Leo Kadanoff passed away recently, and his ideas have had far-reaching consequences in many areas of physics. He took the fist important step of recognizing the role of “scale transformations”, which was embodied in his idea of “block spins“, at critical points. This visionary idea soon led to Wilson’s development of the renormalization group (RG).
On a personal level, I have found that understanding the concepts behind the renormalization group to be quite challenging. Many of the treatments are from a quantum field theoretical perspective, which to an experimentalist like me, present their own difficulties. I therefore found the short introductory article by Maris and Kadanoff entitled Teaching the Renormalization Group to be extremely valuable. It conveys (in 6 pages!) the main ideas behind the RG approach to phase transitions and critical phenomena.
Of course, the article only leaves the reader wanting more, as it is brief and to the point. However, I see this as a positive! It spurs curiosity. I see myself coming back to this article repeatedly even after having surmounted more difficult texts on the topic.