Uncertainty Relations and Complementary Principle

One of the most known and fundamental results in quantum mechanics is given by the uncertainty relations discovered by W. Heisenberg[aut]Heisenberg, Werner Karl. In this chapter we will discuss them, highlighting the connections with the complementary principle pointed out by N. Bohr[aut]Bohr, Niels. Moreover, examples of the connections between the micro- and the macro-world will be presented together with some interesting debates on the meaning of the new-born quantum mechanics held in 1927 during the Como Congress and the fifth Solvay[aut]Solvay, Ernest Conference.