I always learned “ROYGBIV” as the colors of the rainbow. Red, orange, yellow, blue, indigo, violet.

What’s up with the last two? Isn’t indigo basically just dark blue? Why is it violet and not purple? Can’t it just be “ROYGBP”?

    • DrQuint@lemmy.world
      0·
      1 year ago

      Actually…

      There is no purple light.

      Kinda.

      Video explaining it in detail: https://youtu.be/CoLQF3cfxv0

      Several colors we can perceive only exist as a specific mixture of wavelengths. And purple (coincidentally for this thread) is one such - white light contains it, sure, but, you can’t isolate it to a specific single band, like you can isolate cyan or yellow. So, no, rainbows can not have purple in them.

      • FiskFisk33@lemmy.world
        0·
        1 year ago

        I disagree. That color he keeps talking about is magenta, there is no magenta light. I see purple in the rainbow, but not magenta.

        • Dr Cog@mander.xyz
          0·
          1 year ago

          You would be half correct. Magenta is impossible “in the real world”. It obviously exists on your computer screen due to its ability to shoot colored light into your eyeballs

    • floofloof@lemmy.ca
      0·
      1 year ago

      It doesn’t contain pink or brown. Some of the colours we see are how we register a mixture of light frequencies, whereas each point in the rainbow is just a single frequency.

      • Rexelpitlum@discuss.tchncs.de
        0·
        1 year ago

        What a phantastic thread!

        We have had linguistics, sociology, physics and now biology in the form of colour perception so far.

        Cross domain discussions are great! :-)

      • Dr Cog@mander.xyz
        0·
        1 year ago

        This is incredibly incorrect. While many colors that are additive are combinations, those combinations are simply approximations of the single wavelength true color. All colors are on a spectrum of hue, luminance (brightness) and intensity (saturation).

        Pink is red with high luminance and high intensity, and brown is orange with low luminance and mid-high intensity

    • Thassar@lemmy.blahaj.zone
      0·
      1 year ago

      You’d think so but colours are weird. Some of the ones we see aren’t ones that actually exist, they’re invented by our brains. Magenta for example doesn’t exist, there is no wavelength for it and because of the way our eyes detect light it should really be a shade of green. But our brain doesn’t like that and invents a brand new colour instead.

    • mookulator@wirebase.orgOP
      0·
      1 year ago

      Well yeah. I guess my question should be “why do we learn indigo and violet when we learn about the rainbow”. It’s more cultural

      • Rexelpitlum@discuss.tchncs.de
        0·
        1 year ago

        Yes, exactly.

        E.g. in Germany I don’t have heard anyone using Indigo and Purpur as major colours but only in combination with blue : “Purpurblau” and “Indigoblau” describing certain forms of blue.

        So only blue and violet in german rainbows. And ultraviolet because most of us are more engineer than poet nowadays ;-)

    • Dewbs84@lemmy.fmhy.ml
      0·
      1 year ago

      Well yes, but the differentiation of colors varies by, believe it or not, culture! For example, the Japanese word for blue, 青 (ao) was used both (depending on context) for what we would call blue and green, and it wasn’t until modern times that a new word, 緑 (midori) started being used to explicitly define what we might call green. Even now, their ‘green’ traffic lights would be described as blue in other cultures. My apologies for the euro-centric over-simplification, but here’s a great article to elaborate further: https://cotoacademy.com/japanese-color-blue-green-aoi-midori-青い-みどり/