Physicists have made water droplets emit white light for the first time using laser pulses. Jean-Pierre Wolf of the University of Lyon 1 in France and colleagues used femtosecond pulses to create nanosized regions of plasma inside the spherical droplets, and this plasma gets so hot that it emits white light. Wolf says that the achievement could lead to a new technique for monitoring the composition of clouds and biological pollutants in the atmosphere (C Favre et al 2002 Phys. Rev. Lett. 89 035005).