Light is one part of a vast spectrum, and the colours that we see are only a small part of a larger phenomenon. We can divide this spectrum up into regions such as visible (the region that our eyes and typical cameras can see), and ultraviolet (that causes sunburn), and even X-rays (for seeing broken bones). Infrared light, like UV and X-Rays, is also invisible but has less energy per photon (the individual particles of light) and so poses little danger. However, the infrared region of the spectrum has two incredibly useful features: this is where molecules jiggle or vibrate, and it’s also the kind of light that warm objects naturally give off — like the heat you feel from your hand or a cup of coffee. Cameras that see this heat are great for defence and security – especially for night-vision! But scientists can also use this kind of energy to look for specific molecules, which helps with things like medical imaging.
The problem is, everything gives off this heat, so the tiny signals from specific molecules can get hidden. The question is: is there a way to separate the heat glow from the special signals from vibrating molecules that we care about?
