Question: The follow up question to yesterday’s blog post ‘Are You Microwaving Yourself in an Infrared Sauna?’ would be why does infrared light heat things better than visible light? Meaning, you can cook meat with an infrared oven but meat won’t just cook on its own outside in normal light. Is this similar to how microwaves heat things?
Follow Up Answer: Yes, you theoretically can cook meat with visible light. However, visible light has several drawbacks.
First, you’ve got to keep in mind that infrared ovens operate at ~3,000-4,000 watts. For comparison, your normal, everyday kitchen light bulb operates at 30-100 watts. In order to achieve the power of an infrared oven with visible light, it would have to be so incredibly bright to the point of being dangerous to everyone around it.
Second, I mentioned in my post ‘Does heat emit infrared photons or are infrared photons what give things heat?’ that three processes are possible when photons hit matter: transmission, absorption and reflection. The reason why we can see each objects with visible light is because each object reflects a good portion of visible light instead of absorbing it. For example, the reason you can see a red apple is because the apple absorbs everything but the color red! The extra light is reflected and actually lost to the environment. Thus, it doesn’t contribute to the heating process.
So you theoretically can cook food using visible light; however, you would need so much of this light coming from all directions to be adequately absorbed sufficiently enough by the object to raise its temperature enough to eat. The visible spectrum of light is not really for heating, it’s for seeing–infrared is for feeling as heat, not for seeing!