Ultra-fast imaging reveals

The nanoscale is the new frontier of fluid dynamics and its phenomenology can echo at the macroscale as in the canonical example of drop impact on a planar substrate. Unprecedented advances in measurement technology have recently equipped fluid dynamicists with the ability to probe nanoscale effects. The paper by Li, Vakarelski & Thoroddsen (J. Fluid Mech. vol. 785, R2, 2015) uses ultrafast imaging at the hundreds of nanosecond scale to resolve the first contact between the drop and the substrate and thereby reveal the effect of prescribed nano-roughness on contact line motion.