Q: Do colors exist?

Physicist: Colors exist in very much the same way that art and love exist.  They can be perceived, and other people will generally understand you if you talk about them, but they don’t really exist in an “out in the world” kind of way.  Although you can make up objective definitions that make things like “green”, “art”, and “love” more real, the definitions are pretty ad-hoc.  Respectively: “green” is light with a wavelength between 520 and 570 nm, “art” is portraits of Elvis on black velvet, and “love” is the smell of napalm in the morning.

But these kinds of definitions merely correspond to the experience of those things, as opposed to actually being those things.  There is certainly a set of wavelengths of light that most people in the world would agree is “red” (rojo, rubrum, rauður, 紅色, أحمر, ruĝa, …).  However, that doesn’t mean that the light itself is red, it just means that a Human brain equipped with Human eyes will label it as red.

You can create an objective definition for green (right), but that’s not really what you mean by “green” (left).

Color is fascinating because, unlike love, its subjectiveness can be easily studied.  We can say, without reservation, that a colorblind person sees colors differently than a colorseeing person.

Different people and animals see color very differently.  The right side is more or less the way most other mammals, as well as red/green colorblind people, see the world.

When a photon (light particle) strikes the back of the eye, whether or not it’s detected depends on what kind of cell it hits and on the wavelength of the light.  We have three kinds of cells, which is pretty good for a mammal, each of which has a different probability of detecting light at various wavelengths.  One of the consequences of this is that we don’t perceive a “true” spectrum.  Instead, our brains have three values to work with, and they create what we think of as color from those.

The three cones cells, and their sensitivity to light of different wavelengths. The dotted line corresponds to the sensitivity of rod cells, which are mostly used for low-light vision.

However, some animals have different kinds of cone cells that allow them to see colors differently, or see wavelengths of light that we don’t see at all.  For example, many insects and birds can see into the near-ultraviolet which is the color we don’t see just beyond purple.  Many birds have ultraviolet plumage, because why not, and many flowering plants use ultraviolet coloration to stand out and direct insects to their pollen.

Left: what people see. Middle: a false-color simulation of what insects may see. Right: a black and white ultraviolet only image

In the deep ocean most animals are blind, or have a very limited range of color sensitivity (it’s as dark as a witch’s something-or-other; what is there to see?).  But some species, like the Black Dragonfish, have taken advantage of that by generating red beams of light that they can see, but that their prey can’t.

The Black Dragonfish cleverly projects red light from those white thingies behind its eyes, which is invisible to its prey.

It may seem strange that some creatures are just “missing” big chucks of the light spectrum, but keep in mind; that’s all of us (people and critters alike).  The visible spectrum (so called, because we can see it), is the brightest part of the Sun’s spectrum.  Since it’s what’s around, life on Earth has evolved to see it (many times!).  But, there is a lot more spectrum out there that no living thing comes close to seeing.

We can see effectively none of the full light spectrum.

Point is, light comes in a lot of different wavelengths, but which wavelengths correspond to which color, or which can even be seen, depends entirely on the eyes of the creature doing the looking, and not really on any property of the light itself.  There isn’t any objective “real” color in the world.  The coloring of the rainbow is nothing more than a shared (reliable, consistent, and kick-ass) illusion.

The lack of objective colorness is a real pain for the science of photography.  Making a substance that becomes (what we call) yellow when it’s exposed to (what we call) yellow light is exactly as difficult as creating a substance that turns magenta when exposed to yellow light.  In a nut-shell, that’s why it took so long for color photography to come along, although there are other theories:

Bill Waterson makes a case for fatherhood.

So, it’s difficult to design film that reacts to light in such a way that we see the colors on the film as “accurate.”  But, in the same sense that yellow may as well be magenta (for all that the film cares), infra-red may as well be red!  You can (were you so motivated) buy infrared sensitive film that photographs light below what we can see, but above what most people call “heat” (the light radiated by warm, but not glowing-hot, objects).

A picture using film that’s sensitive to near-infrared light. This is not a picture of heat (that would use far-infrared), living plants just happen to be infrared-colored.

In fact, most “science pictures” you see: anything with stars, galaxies, individual cells, etc. are “false-color images”.  That is, the cameras detect a form of light that we can’t see (e.g., radiowaves), and then “translate” them into a form we can see.  Which is fine.  If they didn’t, then radio astronomy would be stunningly pointless.

Infrared photo by Richard Mosse.

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18 Responses to Q: Do colors exist?

  1. Lance says:

    There is a shrimp with 16 different color receptors!

    http://www.radiolab.org/2012/may/21/rip-rainbow/

  2. The Physicist The Physicist says:

    Forgot about that radiolab! Well worth listening too.

  3. jayjay says:

    Lofl ! Napalm in the morning! … i ‘love’ a good sense of humor , thanks for the chuckle and the info, as this has been a thought of mine for many years .. a perception of the mind. Very nice site!

  4. John says:

    So ive always wondered, what colour is everything? Not what are brains tell us to differentiate our personal reality, but REALLY what colour is everything. Is everything completely black? or grey? Colours to us are just the stimulation of rods and cones in the eye by light waves, which the brain processes as colours, so colours are an illusion it seems. An evolutionary trick.
    My guess is the world is totally and utterly dark in reality, blacker than black. Yes there are light waves tearing around, eyes are just tools to sense it and make `something` of it. Does that make any sense?

  5. Freya says:

    I think you hit the nail on the head there, John. It scares me to think that our brains perceive an accurate picture of reality but not truly reality.

  6. james says:

    The better question is WHO sees the color?

    Many people like to envision themselves as peeking through holes in their skull to see the real world but we know thats not true. If the photons hit the eye and are converted to signals and sent to the mind–where is the image viewed? Who views it—there is no real light inside the dark skull.
    is there a “me” inside who sees it on a screen of some sorts? There is infinite regress of selfs if so. There is no way science can answer this question. If the mind is just viewed as a computer–then just as there is no one inside the computer to see the images that we see on the monitor–then there is also no one inside our brains.

    Interestingly, atheist science has denied absolutely all the things we know are true about ourselves. There has to be a self behind the mind or no one can “see”. There has to be freewill for me to type even one word here without it looking like this jhf8wu f]w=0f9n 8f ue8fj .

    In this rush to confirm their worst fear–that there is Creator–they have denied they are even real. That they have a logical opinion. Multiverse, Matrix etc..anything to deny what every culture on earth has known for all of history.

  7. Mike says:

    First of all, atheism is the lack of belief in God, nothing more. I am sure there are atheists who do believe in the soul, free will, etc. Even if you are right, and there is a ‘self’ behind the eyes, it’s still a leap to conclude that a Creator put it there. How do you justify that logic leap? One could argue that the atheist position could theoretically be more in favour of the free will position, anyway – surely there is more determinism in a universe governed by an all-powerful, omniscient God? I’m sure you’ve heard many Christians ponder about “God’s plan” for them; well, atheists don’t have plans mapped out for them. I don’t claim to speak for all atheists – many would dispute the definition of ‘free will’ I’m using here – but I’d like you to be aware that atheism doesn’t automatically denote nonbelief in free will and other philosophical and spiritual concepts that are not directly related to the issue of Creationism.

    The brain is a computer. There is no ‘self’ ‘inside’ the computer; the self is the product of the computer. If I were to strike you in the skull with a hammer (which I don’t want to, but bear with me!) and cause you severe brain damage, reducing you to a vegetable-like mental state, in a sense you wouldn’t be ‘you’ any more. The things that make your ‘self’ what it is – personality, higher reasoning, memories, etc – would be lost with the destruction of the brain.

    Even if it were true, though, that scientists have decided that they themselves “aren’t real” – well, so what? Your argument is starting to go round in circles. Who are you arguing with, then? You might want to back up a little bit and reevaluate some of what you’re saying. :)

  8. Larry Dale says:

    Okay, Mike let’s look at it another way. What about the martial Artist’s Chi? I am a long time martial artist and I can tell you that many do not see the brain as the reservoir for a soul, spirit (whatever you prefer). Destroying the brain is a matter of the destroying one of the vtial points thus interupting the flow of energy. Our body is made up of specific units and minus any one of them and we die. The heart is not a brain yet no matter what the brian issues if the heart has stopped….The ‘life energy’ is not a product of the brain alone but a mixture of ‘signals’ which in the end is as unique as the individual carrying it.
    Biocentrism might also disagree with your statements.

  9. crumplehorn says:

    Thanks Physicist, I liked the way you explained this. How do the substances/objects of the world absorb and reflect light in different ways in order to project waves that we perceive as different colours? Although it is my brain that interprets the light waves perceived by my eyes, how do objects consistently reflect the same light waves for me to see and why do they? Am I confusing things here (should I adopt Hobbes’s postion?!)…

  10. Ammar Khan says:

    That was definitely something I’d call food for thought. But this ideology that objects absorb light and reflect whatever they cannot absorb and then finally our eyes detect them as “colours” as they are designed to. Is it true? Other creatures may see them in a different way, but that’s a different discussion. The questions is, everything is “coloured” because of it’s ability to absorb light and reflect it on different angles and because of that particular reason the light they reflect, we detect them as colours?
    So basically it’s just the nature of substance and it’s structure that determines an object’s “colour”, is it?
    God! Please do clearify, it’s bitting me.

  11. Gus says:

    Why do chamaleons bother changing color if it doesn’t exist?

  12. The Physicist The Physicist says:

    Because in the most important sense (that predators can see them) colors exist.

  13. Dionlevy says:

    MIKE,

    I’m sure you don’t check this site that I Just stumbled upon. I am Glad that you mentioned computers, because I have some understanding as I fixed many of my brothers and friends computers, when they had hardware and software problems. Computers are perhaps the best thing to relate to the human mind. While they are also the best example to prove intelligent design. My argument will be very short.

    Firstly, I don’t agree with James, although I do understand the path of reasoning he took. I believe that you and I share common truths, and computers doesn’t need a “inner self” to process information. That information is processed in the processor, in humans case the brain.

    Here is my argument. Humans (or as you state human brains), are complex computers.
    All computers have a creator.
    Therefore, Humans have a creator.

  14. LarryD says:

    The definition of a ‘computer’ is a programmable MACHINE. So you proceed from a false assumption!

  15. stanley says:

    Nice article but im curious if colour is only something perceived and doesnt actually exist, then what abour colour pigmentation? What about objects absorbing light and then reflecting what hasnt been absorbed as a certain colour. Is there no subatomic play happening here?

  16. Dogmosis says:

    So I don’t believe that color only exists within the mind.. All this is is a rehash of the age old “If a tree falls in the forest” thought experiment and I am one to say that it does make a sound. This whole “does something exist without an observer” mindset is lame to me. Color exists outside our minds and if you have doubts, all you need to do is ask yourself if color didn’t exist, then why did color vision evolve? There needed to be water for fish to evolve, there needed to be land for fish to evolve into amphibians on up, there needed to be air for wings to evolve, there needed to be things to see for eyes to evolve.. and so on. Just like there needed to be color in the world for color vision to evolve. That’s how evolution works, adapting to what is there..

    That doesn’t mean color isn’t subjective.. it’s neither subjective or objective really, it’s relative. Relative to your biological hardware that evolved to see color. Such as your cone cells.. If you have more red cones than someone else, you’re going to be able to see more shades of red. If you’re lacking green cones, you’re not going to be able to see green.

    That’s how light works.. It strikes an object and reflects back the corresponding wave length. Infrared and UV light waves are not light waves that interact with an object’s color, rather other properties. Such as a flower petal having a surface that is able to reflect UV light.

    And your cone cells have actual pigment in them.. Red pigment in red cones, green in green cones, and blue pigment in blue cones. Each individual cone cell has countless pigments in it, each with varying degrees of concentration. So when you’re looking at some green grass, sunlight is hitting it and reflecting back a very specific wave length. The grass is green, but the light wave reflected back isn’t actually green in color, but it will only be able to pass through a specific concentration of green pigment in a green cone cell.. and when it passing through that, it sends the color to your brain. If you don’t have any green cone cells, there will be no green pigment to allow the light wave that corresponds to green to pass through. So there is green color to grass, a colorless light wave reflected back that corresponds to green, and then green pigment in your cone cells that matches the light wave reflected back by the grass that sends the green color to your brain for processing with the rest of the image.

    So to me, color exists out in the world.. but how we perceive it is relative. Luckily for us, through our evolution we’ve developed full color vision. Although, your brain can really jack up the signals being interpreted.. such as synesthesia, that’s no reason to believe that your brain is creating more than it is interpreting.

  17. Dogmosis says:

    And there is some illusion in color.. such as blue skies, blue eyes, neon lights, sunsets and rises, fire could probably be considered one. A blue sky is an illusion because all it is is scattered light waves, light waves that correspond to blue.. Neon lights only excite gas into a plasma light state that sends out specific light waves, it’s not like the gas is actually that color.

    But to think that all color is an illusion is not seeing the bigger picture imo.

  18. Dan Jacob says:

    Not only are colors non-existent, but brightness and darkness don’t exist either. It isn’t bright under a blazing sun, and a moonless night isn’t dark.

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