The heavyweight champion among Expert Voices blogs has returned for another semester. “Networks” is a course in economics, sociology, and information science at Cornell taught by David Easley and Jon Kleinberg. Its subject is how the social, technological, and natural worlds are connected, and how the study of networks sheds light on these connections. The class considers such subjects as how opinions, fads, and political movements spread through society; the robustness and fragility of food webs and financial markets; and the technology, economics, and politics of Web information and on-line communities. Each student is required to participate in updating the blog. The public cannot participate in the discussion but we can read the posts, and they are great reading. It is a fairly large course, and during the spring semester last year students produced over 100 high-quality reviews of various networks, written so ordinary folks can understand it. The first week of class this year has already yielded posts on peer-to-peer lending, Swarthmore College’s Genocide Intervention Network, and a recent article in a medical journal that likens obesity to a contagious disease that spreads within social networks. Check it out here. Then add it to your bookmarks or make it an RSS feed to your homepage.