I was reading an interview of a guy that was a ground breaker in decoding DNA. He said he had a choice to take when he started out as a researcher. He could go into physics, which he loved, or go into decoding biology. He said all the easy stuff in physics was already taken (you needed atom smashers to test stuff) while biology you just needed to look into a microscope and could discover new things. In the early days of amplification, the general rules for tubes were mostly already thought up, Leo just packaged them well and decided output tubes did not have to last ten years.