Classic definition, once two objects (or multiple) interact with distinct differences with regard to temperature, the object with higher intensity is giving away heat.
Yet, as above definition seems to be correct, the true phenomenon is more simplistic; once two objects (or multiple) interact, while projecting in 3D Space distinct differences with regard to temperature, both objects are equalizing the difference with regard to level of temperature >< object with higher intensity is progressing toward the object with lower intensity, while object with lower intensity is progressing toward the object with higher intensity, de facto, both objects interact equally and proportionally to their own distinct heat/temp intensity (action vs reaction).
Temperature project inflation, as well as contraction within 3D Sp5ce, de facto, 3D Space is defined by an energy, inflation as well as contraction; 3D Space is energy in given state of expansion vs contraction … .
Yet, inflation vs expansion is defined, in general terms, as kinetic energy within subatomic level <> intensity of vibration within molecular interaction … .
3D Space; relation between inflation vs contraction;
Energy Potential (approximation of neutral) vs Projected Kinetic Energy … .
(neutral in non existent as all physical properties manifest at least vestigial kinetic energy).
Energy/Temp vs Emotions <> Temperature vs +/-
Image; Vitruvian Man, Wikipedia, MJW ).
(Images: Wikipedia, MJW ).