I really do not understand why you would think that the colors would scintillate.

Image a single point source of pure red light coming to our eyes from an otherwise completely black vista. (Think:a laser sight aimed at us in a dark room.) As we move our eyes, (or they twitch with our pulse), the photons from that (for arguments sake impossibly fine), point source would alternately fall on "red" cones, "green" cones and "blue" cones.

As we move our eyeballs, the image in our brains doesn't move. The brain maps the tristimulus values originating from different (and widely spaced) cones, back to the same point within our mental image. Without persistence of vision, our perception of the colour of that single point in our mental image, would change as the photons originating from it stimulated different cones with their differing spectral responses. But that doesn't happen.

With persistence of vision, the colour we perceive coming from that point source is an averaged combination of the responses generated by the photons falling on lots of different (and different 'coloured') cones over time as our eyes move. In this artificially simple case, the colour we perceive in our brain at the point source, is an amalgam of the tristimulus responses from all the cones that those pure "red" photons hit as our eyes move, and we attach the label "red" to that amalgam.

In the real world there are no pure frequency point sources. The photons reaching our eyes from any given point (or rather, from the same directional vector), will be a mixture of many frequencies. In the case of a rainbow, given the distance between our eye and the raindrops that are responsible for the rainbow, we will be unable to resolve anything less than (say) a square foot, or a square metre, or maybe larger in the XY planes. And indeed, we mustn't forget that the raindrops that form the appropriate angle between our eyes and the Sun will not all be exactly in the same plane in the Z axis. And the raindrops themselves are falling at some rate.

So the light reaching our eye and being resolved to a single point in our mental image within any given period of persistence, will have come from some or all of the raindrops that passed through a cube (or sphere) of air 10s or 100s of miles away. And there will be some light being reflected from the outsides of raindrops both further away and closer to us that will arrive at our eyes coincident with the refracted light. And some of the spectral components refracted will have been attenuated by the air and water molecules between the refracting raindrop and our eye.

The colour we perceive will be the result of the amalgamation of all those stimulations within the period of persistence.

The important point is that I really don't understand why you think we should anywhere perceive pink in the rainbow. Particularly since I don't see it when I look at the rainbow.

Well, the first question to ask, is when was the last time you actually looked at a real rainbow with your own eyes?

As opposed to a instantaneous frozen image of one interpolated through a CCD device with some number of bits of A/D conversion, thence further manipulated (reduced) into a jpg, png or (if you are lucky) tiff format file, and probably resized with the additional quantizing that entails.

And even when you have viewed a real rainbow in real time, if one (or a dozen, or a hundred thousand) raindrops within the auspices of those nominally refracting the blue end of the spectrum, happened to have dissolved in it some contaminant that caused it to refract or reflect only the red components of the spectrum, do you think that given the persistence of your vision, you would detect the resultant, brief pink hue?

Even via the analogue processes of film or slide production, and with the fastest shutter speed possible, the energies of many millions of photons will have contributed to, and been averaged to produce the hue displayed for any given point in the picture.

All the scientific models are based around infinitesimal points and pure frequency sources, but it is naive to believe that this could ever occur outside of laboratory conditions. That's why NASA go to such great lengths to try and adjust the raw data produced by their cameras on Mars, or Cassini, to produce "naturalistic" color photos. So that we might get something of an impression looking at those photos of what we would actually see were we standing where their cameras are mounted.

The colours we perceive, and the labels we attach to them, are entirely constructed within our brains. And for any hue we perceive, there are almost infinite number of mixes of frequencies of photons that will reach our eyes in a given period of time, from a given vector, that will result in us perceiving that hue.

I'm sorry, but you aren't exactly making a lot of sense. While theoretically there are a lot of things that could happen for split seconds, depending on which receptors get hit, etc, the odds against them happening are incredibly high. And the odds against them continuing to happen long enough to get noticed are so high that that is effectively impossible.

To a very high degree of precision, a rainbow will cause specific pure frequencies to arrive at specific angles, with a calculable correlation between the angle and the spectrum that arrives. To a reasonable degree of precision, you will perceive a specific frequency of light as a specific colour. Most people will have the similar responses to specific frequencies of light. And there is simply no pure frequency of light that is perceived as pink.

This is pretty basic, and should be pretty simple. I have verified this in the past while looking at real rainbows, pictures of rainbows, and the output of prisms. Philosophical musings on the caprices of point sources, chance photons, and pure frequencies don't change it. Neither do howlers about why the output from cameras on various space missions needs massaging to produce natural looking photographs. (Giant hint, the various cameras used on space missions generally have frequency responses that aren't close to any of the major receptors in our eyes.)

As far as I am concerned this thread is over. Respond if you like, but I see no point in repeating myself.

Since you won't take my word for it, and seem incapable of seeing that your schoolboy physics doesn't apply in the real world, trying reading the research by Raymond L. Lee, Jr. in his 1991 paper: “What are ‘all the colors of the rainbow’?”.

I'll quote one paragraph from the intro that supports everything I've been saying above:

Some 50 years ago, Humphreys pointedly noted that "the 'explanations' generally given of the rainbow [in textbooks] may well be said to explain beautifully that which does not occur, and to leave unexplained that which does.'

Many nontextbook factors that affect the color and luminance of the natural rainbow still go largely unconsidered.

These factors include:

1. the angular divergence and coherence of sunlight,
2. the optical path length of rain showers,
3. the spectrum of raindrop sizes,
4. aerosol scattering and absorption,
5. aerodynamic distortion of raindrops, and
6. illumination of the rainbow's background

To do full justice to the natural rainbow, we must do much more than uncritically apply a rainbow theory to monodisperse, spherical raindrops that are illuminated by perfectly collimated light and seen against a black background.

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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

To a very high degree of precision, a rainbow will cause specific pure frequencies to arrive at specific angles,

You surprise me Tilly. Cos that is utter bollocks.

Get the equipment: PMOSFET image sensor; an optical collimator lens system; an optical refraction grid; and a spectrum analyser. Source your light from natural sources, and apply an H2O mist between the refraction grid and the detectors. Do the experients. Measure the frequencies. Then come back and claim that you know what you are talking about.

And there is simply no pure frequency of light that is perceived as pink.

True. But under natural lighting conditions, within any human measurable period, no pure frequencies of light reach the human eye. They are always a mixture of refracted, reflected and incident light from many origins and filtered through whatever molecules exist on their paths from source to eye.

Update:Have you never seen pinks and purples in a sunset?

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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."