How do you define a breakthrough?
A breakthrough is an entirely new model. It's a new, unexpected way of thinking about an old problem that provides a new solution, makes predictions, and has implications for other areas. It uses information from an old model, but moves beyond the old model in a significant way --- not as a logical extension but as a jump. A breakthrough tends to change the way people in a field view the field.
Major breakthroughs in human science include (but aren't limited to) Einstein's ideas, Darwin's ideas, Newton's ideas, Galileo's ideas, and Copernican ideas. These ideas shattered everything that came before them. Less-major breakthroughs include washing your hands before you do surgery, the discovery of antibiotics, recording devices, telephones, and so on.
The key is that it has to be a completely new idea, not an extension of an existing model. Some of these ideas seem obvious now ("Wash your hands!") but they weren't at the time.
I don't believe that we've been having these kinds of breakthroughs in other areas so often that we don't see them as breakthroughs.
It's true that they happen outside the system (e.g. Einstein). But not always (e.g. Newton, Cabibbo, Feynman, Rutherford, the Curies). What I'm arguing is that by shoving creative, thoughtful people out of academia, we're damaging our ability to keep, umm, breaking through.
