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we don't really see the raw light we only see what is bounced back to us. our eyes are not deceiving us because they are working the way they should be but it's more our perception of light which can be misleading. kind of like saying the sun rises and falls daily because that's what we see but in reality, we are moving around the sun, not the sun around us.
Color describes a qualitative experience in a way that wavelength doesn't. All the mechanics of prisms and cones can be described in terms of wavelength alone. But raw Hz numbers fail to "paint the picture" of human experience. So I find the terms only partly interchangeable.
There's a direct relationship between frequency and wavelength, and an approximate relationship between frequency or wavelength and colour. The colours we perceive are modified by other factors, such as illumination hue and intensity, perceived adjacent colours, memory, and expectation.
But doesn't this beg the question...what about the rest of the electromagnetic spectrum? Why does just this miniscule little swath of it get to be light/color while the rest of it we interpret as something else entirely? Isn't it simply our eyes in tandem with our brain that are making this differentiation?
Our eyes have evolved to detect just a small part of the electromagnetic spectrum, presumably a compromise between utility and feasibility.
Well, yes, of course. Perceptions are mental representations of sensory input. They all enter the brain as neural spike trains and are interpreted according to their sensory source. IIRC the closest representation to the incoming stimuli is the auditory pathway, where the spike trains have the same frequencies as the sound stimuli (I can't vouch for the accuracy of this memory!).
To me that's just a really fun photo to illuminate a fun topic that is very enjoyable to discuss: how well does visual perception work and what are its limits and such, as you helpfully opened up.
It's interesting, expose your eyes to the correct level of electromagnetic radiation and you'll probably fry them like a grape in a microwave. Lower the wavelength a bit and you'll just see pretty colors. On the other hand go out and stare at the sun for awhile and maybe you'll get to see it dance. Then you can experience your own personal miracle, just like Fatima.Or maybe this readout instead of the above...
(A Geiger counter maxes out at 999,000 counts per minute on a narrow spot on the ground close to where equipment contaminated with radioactivity lay strewn in the ghost town of Pripyat not far from the Chernobyl nuclear power plant on August 18, 2017 (Photo: Sean Gallup/Getty Images)
The long-term effects of the Chernobyl disaster
At which point I think I'd move back, maybe more than just a few steps, and continue checking, until I noticed a more normal lower reading.
Dreams are one thing. A whole topic even. Even trances and visions and so on, (which don't need physical light at all, and often have historically been done in dark caves and other places designed to reduce visual input).
Thanks for the compliment
Phenomenology can be fascinating - Hegel apart...
Because contrary to the idea asked about in the OP of the thread (to which you were responding), there is a firm external reality, and we can gradually see it with our eyes even (with time and effort), and that's not an illusion, even though our perception does tend to fall into illusions for a time sometimes. So, the significant point is that even though we see through a glass darkly or such, we can actually see something that is real in a manner, and that isn't illusion in the end.Thanks for the compliment
But I'm afraid I don't get it - why is a picture of an electronic meter a fun photo in this context? Is it just that it tells us things our eyes can't see?
Wavelength is an intrinsic property for colour in light; this is the physics definition.
An interesting discovery in recent years is that you can fit out humans with kit that stimulates touch sensors in various ways that vary according to what objects are around them or the direction they're facing (e.g. a belt that vibrates in different places along its length to indicate a particular direction, or a tongue pad with a grid of pins that move in and out to indicate shapes in front or behind, etc.). When people become accustomed to these extra 'senses', they may find they become integrated into their visual perception. IOW, brain plasticity allows certain sensory inputs to be re-routed and reinterpreted into a different perceptual modality.
This is only part of the story as astronomy opens up a different field.
None of that touches the experience (rather than the mechanics) of color perception tho, which relates to the OP question.
If enough people can agree on the test method and thence on what to call the colour of the resultant, then that colour can be regarded as objectified. Once objectified, it can be assigned as being a property of some (other) object, by following that same process.
We generally agree on a test method for the wavelength of a red stop light. But do we agree on a test to determine whether your subjective experience of red matches a. what other people experience, and b. any objective property of the light?
That only works up to a point. Remember 'that dress'?
The problem is more than just an inability to compare subjective experiences. The larger problem is whether color is an attribute of reality at all. Or is color simply our mind's way of representing specific wavelengths of light? Admittedly it's a very effective method of depicting a continuous spectrum, but even if we all agree about the color of a stoplight, that doesn't make "red" anything more than just a mental representation of a specific wavelength.
Not exactly; colours are mental representations of the world based on wavelengths of light; what we perceive is adjusted for colour constancy according to expectations based on past experience, so we might perceive the same wavelengths differently depending on the context. We only agree on the colour of a stoplight because the frequencies of its light are similar to the frequencies of light from other things that we call red.
There's neither wavelength nor colour in the brain, just neurons firing in patterns. It's been shown that the output of a small groups of cells in the visual cortex (the Hurvich–Jameson (H–J) opponent-process network) determines the perceived colour, and it's possible to manipulate the visual input to these cells so as to produce outputs that are outside the normal/natural range of outputs, and so enable the perception of colours that you wouldn't otherwise see (Chimerical Colors: Some Phenomenological Predictions from Cognitive Neuroscience by Paul Churchland - I have a pre-paywall copy of the PDF if you're interested).
It's only red because that's what we call the colour of things that match it visually. People with various forms of colour-blindness, and tetrachromats, will see a greater or smaller range of colours than normal, so won't always even agree on what matches and what doesn't...
