You look radiant tonight. You always do, as long as your body temperature is above absolute zero. You're radioactive too, but that's another post.
You are radiant because your body emits electromagnetic energy. Now bear with me as I start speaking in tongues for a few lines.
The amount of electromagnetic radiation you emit varies with the fourth power of your absolute temperature. This in large measure determines how "luminous" you are. The frequency of light which is strongest also varies with absolute temperature, and it determines your "color". The quotes are there because this radiation isn't bright enough to see nor at a frequency you can see, but otherwise it is analogous to the electromagnetic radiation we call visible light.
Of visible light, the color that corresponds to the lowest temperature and frequency is red. Light of still lower frequency is thus termed "infrared" ("beneath red").
Alright, so why do you care? Because there are devices that can detect this light, perceive color differences, and map the resulting distribution in color. Because these colors imply certain temperatures, we can use the instruments to detect both absolute temperatures and temperature differences, and at a distance to boot. How cool is that?
This technology has many applications. Consider your house, for instance. You can point a properly designed device at it and see slight temperature variations on the surface. Let's say it's winter - the spots that show as warmer might need more insulation or sealing to prevent the heat loss.
For other applications, consider the electric power generation business. This commonly involves work near very high voltages. Yet the transformers that manipulate these voltages need to be monitored for various conditions that can be detected by abnormal temperature distributions. Using infrared imaging, an engineer can see whether a transformer is working properly from a safe distance.
That's one of the reasons why we had a fancy infrared imaging device at a nuclear power plant where I once worked. We had just received it and were testing it in the office when a certain admin walked by. She was known for her light clothes and lack of undergarments, and she happened to position herself right where the device was pointed (honest!). Some of us happened to notice the resulting display and snickered as it displayed her, uh, temperature distribution. Just as we had thought...
A few years ago Sony introduced a camcorder which was designed to be sensitive to infrared rays, to permit using it under low-light conditions. It so happens that this feature can be used during the day too. And when it is, people wearing light enough clothes appear nude.
Of course the pervs hopped on this right away, and there are entire websites devoted to the resulting images. TechTV just got through warning us about this, and showed some images vivid enough that they felt the need to blur them.
In the interest of science, I went looking for some images to share. Durst you doubt my noble intentions? Check this out. This should be tame enough for any audience (but who knows what kind of bluenoses are out there).
What do you know? It turns out that cancers tend to run hotter than the surrounding tissue, and certain breast cancers can be detected through such infrared imaging. This might be especially effective for smaller-breasted women who have trouble with traditional mammograms.
Wasn't that just a huge steaming pile of enlightenment? Stay abreast of technology here on NWA...