Why Do We See Colour?
This video explores what colour is and how we perceive it. However, if you’ve already watched the video you know that, and if you haven’t, what I want you to think about is this:
If a tree falls in a forest and no one is around to see it is it still green?[/vc_column_text][/vc_column][vc_column width=”2/3″ animation=”none” column_padding=”padding-4-percent” column_padding_position=”all” background_color_opacity=”1″][vc_column_text]
Transcript
Recently the internet was divided over this photograph of a dress. Team white and gold, and team blue and black where both adamant about their perception of this dress being correct. There were a lot of great follow up videos explaining why people perceived it differently.
However, in some ways, everyone was wrong. Although we often think of colour as an inherent quality of an object, the truth is much more complicated than that. When we look at something, light hits the light sensitive parts of our eyes, and our brain interprets the signal. This ties into what a lot of other science people on the internet have been telling us, the reason we see the dress differently is because our brains aren’t all making the same adjustments.
But what about the other picture of the dress? This one, that shows the ‘true’ colour? Why did it look different in the other picture even though it was the same dress? As humans we can not see solid objects. All we can see, is light that has interacted with objects. This means, that our light sources have a lot of influence on how we perceive things.
To understand how light interacts with objects we first must understand that light is a part of the electromagnetic spectrum, and has a wavelength. Larger wavelengths, up to 700nm, appear red, and shorter wavelengths, down to 400 nm, appear violet, with the rest of the rainbow resting in between.
There are four different ways light can interact with objects, depending on the molecular structure of the object. Reflection is the bouncing of light. A mirror is a good example of something that reflects most light, depending on its quality, but in fact anything that appears to have a colour is reflecting light of certain wavelengths, namely the wavelengths corresponding to that colour.
If you’re wondering what happens to the rest of the wavelengths, when only specific colours are reflected, the answer is that they are absorbed. Anything that appears black is absorbing all of the light, which is why sometimes people say that black is not a colour. It is what we see when our eyes don’t detect any light. Glass is a material that doesn’t really reflect or absorb light, rather it transmits it, meaning that the light passes through the material unaffected. Similar, but different is how a prism interacts with light. The light passes through the prism, but is bent in the process. Different wavelengths, and thus colours, of light tend to be bent different amounts, which is how prisms create rainbows.
I hope that now you can see that colour isn’t a property material, but rather a type of sum. Original light source, interacting with material, detected by eye, interpreted by brain, equals colour.[/vc_column_text][/vc_column][/vc_row]