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Open Access Publications from the University of California

Network Dynamics of Scientific Knowledge Reveal a Single Conceptual Core that Declines Over Time


How does scientific knowledge grow? Some argue that science advances by developing a set of core concepts, while others argue complementary or competing core/periphery structures allow for scientific progress. We conducted a large-scale analysis of abstracts from the American Physical Society, spanning 58 years. For each year, we created a network of concepts, where single- and multi-word noun phrases were linked if they appeared in the same abstract. Our results suggest that a single core––rather than multiple cores––best explains the structure of our concept networks. We also see that only a small subset of core concepts (around 10%) remain within the core. Finally, we see a decline in the relative size of the core, driven by the growth of scientific production. The decline in core size is negatively associated with discoveries that push the scientific frontier, which suggests that strong core/periphery structures may be important for innovation.

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