The Quantum of heat is the thermon and only the thermon. OKAY. Not the electron, not the photon, and not the phonon. If you disgree please check out: http://www.journaloftheoretics.com/Articles/3-4/commentary3-4.htm Jacob Ghitis states in the Journal of Theoretics: "I insist in the existence of the "thermon," as a quantum of heat. (Curiously, I just read for the first time about "thermion," a name no longer in use, since it was applied to the electrons ejected from the cathode of the vacuum tubes, which no longer are in use.) The phonon would be a quantum of "infra-thermic" energy, also a manifestation of vibrating electrons. The photons emitted by electrons "excited" in a peculiar way manifested by allegedly jumping to a higher orbit, are peculiar electric manifestations." Electron is the quantum of negative electricity and not heat Photon is the quantum of electromagnetic radiation (including light) and not heat. Phonon is the quantum of mechanical vibration (including sound) and not heat.