Sébastien Merkel is a professor at the Université de Lille, France. He performs extreme conditions experiments to study microstructures in polycrystals, their mechanical behaviour, and their relation to phase transformations. The overall goal of his work is to constrain the dynamics and formation of the Earth's mantle and inner core from observations. He was the PI of the bilateral ANR-DFG TIMEleSS grant in 2018-2022, with the aim to studying interfaces in the Earth’s mantle combining observations from seismology, mineral physics experiments, microstructures, and wave propagation modeling. He recently obtained an ERC Advanced Grant, HotCores, to work on the Earth's inner core.