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Purple exists only in our brains
- croddin 2y agoThis is equivalent to saying a C Major chord only exists in our brains since it isn't a note.
- o_nate 2y agoIt seems reasonable to me to say that soundwaves exist in the world, but music only exists in our brains. There is something added in our perception of the soundwaves that turns them into music.
- 9rx 2y agoSomething exits in the world, it seems. Sound waves and music are merely our interpretation of it. Maybe what actually exists in the world is music, and sound waves are what our brain invents when the music is too complex for it to grasp?
- o_nate 2y agoI guess my point is that sound waves are not terribly controversial. A simple device can measure sound waves present in the air. It would be much more difficult to build a device that told you whether music was playing. Reasonable people could disagree about whether certain sound waves constitute music or noise.
- beardyw 2y agoWell if we get on to hearing, our ears do a lot better than our eyes. From the source entering into hole on either side of our head we can split the sound into a myriad of frequencies and gather a lot of information from it. In a similar situation from a single point of light out eyes would say "sort of blue-ish". Most visible frequency information is ignored.
- automatic6131 2y agoMore than purple not existing, brown really doesn't exist. Brown is just reflected orange-y light in the right context. You can play around with it, by looking at a picture of say, earthy soil, color picking that pixel and painting it on a white canvas in a different way. Or by trying to shine an RGB light with that color code. It will look orange in a direct light. Also the purple hallucination is because the same cone that mostly detects red also has a small peak futher along the spectrum next to blue. Since it slightly reacts to blue/violet light, you get that purple tickle.
- latexr 2y agoTechnology connections made a video on it. https://www.youtube.com/watch?v=wh4aWZRtTwU https://www.youtube.com/watch?v=wh4aWZRtTwU
- LuciOfStars 2y agoCame here looking for this haha, Alec's videos are always a treat.
- automatic6131 2y agoThank you, I couldn't remember who made it, thought it was Knowing Better for some reason
- masfuerte 2y agoAccording to this [1] that extra bump is a myth. But I'm not qualified to judge. [1]: https://physics.stackexchange.com/questions/673991/red-cones-spectral-sensitivity https://physics.stackexchange.com/questions/673991/red-cones...
- hnuser123456 2y agoI wonder if near-UV like 380nm starts exciting the red receptor at 760nm like a resonant frequency or harmonic. Would also explain why something that's deeply red enough doesn't start looking purple, because the lower-energy photons can't get the higher energy receptors to trigger, unlike the other way around for deep blue. Which would make the color purple a distinctly quantum phenomenon.
- bryanlarsen 2y agoI love the headline, but unfortunately both the headline and the explanation are wrong. Better explanation: The red, green and blue receptors in the eyes all respond to all wavelengths of light, they're just more sensitive at red, green and blue respectively. When violet hits those receptors, it doesn't hit any of the receptors at their peak sensitivity point. All three receptors fire. However, the green receptor has much better sensitivity than the red receptor, so violet triggers the strongest response in blue and red. If the red receptor was more sensitive, we'd probably interpret violet as a shade of blueish-brown rather than of purple. The headline: Purple definitely exists. The eye & brain interpret purple and violet the same, but in the physical world they are different colors, and they both exist in the wild. Purple is a mixture of red & blue, violet is the highest visible frequency. A purple flower is a flower that absorbs green and reflects red & blue. A violet flower is a flower that absorbs red, green and blue and reflects violet.
- AlotOfReading 2y agoColors like purple are called "extraspectral" to distinguish them from the spectral colors like violet.
- Anon84 2y agoSame with pink.
- bryanlarsen 2y agoP.S. Tetrachromats can distinguish between violet and purple, unlike us normal humans.
- stvltvs 2y agoNot true. Human tetrachromats have an extra kind of receptor somewhere between the blue and red receptors' sensitivity. This doesn't help with colors like violet that are outside of that range. Also, purple (a non-spectral color) is easily distinguished from violet (a spectral color) if you see them side-by-side.
- moktonar 2y agoWell.. no color “exists”, they are just wave like particles.. not even “reality” as we see it exists.. it’s just in our minds.. I think that what they really mean is that there is no wavelength for the purple we see
- sandworm101 2y agoExcept for colors that are combinations of different, disconnected, wavelengths. This is why there are red and blue stars, but no green or magenta stars.
- anamexis 2y agoThat's not really the reason. Green is a spectral color, and in fact the sun peaks around the green part of the spectrum. But to see a star as green, it would need to exclusively emit green light.
- esafak 2y agoI understand it more intuitively from a chromaticity diagram, depicting color divorced from brightness: https://en.wikipedia.org/wiki/Purple#/media/File:Line_of_purples.png https://en.wikipedia.org/wiki/Purple#/media/File:Line_of_pur... The curved rim of the horseshoe is the spectral locus; that of the purest, single wavelength spectral colors. Purples are what you get when you travel between the ends of the horseshoe, where no spectral color lies. This is what is meant when one says purple exists only in our brains; it is non-spectral. Furthermore, our vision is such that objectively different spectra can look the same; cf. metamers. This follows from the fact that the process of projecting an infinite dimensional spectra into three dimensions (because color is 3D) is lossy. But our vision optimizes the dimension reduction for spectral discrimination in parts of the electromagnetic spectrum that are beneficial for evolution.
- perihelions 2y agoThe spectral locus is highlighted in this one (for clarity), https://en.wikipedia.org/wiki/CIE_1931_color_space#Chromaticity_diagram https://en.wikipedia.org/wiki/CIE_1931_color_space#Chromatic... That outer *bolded* edge is monochromatic light, as perceived by humans. The number labels are the wavelength in nanometers.
- esafak 2y agoI forgot to add that in addition to being non-spectral, they are the most saturated colors of their hue. All colors inside the horseshoe are non-spectral; they are mixtures of spectral colors. https://en.wikipedia.org/wiki/Line_of_purples https://en.wikipedia.org/wiki/Line_of_purples
- temporallobe 2y agoThis is silly. Everything exists “only in our brains”. The ancient Greeks knew this - see Plato’s Allegory of the Cave.
- 4ndrewl 2y agoYou don't only exist in my brain.
- dboreham 2y agoThe article says this (and pretty much all the other comments here). It doesn't however mention James Clerk Maxwell who took a break from inventing equations to torture EE students forever to figure this stuff out, including making the first color photograph. (Yes I know Heaviside actually came up with the equations we use)
- JohnMakin 2y ago> There is something unique about the color purple: Our brain makes it up. So you might just call purple a pigment of our imagination. You know, in the past, my curmudgeonly self would have rankled at a pun like this in a science article, but I don't think AI slop could come up with this, it's pretty good.
- empath75 2y agome: for a science article come up with a pun about purple being imaginary ChatGPT said: "Purple: Just a pigment of your imagination." --- me: For a pop science article: finish this sentence with a pun There is something unique about the color purple: Our brain makes it up. So you might just call purple a 2/2 ChatGPT said: pigment of your imagination. --- me: For a pop science article about the color purple being imaginary, write an opening paragraph with some punning word play... ChatGPT said: Purple is a pigment of our imagination—quite literally. Violet may bloom in nature, and red and blue dance on opposite ends of the rainbow, but purple itself is royally absent from the spectrum's party. Instead, it's a chromatic concoction our brains whip up to bridge a colorful gap, making purple less of a wavelength and more of a wave-lengthy illusion. So, the next time you spot lavender fields or don a plum-colored sweater, remember: you're seeing something that's vividly not there. (all of these were separate clean contexts with chatgpt 4.5)
- bqmjjx0kac 2y agoSadly, these clean contexts also include vast swathes of the internet. I bet someone already came up with "pigment of your imagination".
- empath75 2y agoI was responding to the parent argument that the pun couldn't have been written by chatgpt, when that is literally the _only_ pun that ChatGPT comes up with.
- turnsout 2y agoI mean, all colors exist only in our brains. "Color" is a perceptual experience that may start as spectral power and cone excitation, but is then mapped to color sensation through a fantastically complex visual system in the brain. That's why color-based optical illusions work. That's why "The Dress" was controversial. There's nothing that special about purple. The article makes a big deal about purple "connecting" two opposite ends of the spectrum, but this is just an artifact of humans seeing rainbows and realizing that pink-purple would connect the two ends, even if they're not present in the rainbow. It's just a human framework, not some kind of physical truth. Put another way, there are a ton of colors that are not in the rainbow, because it's a 1D simplification of our color perception, which is 3D (three cones). Would you say brown "exists only in our brains?"
- larrik 2y agoThe visible spectrum is the range of wavelengths of light our eyes can detect. I mean, that sounds nice, but pink, brown, white, and black clearly aren't on that spectrum, so it's a ton more complicated than that, eh? Of those 4, only "white" is mentioned at all in the article.
- d--b 2y agoCome on guys, read yourselves. The article is pretty good and to everyone not well versed in colors and wavelengths, it is very interesting and well phrased.
- igouy 2y agoAttention economy -- dismiss apparent flaws asap. Not "Purple exists only in our brains" instead " “All colors are made up by the brain. Full stop,” says this visual scientist"
- yaky 2y agoFun fact: such "purples" exist for other species. There was a study that found that hummingbirds are more attracted to a color that is a mix of green and ultraviolet (imperceptible to humans, but similar to our concept of "purple"), than just green, violet, or ultraviolet.
- tomxor 2y agoPretty stupid to label something "not real" just because it's not a pure spectral colour. I guess white isn't "real" either.
- FollowingTheDao 2y agoOur brain makes up every color. Color does not exist. Wavelengths exist, but color does not. Our brains turn the wavelengths we see into colors. Everything is a wave.
- bryanlarsen 2y agoDoes 700 nm wavelength light exist? If so, so does red.
- NickM 2y agoThe article is flat out wrong. The reason purple and violet look similar is not a trick of the brain, and has nothing to do with the color wheel "wrapping around"; it's a natural result of the frequency response curves of the three types of cones in our eyes. The two colors stimulate our cones in the same way, so of course they naturally look similar. Most diagrams of our cone frequency responses are subtly wrong. Diagrams typically show three separate smooth, overlapping peaks, centered around red, green, and blue. What they leave out is that our L-cones (the "red" cones) also have a separate little sensitivity bump way off in the violet end of the spectrum. So when you see violet light, it's actually stimulating both the cones that are most sensitive to red light and the ones that are sensitive to blue light. This is pretty much the same stimulation pattern you get if you send both pure red and blue light into your eyes together, which is why purple and violet look so similar. If you Google "cone sensitivity diagram" you'll mostly find the misleading versions of the diagrams, but you can see one that includes the extra bit of high-frequency L-cone sensitivity in this paper, for example: https://hal.science/hal-01565649/file/Vienot_ConeFundamentalsModelFutureColorimetry_LRT2016%20(1).pdf https://hal.science/hal-01565649/file/Vienot_ConeFundamental...
- igouy 2y agoColor "exists only in our brains". "It is common to say that certain wave lengths of the electromagnetic spectrum are a given color, but in truth, it is more correct to say that those stimuli are perceived to be of a certain color when viewed under specific conditions. So without the human observer, there is really no color, and practical standards for color must take this factor of human perception into account." "Charting Color from the Eye of the Beholder" 2005 https://www.americanscientist.org/article/charting-color-from-the-eye-of-the-beholder https://www.americanscientist.org/article/charting-color-fro...