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With light poise and counter-poise, Nature oscillates within prescribed limits. Yet thus all arise the varieties and conditions of the phenomena which are present to us in space and time. - Goethe

The touchstone of Newton's theory was his famous experiment with the prism. A prism breaks a beam of white light into a rainbow of colors, spread across a whole visible spectrum. Then Newton realized that must be the elementary components that add up to create white.

While Newton used the standard prism, and passed white light through it, Goethe had also run a series of experiments, with a prism again, but by just looking through the prism.

And he found everything uniform, but when his prism passed through the fold of a cloud behind the sun, he was met with a blast of color, where he stated that 'color is the interchange of light and shadow.'

Goethe's ideas resemble a facile notion, popular among psychologists, but Feigenbaum argued that his Goethe's) statement had true science in them which emphasized the peatability of his experiments.

It was the perception of color, to both Goethe and Feigenbaum, that was universal and objective.

So in that sense, what scientific evidence is there for the definable real world quality of redness independent our perception?

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    $\begingroup$ I’m voting to close this question because it is asking about colour perception, which is psychology or philosophy not physics. Redness is a concept of mind, not a physical concept. Perhaps Psychology & neuroscience would be more suitable. $\endgroup$ – sammy gerbil May 4 at 8:52
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    $\begingroup$ K thanks. I will check it out. $\endgroup$ – A. E. Sam May 4 at 8:55
  • $\begingroup$ Every bit of evidence we have for anything whatsoever comes via our perceptions. $\endgroup$ – WillO May 4 at 14:35
  • $\begingroup$ @WillO You never saw the output of a radiotelescope, eh? $\endgroup$ – Carl Witthoft May 4 at 14:50
  • $\begingroup$ @CarlWitthoft: I do not get your point. Why does it matter whether I've seen the output or seen/heard someone else's account of the output? Either way I draw inferences only from what I've perceived. $\endgroup$ – WillO May 4 at 15:16
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So in that sense, what scientific evidence is there for the definable real world quality of redness independent our perception?

The atomic spectra evidence, they have specific frequencies for specific colors perceived by our eyes.

This is the electromagnetic spectrum as a function of the wavelength/frequency . Visible light is a very small part of the spectrum.

enter image description here

and this is the hydrogen , helium and neon emission lines in the red, with a unique frequency.

atomic spectra

The color our eyes see is double valued, it could be the unique frequency as above, but it also could be the perception of color by our eyes, where color is a many value combination of different frequencies.

enter image description here

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  • $\begingroup$ This is very useful for defining what wavelengths we ascribe to "red-like" color, but I don't think it has much to do with the philosophical jargonese about "redness" $\endgroup$ – Carl Witthoft May 4 at 14:51
  • $\begingroup$ @CarlWitthoft I am answering the summary question, this is a physics site , not a philosophy one, the sentence I quote is about and can be answered within mainstream physics $\endgroup$ – anna v May 4 at 15:14
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There is no evidence for "redness" in the sense of "perception or the sensation of red" outside humans (and some animals). There is plenty of evidence of photons with certain wavelengths that make us perceive red.

The argument between Goethe and Newton is basically about "colour is subjective experience" and "colour is a physical phenomenon". As Anna V's answer shows, we have a good grasp of what the physics of light is and even how light of different types produce subjective sensations of colour. Now, what those subjective colour sensations are is a deep unresolved philosophical matter - some of us in the philosophy department end up debating the nature of qualia endlessly. But the whole quarrel Goethe-Newton is about mixing up the two different meanings of colour.

It is a bit like the old chestnut "what if a tree falls in the forest and nobody is around to hear it, does it make a sound?" The answer is that because of energy conservation we can be pretty certain there are air and soil vibrations (sound as waves in a medium). But there is nobody there experiencing it (sound as hearing). Mixing up the meanings makes it seem more mysterious than it is.

A lot of physics is about taking everyday concepts (heat, brightness, motion) and refining them so we can meaningfully talk about the processes involved and predict what will happen in experiments. Usually that pushes out the perceptual and subjective experience from the description of the phenomenon itself and leaves it on the table of cognitive scientists to study. Goethe was not a fan of this kind of reductionism, but his Naturphilosophie does not seem to have produced many useful results (but perhaps a fair bit of useful critique).

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