Facilitating interdisciplinarity: the contributions of boundary-crossing activities among disciplines

It is generally acknowledged that researchers who cross the boundary of disciplines are more likely to produce novel outputs. The knowledge exchanges contributed by boundary crossing provide a good explanation for the underlying mechanism. However, previous studies provide limited empirical evidence on whether and how these contributions are made. This paper analyzes how boundary crossing researchers originated from physics induce interdisciplinary knowledge flows. We find that applied sciences are the most common target domain for boundary crossing activities originating from physics. The normalized citation network shows that boundary crossing contributes to more knowledge exchanges between physics and the target fields than the average level. Beyond the original and target fields, boundary crossing activities also demonstrate spillover effects, causing additional  knowledge flows among a wider range of fields beyond physics. Based on the induced knowledge exchanges, we define distinct roles that boundary crossing outputs play in this process, namely settlers, disseminators, transcenders, and maintainers, and reveal that they have distinct performances on interdisciplinarity. Given the contribution boundary crossing activities have made in fostering interdisciplinary research and knowledge flows, we encourage the funding bodies to break the limitation of disciplinary barriers and establish more grant schemes to support productive and meaningful interactions across different fields.