So I just watched a short documentary about the history of quantum mechanics which I thought was very interesting. They used the evolution from vacuum tubes to transistors as an example. Not specifically in amps though, but in telephonelines. Turns out the whole wave/particle duality that quantum mechanics revolves around was used to solve the problem of inefficient tubes. Tubes were too bulky and produced too much heat, so they wanted to find something that does the same as tubes, but without the vacuum. It was quantum mechanics that made that possible. How about that! I thought that was quite cool. Seriously, it's only 30 mins long and very interesting, this film. You can find it here: http://www.documentary-log.com/you-are-watching-uncertainty-principle/ By the way, I'm no physics whiz or anything (I failed maths in school, hehe), I just find it an intriguing subject. I thought I'd share.