It is postulated that energy fields in space and matter are quantized by an entity having coincident properties of wave and virtual matter. A unified link between thermal radiation and conduction was established as confirmed by Planck's quantum theory, and a unified heat transfer equation was developed. One-dimensional, steady-state thermal conduction was solved by using approximate scatter and mobility models in this equation. Coefficient of thermal conductivity of various materials were calculated and compared with the literature. Even with approximate scatter and mobility models, a good agreement was observed. (C) 1999 Elsevier Science Ltd.