 It's a common misconception that only infrared radiation carries heat, in fact any form of electromagnetic radiation can carry heat. The reason we often think infrared carries heat is that things at room temperature or about the temperature of a heater are typically not hot enough to emit visible light, they emit infrared light. For example, you may not think that you are glowing, but if we look not with visible light, which our eyes can see, which has a wavelength of about half a micrometer, but you can get a thermal imaging camera that sees light in the mid-infrared with about 10 microns wavelength. Let's have a look at what the world looks like as seen by that. So what we're seeing is that people, when they are warm, glow, and they glow more the hotter they are at this wavelength. It's blocked by glass, the face is hot, inside of a fridge is cold, but the back of the fridge is very hot and therefore glowing like crazy. You see the cup getting hotter and hotter as heat is conducted along the handle of the cup. Here we're frying an egg. The egg starts off cold, but heat is conducted into it from the fry pan. There's one running. As they run, they get hotter. You can see things like the tip of the nose and nothing like as warm. If you've got hot water and now cold water being poured into a drink, they glow at different amounts. So everything that's hot emits electromagnetic radiation. It might not be visible for something like a human at room temperature at about 10 microns, which is invisible. If something's a few thousand degrees like the filament of a light bulb, then it's actually perfectly visible. That's visible light. And when it hits something else, it makes it warm.