(FILES) A picture shows a building of the European Organisation for Nuclear Research (CERN) on January 29, 2019, in Meyrin, near Geneva. The CERN physics laboratory chief welcomed China hitting pause on its major particle accelerator project, calling it an "opportunity" to ensure Europe's rival plan goes ahead. Ten years ago, China announced its intention to build the Circular Electron Positron Collider (CEPC), which would be the world's largest particle accelerator at 100 kilometres (62 miles) long. But Beijing recently put the project on ice, CERN's director-general Fabiola Gianotti told a small group of journalists in a recent briefing. (Photo by Fabrice COFFRINI / AFP via Getty Images)