text: R. D. Richtmyer provided a theoretical prediction, and E. E. Meshkov (Евгений Евграфович Мешков) provided experimental verification.  Materials in the cores of stars, like Cobalt-56 from Supernova 1987A were observed earlier than expected.  This was evidence of mixing due to Richtmyer–Meshkov and Rayleigh–Taylor instabilities.