Evolution of Physics Sub-fields

摘要

We study the evolution and relationships between sub-fields of Physics using the large data set of articles published in the various physical review journals from 1985-2010. Each article is assigned to some PACS codes by their authors which represent specific sub-fields of Physics. We construct a weighted network with nodes as PACS codes and there is a link between two PACS codes if there is an article assigned to both these codes. The weight of a link represents the number of articles in which both PACS codes appears. We study the time evolution of PACS network at various hierarchy levels of PACS codes. We observe that sub-fields Physics of elementary particles and fields. Nuclear Physics and Condensed matter physics have stronger connections inside the field compared to connections to other sub-fields. We also observe that both condensed matter physics sub-fields are strongly related compared to any other pair of sub-fields.