It has been observed that large international scientific collaborations have been steadily grown in the recent decades; however, the mechanisms and dynamics behind are less well understood. This study examines spatial-temporal structures of scientific collaboration networks from the Microsoft Academic Graphs (MAG) from 1960 to 2017. We quantified the level of international collaborations in research papers and the influence of geographic distance and socioeconomic factors on collaborations. We aim at identifying influence of geographic distance, national boundaries, cultural differences, and frequency of air transportations on the formation of scientific collaborations. The results show that early 1990s are a watershed moment, possibly due to the booming of Internet as well as the end of the cold war. In the recent 20 years, the frequency of short distance collaborations has decreased and the long distances collaborations have grown dramatically. The comparison of such trends with a null model suggests that there are less and less geographical constraints between scientific collaborations (Figure 1). We also found that the positive correlation between the frequency of air transportation and of scientific collaboration between urban areas steadily increases, meanwhile it becomes less likely that two collaborators come from the same country. This suggests that modern transportation facilities help breaking the national or even cultural boundaries of scientific collaboration. Our findings highlight the importance of spatial-temporal analysis to further address the dynamics of scientific collaboration networks.
