The constantly expanding volume of scientific research engenders specialization, which narrows the focus of research fields. Does this pattern of scientific growth prevent information from circulating between fields? Does motivation to explore new problems and combine innovations across domains counteract this process? This analysis, based on the Science Citation Index, shows that the distances in citation networks decrease from 1950 to 2018. This provides evidence that the sciences diffuse information more easily over time. The shortened distances are due to more dispersed citation activity between fields and growing centralization of citations. Despite these changes, the clustering of citations did not decrease. Cocitations are slightly more embedded over time, which suggests that cross-field ties create their own field boundaries.

Attila Varga is a PhD candidate at University of Arizona, School of Sociology.