Here's a thought experiment about the way that heat is transferred through radiation.
Humans can physically feel when a hot object radiates heat on them, such as a campfire or an infrared-based space heater. But can humans feel cold objects the same way?
Say that a scientist is working in a research station in the South Pole in winter, when the outside temperatures reach -80 celsius. (Feel free to also imagine it as 0.1K for the sake of the experiment.) Say that the research station is a big building with multiple floors and rooms within each floor. It has a strong environmental control system that keeps the air at a pleasnt 25 degrees all over the building. However, the outside walls of the building are still very cold, say -40 celsius. The internal walls are at room temperature.
Say that our scientist is walking from an internal room in the building to a room that has one or several external walls. Say that his body is surrounded by an equal 50-50 mix of external walls and internal walls. The air temperature is still 25 degrees. Will our scientist feel the coldness of the wall? Will the wall feel like it's radiating cold on the person?
Follow up question: Assuming the answers to the previous questions are yes. Say that we place a person in a closed room, where the walls on all sides, as well as the floor and ceiling are at a temperature of 0K. The air in the room is kept at 25 degrees celsius. The person is not touching the walls or the floor (say they have incredibly insulating shoes). Will that person freeze to death in minutes as they would in space?
Best Answer
Yes they will feel the coldness, but it's the lack of heat radiation, not radiating coldness. Essentially, the scientist's body is radiating more heat than it is receiving, and it is this difference that they are feeling.
If the scientist doesn't know how heat and infrared radiation work, they may be hard pressed to tell that it's lack of heat radiation and not cold radiation just from what they can feel.