Since a falling apple around 1665 worked its magic in the imaginative mind of a youthful farmer at Woolsthorpe in Lincolnshire, the meaning of the word action and of the equal and opposite reaction, has been investigated in science and technology. More than 300 years ago this irreversible process had consequences that led to the development of a theory of gravitation still used by space agencies even today. It should be noted, however, that Isaac Newton’s intellectual concept of action was the equivalent of force1 - which he defined as the rate of change of linear momentum2 (or net impulse per second) which could be equated to.
