 This instability at the interface between two fluids of different densities occurs when the lighter fluid is pushing the heavier, and was vital to the interpretation of experiments with explosives, predicting the effects of an explosion, the design of the neutron initiators, and the design of the atomic bomb itself.Chadwick remained only for a few months; he was succeeded as head of the British Mission by Rudolf Peierls.The original idea, favored by Groves, was that the British scientists would work as a group under Chadwick, who would farm out work to them.