Describing the evolution of science is a salient work not only for revealing the scientific trend but also for establishing a scientific classification system. In this paper, we investigate the evolution of science by observing the structure of and the change on keyword co-occurrence networks. Starting from seven target physics fields and their initial keywords selected by experts from the Korean Physical Society, we generate keyword co-occurrence networks to capture better topological structure with our proposed approach. In this way, we can construct a more relevant and abundant keyword network from a small set of initial keywords. With these networks, we successfully identify the scientific sub-field by detecting communities and extracting core keywords of each community. Furthermore, we use a time-snapshot keyword network to trace the temporal evolution of sub-fields, and the resultant temporal change of the community membership explains the evolution of the research field well. Our approach for tracing the evolution of a research field with a keyword co-occurrence network can shed light on identifying and assessing the evolution of science.

中文翻译：

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用关键字共现网络追踪物理学的演变

描述科学的演变，既是揭示科学发展趋势，也是建立科学分类体系的一项重要工作。在本文中，我们通过观察关键词共现网络的结构和变化来研究科学的演变。从韩国物理学会专家选择的七个目标物理领域及其初始关键字开始，我们生成关键字共现网络，以使用我们提出的方法捕​​获更好的拓扑结构。这样，我们就可以从一小组初始关键词构建一个更相关、更丰富的关键词网络。通过这些网络，我们通过检测社区并提取每个社区的核心关键字，成功地识别了科学子领域。此外，我们使用时间快照关键字网络来跟踪子领域的时间演变，由此产生的社区成员的时间变化很好地解释了研究领域的演变。我们使用关键字共现网络跟踪研究领域演变的方法可以阐明识别和评估科学的演变。