Rocket science

In its current figurative sense, rocket science has come to signify something that is difficult or hard to understand. It is often used in the negative i.e. 'not rocket science', which means not difficult or easy to understand. Towards the end of WWII, when the Germans were the first to use V1 and V2 rockets as weapons, rocket science soon became the means by which rockets eventually became powerful enough to escape Earth's gravity pull and enter space. The scientists who worked on these early space projects were highly intelligent, brainy people, experts at rocket science in its literal sense. Thirty years later, however, in the 1980s in America, rocket science acquired its current, figurative meaning.