Comment on R. D. Schuiling’s Paper
To appreciate the essential scientific reasons for the possible existence of a nuclear reactor at Earth’s center, it is necessary to understand precisely the oxidation state of the deep interior of the Earth as well as the nature and probable circumstances of Earth’s origin, which led to that state of oxidation. For example, in referring to the quote from Wheeler et al. (2006), “the transfer of U from metal sulfide to silicate under our experimental conditions is so complete that insufficient U would remain so as to be of any importance to the core’s heat budget,” Schuiling neglected to note that the silicate used in the laboratory experiment contained 8% FeO. A more highly reduced silicate — nearly devoid of FeO, such as MgSiO3, consistent with the enstatite-chondritic deep interior of the Earth — would have yielded a significantly different laboratory result. Similarly, in referring to elemental behavior using Goldschmidt’s term “chalcophile,” Schuiling fails to mention that chalco-philicity is related to state of oxidation. Even making use of some condensation model, as Schuiling does, necessitates assuming a particular pressure, which leads to a particular range of oxygen fugacities. Schuiling adopts without reservation the so-called standard model of solar system formation, evidently without realizing that the resulting state of oxidation in that contemporary formation model would inevitably lead to Earth having an insufficiently massive core.