Question regarding the emission of infrared radiation, for personal knowledge. Why do humans emit infrared radiation? Is it because it just so happens that the energy humans absorb (from sunlight)/ the energy humans produce just so happens to correlate to the frequency of infrared, as according to E = hf? Or am I wrong in my assumptions of where the source of the energy comes from? Additionally, I read that many everyday objects, such as an ice cube or a textbook emit infrared. How can objects such as these, which have a much lower temperature than humans (which I assume correlate to lower energy) emit in the same frequency. Can this only be the case if infrared has a large spectrum, and thus can correlate to different amounts of energy?