The author proposes to show that the actual crisis in microphysics is principally due to the fact that, as quantum mechanics is a theory of stationary states and reversible movements, it fundamentally ignores the notion of a transitory process. The essential characteristic of quantum theories is the result of an evolution of more than two centuries; a period of development essentially devoted to the description of stationary and reversible phenomena. The author's point of view, which reflects that of the school (...) of Louis de Broglie, is that microphysics must now cross a new threshold in giving up the description of stationary states and the calculation of their transition probabilities in favor of attempting to describe the transitions themselves and explain the origin and stability of stationary states. The future seems to him to be one of a microphysics based on irreversibility. (shrink)