-
Asked by hear1dote to Stefan, nikrobinson, Lena, jesshawkins, Christina, Barbara on 1 Jul 2024.
-
Nik Robinson answered on 1 Jul 2024:
This is an intersting question nad philosophical in a way.
How do we know that what I see as blue is the same as what you see as blue?
In fact those with colour blindness and defects, we know see things differently.
What we do know is that the area of the spectrum we describe as blue represents light in the wavelength range of 450 and 495 nanometers.
The word Blue comes form french, but why the word was associated with this part of the electro magnetic spectrum I do not know.
-
Comments
Luke commented on :
Colour theory is a multi-disciplinary rabbit hole from which you may never emerge. The intersection of clean fundamentals of optical physics with the messy realities of evolutionary biology, anthropology, art, and linguistics. Be wary.
Photons have wavelength according to energy. High wavelength, low energy.
The sun emits a broad spectrum of photon wavelengths, more than what we can see. This includes things we don’t always refer to as “light”: radio waves, X-rays, gamma-rays, microwaves, etc.
Most of these wavelengths are attenuated by the Earth’s atmosphere. Some make it through.
Of those that do, there is a continuous band which life on Earth evolved to be able to see. The exact range varies by creature.
For humans, we can see the spectrum we call “visible light”. Fundamentally, this is a linear spectrum from 380 to 700 nanometers.
The number of primary colours also varies by creature.
Humans have three cones in our eyes. Thus we have three primary colours: red, blue, and yellow.
Butterflys have 15 cones, their experience of colour is unimaginable.
Dogs have 2 cones, what we call red and green look the same to dogs.
If you want a dog to be able to see it’s ball on the green grass, a blue is the ideal colour to choose.
Now that we have eyes and brains involved, things get weird. Even though red and purple are at opposite ends of the spectrum, they blend together in our minds. The spectrum becomes a wheel.
We did not evolve to see the world as it really is. We evolved to stay alive. Our vision is logarithmic, exaggerating contrasts to maximise the chances of detecting changes in our environment. The brain uses context to streamline the experience, showing you the colours it thinks should be there, rather than what is really there, in the hopes of giving you faster reaction times. Optical illusions can reveal these weird quirks of vision.
At any given time, you’re actually getting many different wavelengths hitting your eyes. The brain finds the average. Plants look green because they mostly reflect green light, but also because they mostly absorb blue light, opposite green on the colour wheel.
Light’s wavelength is a fundamental physical concept. Colour is what we see when our brains are done processing it.
Because colour is so closely linked to our evolution, there is an interesting phenomenon where almost all cultures on Earth independantly name the colours in the same order: black and white first, then red, green, yellow and blue.
Despite being a primary colour, and the colour of the sky, blue comes quite late in the process. Usually, people use the word for green to describe the colour of the sky, until a word for blue has emerged.
So the answer is, we named Blue once we needed a name for it. Before that, it was probably called Green. Of course, this would have been long before modern English, so the actual words were probably something different in each of the various language groups that converged to make English: romantic, germanic, gaelic, etc.
Sidenote: Blue also means sad in English. Is there something fundamental that makes us associate the colour with sadness? Or is it just a coincidence?
Pete Webb commented on :
Why the colour blue came to be called “blue” is unknown, because there is no written record of how that and the many other words that Homo sapiens sapiens’ ancestors needed in order to communicate effectively were introduced into their daily activities. The colour blue might have been rendered as “glik”, or “snilv”, we’ll just never know. But at some stage, “blue” became accepted by English speakers. Note that blue is blau in German and bleu in French, both quite similar to blue, but it’s azul in Spanish and abi in Farsi (Persian), so there’s obviously no globally accepted word, each word evolved in its own regional and cultural context.