regarded as one of the most influential, visionary, and wide-ranging scientists of his time. Wheeler published important work in nuclear physics, notably his 1939 paper with Niels Bohr on nuclear fission. From the mid-1950s, he was one of the leading figures in the revival of interest in the general theory of relativity, popularizing the expression ‘black hole’ and writing or co-writing influential books on relativity theory. He also made important contributions to the foundations of quantum theory, the theory of elementary particles, quantum gravity, and quantum information theory.