Molecules above absolute zero emit thermal radiation in the form of photons due to their kinetic energy and molecular vibrations. The source of these photons is linked to the electromagnetic fields created by the random movement of charged particles within the material. Even though individual molecules do not possess a temperature, the collective behavior of many molecules contributes to the overall thermal radiation. When heat loss through all means except radiation is considered zero, it emphasizes that radiation is the primary mechanism for energy loss. Thus, the emission of photons is an inherent property of heated materials, driven by their molecular dynamics.
