Visualization as a tool for understanding

This paper examines the relation between visualization and understanding. Its main thesis is that visualization is an effective tool for achieving scientific understanding, but, contrary to what some scientists and philosophers have suggested, it is not a necessary condition for understanding. The thesis is embedded in a more general analysis of what scientific understanding consists in, and how it can be obtained. It is supported by a case study of the role of visualization in twentieth-century theoretical physics, especially in the genesis of quantum mechanics in the 1920s and in the development of quantum field theory in the years since World War II.