Neil Johnson is a professor of physics at the George Washington University, Washington D.C., who was trained in many-body physics. Many-body physicists focus not on the individual parts of an object or a system but on properties that emerge when these parts interact with each other.
For example, a many-body physicist would be interested in what happens to a group of water molecules when water changes to ice, rather than studying an individual water molecule in great detail.
In the 1990s, Dr. Johnson’s interests took a peculiar turn. “As theory in physics got ahead of experiments,” he told this writer, “we decided to look at data in other areas: traffic, financial markets, etc.” He was in effect entering the realm of social physics, or the physics of social systems.
