I was a curious kid. I wouldn’t have been more than eight years old when I learned that green things are green because they absorb the light that isn’t green. Not that I’m claiming I understood it fully. For some time I was mystified as to why green cellophane didn’t make things look red when you looked through it, because I thought absorption was basically light going into the object while reflection was basically light bouncing off the object, so that light going through the object was more like absorption than reflection, because it didn’t bounce off, so if green objects absorbed red light then how come...?
In case you are puzzled by this yourself, absorption isn’t about light “going in”, it’s about light going in and stopping (because its energy has been captured and redirected elsewhere, always at least partly into raising the object’s temperature). The primary distinction is between light that stops and light that keeps going; the latter category is secondarily divided into light that passes through and light that bounces off.
However, at least some of my high-school chemistry classmates had evidently missed this information, because when our teacher explained how the red dyes in a plastic ANZAC Day poppy absorbed shorter wavelengths because the electrons in the iron atoms jumped up a couple of valence shells, or something, one of them exclaimed “So it’s not really red? It’s just that it absorbs the other light?”
This isn’t the Imponderable on consciousness, that’s still to come, so I won’t here speculate on why our experience of colour feels so removed from the Newtonian interpretation of light wavelength and frequency. The point here is this idea that photon absorption is somehow cheating – that there must be a “real red” somewhere which isn’t faked up out of all that physics-y stuff. Because people who have got past that, and are perhaps even now chortling at my sixteen-year-old classmate, are still susceptible to the idea that there might be “real” fear, “real” anger, or “real” love floating around in amongst their synapses and neurotransmitters.
