The post is about a PhD, not the entire career. I really doubt somebody is able to revolutionize physics in a PhD dissertation. The low hanging fruit is simply not there anymore. Later in your career, it might be possible though.Talk about setting small goals, is that what you want your career to be? A tiny bump on the surface of the circle of knowledge? If that suits your fancy, go right ahead, but what I want to do is accumulate a bunch of these tiny dents (funded by naive organizations such as NSF and NIH) and burst the bubble like Einstein did!