I started to work on the foundations of quantum mechanics with Gianni Cassinelli and Enrico Beltrametti. Though I soon abandoned the research in quantum logic and quantum probability, I own to both of them a lot; in particular, I learned from Gianni the importance of mathematical precision and clarity. After my 'Laurea' in Physics in 1982, I went to the States, and worked with Stan Gudder in Denver. I enjoyed a lot the friendly atmosphere at the University of Denver, with Stan, Vladimir Narodisky and Jean Paul Marchand. At that time, I came to know, almost by chance, the work of Ed Nelson on stochastic mechanics, which drastically changed my way of thinking about quantum mechanics. To such a change contributed also, in an essential way, the collaboration with Asim Barut, from whom I learned that one should not be afraid of questioning the quantum orthodoxy. After Denver, in 1985, I moved to Germany and met Detlef in Bielefeld.
Since in Nelson's theory particles are undergoing some sort of Brownian motion, I felt at that time that it was quite plausible that one could derive quantum mechanics, more or less as one derives standard Brownian motion as the reduced description of a particle interacting with a fluid. After all, this was the first item in the list of open problems that Nelson had at the end of his book 'Quantum fluctuations', the so-called 'background field hypothesis'. Detlef did not find so crazy such an idea, but I eventually end up working with him on standard problems of non-equilibrium statistical mechanics, which was indeed quite useful for me, both for coming to a good understanding of Boltzmann solution of the problem of macroscopic irreversibility, as well as for finally getting a PhD in physics, which I indeed obtained in 1986.
That time in Bielefeld is unforgettable for me: in addition to the work in statistical mechanics, Detlef and I got interested in understanding Feynman-Wheeler electrodynamics and Einstein's 'unified field theory'. In 1986 I met Shelly and learned from him that nonlocality of nature was the only true and unavoidable consequence of EPR-Bell's analysis (given the results of the experiments of Aspect). That was crucial for reaching a good understanding first of stochastic mechanics and then of Bohmian mechanics (and for definitively abandoning the idea of the 'background field hypothesis'). This is how our friendship and collaboration started.