First of all, I don’t understand why indigo and violet are split… why not just call it purple? Ok, not my question.
Colors of the rainbow all make sense to me except purple.
Red – orange – yellow…makes sense that orange is between red and yellow, and it’s the combination of those two primary colors, nice transition
This follows with green, blue. Green is between yellow and blue.
Now… if purple aka indigo and violet are a combination of blue and red, how can it be on the opposite end of red (very different frequency) and outside the frequency range of blue? I would expect a secondary color’s frequency to be between the two primary colors that create it
In: 76
Purple is a special colour, it’s not a pure colour with one frequency, it is a mixture of both red and blue(or indigo or violet).
When you mix these colours from the opposite ends of the spectrum they don’t average out to produce green but the unique colour purple.
Purple, as light, is a lie, your brain being confused about what it’s seeing. The color wheel is a convenient way to organize color, but it’s not some sort of definitive 100% factual construct.
[https://www.youtube.com/watch?v=CoLQF3cfxv0](https://www.youtube.com/watch?v=CoLQF3cfxv0)
[https://grantsonnex.com/why-purple-doesnt-exist/](https://grantsonnex.com/why-purple-doesnt-exist/)
> First of all, I don’t understand why indigo and violet are split
When the ROY G BIV acronym was first used, “blue” meant something closer to “cyan”, and “indigo” really meant “blue”.
As for your main question, red yellow and blue are *not* the so-called “primary colours”. Depending on what you mean, primary colours are *either* red green blue (RGB) or cyan yellow magenta (CMY). These primary colours have to do with how our eyes actually see colour and how coloured light can be combined to create other colours.
RGB are the “additive” primary colours, which you can sort of think of as being the true primary colours. These are important when you’re producing light, like in computer monitors. Your eyes have three types of light detecting cells, each of which is more sensitive to one of those three colours. Red light will excite your red cone cells much more than your green or blue cone cells, etc. Combining any two of these colours creates a colour from the CMY set. For example, combining red light with blue light will appear magenta. Combining green light with blue light with appear cyan.
CMY are the “subtractive” primary colours, which are important when you’re combining pigments (e.g. mixing paint). These are the real primary colours that you should think of when you think of physically mixing colours together. What’s happening is this: A pigment having light shone on it absorbs some of that light and then reflects the rest back to your eyes, which is what you see. A cyan pigment *removes red light* and reflects back to your eyes a mixture of blue and green. A yellow pigment *removes blue light* and reflects back green and red. If you combine yellow with cyan, you combine their absorption, so the mixed pigment will absorb both red and blue, leaving you with green.
“Purple” can either refer to something close to magenta, which is not one frequency of light but is just how your eyes interpret both red and blue together, or it can be something closer to the deep violet in the rainbow, which is a very high frequency of visible light.
Purple IS between red and blue, if you arrange the colours around a circle:
[https://en.wikipedia.org/wiki/Visible_spectrum#/media/File:Newton’s_color_circle.png](https://en.wikipedia.org/wiki/Visible_spectrum#/media/File:Newton’s_color_circle.png)
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Say red may be 680nm, blue may be 470nm. The “average” of these is 575nm, which can’t be purple since it’s already taken by yellow.
Purple, or maybe more accurately magenta and pink, is our brain’s way of seeing the absence of green in the presence of other frequencies. We have three types of color sensing cells that get excited the most when light of a certain frequency hits them, they roughly correspond to red, green, and blue. Any color that consists of light at a single frequency will excite either red more than green more than blue (that’s how RGB lights can simulate yellow by emitting red and green, even though they don’t emit the yellow frequency at all), or blue more than green more than red, or green more than both blue and red. Magenta happens when blue and red are excited more than green.
So, when we look at the extreme ends of the spectrum, they look a little similar because neither end excites the green cells much.
You are confusing the color theory of how paints mixed together with the color theory of how light works.
[Color is light vibrating at different frequencies. ](https://evokasydney.com/wp-content/uploads/2020/07/visible-spectrum.jpg)
All of the red that you see is hitting you like a bear hug that slowly becomes a person napping on your shoulders. Red has the lowest frequency and ironically produces the least amount of energy. This is why middle-aged stars are red. That plain old fire that you’re looking at in a fireplace is actually the weakest fire possible. Weak sauce fire. [Get you some of that blue fire. ](https://sciencenotes.org/wp-content/uploads/2022/04/The-Colors-of-Stars-From-Hottest-to-Coldest.png) That’s the hot stuff.
All of the violet you see is hitting you like a triple-slap in the face. Violet has the highest frequency and produces the highest amount of energy that we are still able to see with our eyes.
Paint and pigment, both found in nature and artificial, has convinced you that there is such a thing as magenta and purple exist. [Magenta and purple are not real. ](https://www.kooslooijesteijn.net/generated/assets/blog/2017-04-14/red-magenta-purple-violet-800-571fffeef.png) Violet is the word we use to describe the actual color that we see from light. Purple and magenta are the 2nd Place prize our brain gives us when we see red and blue at the same time.
Don’t be sad, though, our brain also gets messed up if it sees too much orange or sees neon yellow and navy blue. [Here, stare at these pictures. ](https://miro.medium.com/v2/resize:fit:1400/1*8bIUN8MZ11NODRTyuB1IUg.jpeg)
Indigo is there because the guy who originally theorised the spectrum was obsessed with the number 7 and believed that all of nature fell into groups of 7 as some sort of mystical number
The chemicals in your retina that detect violet and blue are similar to the ones that detect red, not to the ones that detect green, yellow or orange. Primates don’t have to tell apart more than six colours, we could do with even less.
That’s how evolution works: whatever works, stays like that in the next generation unless small variations work reasonably better.
Light that we would call purple (indigo /violet) has a shorter wavelength than all the other colors, that’s why it’s at the end of the rainbow. Purple being made by mixing blue and red is because of how our eyes work, there’s no purple receptor, only r, g, b and we interpret colors based on how much they excite each of those.
One simplistic way to think of is it to put the colours on a pie chart or around a tube, where the ends of the spectrum meet. Our eyes see both ends of the spectrum as somewhat similar. So at one end you have red, and at the other end you have almost come around to red again.
Or you could think of the spectrum as akin to musical octave. You have a “C” or whatever at the bottom and a Bb (almost C) at the top. Red has almost exactly double the wave length of violet, so red and violet may somewhat be perceived as similar by our retinal receptors, just like middle C and high C sound weirdly alike to our ears.
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