Abstract: With the miniaturization of electronic devices and intelligent manufacturing, the problem of heat transfer at ultimate scales is becoming increasingly prominent. Therefore, this paper disscusses the applicability and unification of thermal radiation and thermal conduction at ultimate scales. Moreover, it proposes that it is critical to have a unified theory of heat transfer at ultimate scales, especially for solving the problems in electronics thermal management and atomic-level intelligent manufacturing.

Key words: ultimate scale; thermal conduction; thermal radiation