In 2015 Zhong Fang and Hongming Weng were part of a team to predict and confirm that tantalum arsenide is a Weyl semimetal. These exotic materials contain the first evidence for the existence of Weyl fermions, massless particles predicted in 1929 as a solution of the Dirac equation. In this podcast, Hamish Johnston catches up with Fang and Weng at the Institute of Physics of the Chinese Academy of Sciences in Beijing and asks them about their work on Weyl semimetals and other topological materials.