This paper was the prologue to the first book published by Gabriel Barcelo on the Theory of Dynamic Interactions, entitled: The Flight of the Boomerang. However, this text, is fully current, as well as the book itself. The book described mainly the initial historical analysis made by Dr. Barcelo on the rotational dynamics. For Professor Garcia Moliner, the book contains an extremely positive message. It shows us that scientific research consists of constantly questioning hitherto accepted theories and seeing if they can always be applied to new situations.