Now, let me distinguish between two uses of the word heat.. Heat is a sensation that occurs when temperature-sensitive nerves in our skin detect a difference between the temperature at the skin surface, and temperature deeper in your body.However, the term heat also has a specific meaning in physics, meaning thermal energy.The sensation of heat comes from nerve-endings that detect the temperature of the skin. The temperature of the skin increases when heat energy flows into the skin.ow, when photons strike your skin, some of them are reflected. That's how we can see people! We see the photons visible that are reflected from their skin. But not all the photons are reflected--if they were, then people would look pure white.