  The onset and the development of the concept of exchange force in quantum
physics are historically reconstructed, starting from Heisenberg's seminal
contributions in 1926 and going through the great developments in nuclear
physics, which allowed the emergence of the idea of force mediating virtual
quanta. Although most of such work was performed in Europe, the last and
decisive effort in this long path was carried out by Japanese scientists in the
1930s. This is the main focus of the present work, which retraces the
achievements of Yukawa and Tomonaga, whose results and mutual interactions are
carefully analyzed and related to those of European physicists.
