I get the feeling that the reason it took so long for this invention to be realised may be because of a few interconnected things: It is so obvious when you think of the physics at work, the mildly counterintuitive function of it, and the mindset that “this is so simple that if it doesn’t exist, someone must have tried it 150 years ago and come to the conclusion that it doesn’t work”.<br>Sometimes it is the simplest things…