Welt: The concept that changed physics

Abstract This paper explores a pivotal moment in history when the integration of space and time took place within a unified theoretical framework. The spacetime unification was embodied by the notion of Welt , the German term for world, originating during the period spanning 1907 to 1909 in between the publications on special and general relativity. Emphasis will be placed on elucidating the significance of a connected spacetime and providing a contextual backdrop to key historical advancements. While the conventional narrative often attributes the development of these concepts to a select group of renowned physicists, such as Albert Einstein and David Hilbert, it is essential to recognise the substantial involvement of numerous scientists and mathematicians. Their collective contributions, although sometimes overlooked, laid the foundation for the groundbreaking papers on relativity penned by Albert Einstein. In shedding light on this collaborative effort, the paper aims to underscore the intricate set of ideas that paved the way for Einstein’s seminal work. Furthermore, this paper also hints at the contemporary relevance of spacetime in ongoing research, highlighting its enduring importance in the scientific landscape.