The Newtonian reality vs The Goethean fantasy in colour theory. If you can handle truth, here you'll find the evidence.

When it comes to colour theory there is no doubt in my mind that today there are many more followers of Goethe's vision on the subject than Newton's. Every single day I receive in my inbox dozens and dozens of notifications about new papers, articles, videos and books purporting in no uncertain terms that Goethe's theory of colours is, at the very least, as true and valid scientifically as Newton's own. But the simple reality is that those claims are simply, plainly, clearly and thoroughly demonstrably, absolutely false. And in this post I'll show you that what I've just said is true. Let's go.

One of those many followers of Goethe's vision of colour is the physicist Pehr Salstrom. Salstrom is the author of a great number of papers, articles, videos, websites and lectures whose only topic of discussion is Goethe's great insights into the colour phenomena as opposed to Newton's quite superficial and murky views on the subject. Unfortunately for Salstrom the real truth is that his own vision on the subject is so debilitatingly myopic that he can barely see a tree at a time, never mind a forest. For instance, on the page called Goethe, Newton and the physics of colour of his website he writes:

In "Beiträge zur Optik" Goethe advises us to look through a glass prism and observe the colour phenomena that appear. It soon becomes evident to the observer that colours appear at distinct borders between dark and bright areas in the field of view. If you vary the geometrical conditions you find that all of the various configurations can be boiled down to four principal spectra: The two border-spectra and and the two aperture-spectra and .

Then he shows the image below, supposedly as a confirmation of the paragraph above.

The painful truth however (for Salstrom and the like, of course) is that everything above is so easily shown to be blatantly unsatisfactory that, for all intents and purposes, their scientific value is exactly nought, zilch, zero, nothing, bugger all. Let me show you why.

Take first the picture above and read carefully the explanation given. What do you think about that? Whatever you may think the truth is that both what is shown and what's said is basically a genuine example of pure crap. Firstly, because of these statements:

The black-and-white picture to the left is viewed through a glass prism. It then looks as shown to the right.

That's not necessarily true. Not at all. To see that what I said is true grab a triangular prism, hold it with its apex pointing to your left and look at the left figure above. Does it look at all with what is shown in the picture on the right? Absolutely not. For instance, from a distance of about 80 cm, and with the prism oriented as I mentioned what you will see is what's shown below on the right.

(Now, let me say this: I dare you, Pehr Salstrom, or anyone else in this world, to come forward and explain what is shown above on the right by using Goethe's theory of colours. Come on, people, I will be waiting eagerly for your Goethean reply.)

It's clearly obvious that Salstrom--and everybody else, beside my humble self--has no idea what exactly determines the colours that will invariably be seen in all subjective observations. To my mind it's an absolutely flabbergasting fact that for three and a half centuries not one of our highly educated physicists has managed to resolve even such an embarrassingly simple matter. 

And there then is this other moronic declaration in Salstrom's cited paragraph above:

If you vary the geometrical conditions you find that all of the various configurations can be boiled down to four principal spectra: The two border-spectra  and  and the two aperture-spectra  and .

What is this guy saying!? That there are four principal (whatever that means) spectra and that the RGB and CMY are aperture-spectra (whatever that's supposed to mean)!!??

In stark contrast to Salstrom's declaration I will tell you a much, much simpler little piece of truth. Which is that I can thoroughly account (meaning qualitatively and quantitatively too) for all conceivable subjective observations by using one, and only one, spectrum: The Newtonian RGB trio

Let us begin with a new, and hitherto unknown, fact. Which is that in subjective prismatic observations the primary colours do not refract at all if they are cast against a white background. Let me now provide you with a valid demonstration of that statement. (See the diagram below.)

To prove that what I said is true we will observe the diagram above through a triangular prism (held with the apex pointing to the left) from a distance of about 70-80 cm. Following that I will then account (both qualitatively and quantitatively, as I promised) for every colour that will be seen by the observer. Finally, as we'll proceed ahead, I will also explain the reasons for those black and magenta rectangles.

So, let us begin our prismatic observation now.

Next, I will drop another diagram below, which will basically depict all colours that you have observed through your prism a few moments ago.

I shall begin by first accounting for those colours on display between rectangle number 1 and 2, respectively. On the right there is a quite broad Y band and a much narrower R one, while on the left we have a broad B band and a narrow C one. The first important thing to note is that the width of the Y is equal to the width of the B. Similarly, the widths of the C and R are also the same. Both sets of colours, which physicists call (unjustifiably) the boundary spectra, are generated by the white area between the black rectangles when it is looked at through a prism. For those who don't know, the original width of that white area is now identical numerically to the sum of the current widths of the white part, the C band and the Y one. Therefore, we also know with absolute certainty that the B and the R bands have been deflected by our prism in opposite directions and are currently occupying areas that formerly were part of the two black (1 and 2) rectangles. So, once again, C and Y are sitting on white, and B and R are sitting on black.

And now we're ready to explain (qualitatively and quantitatively) how the colours in question have come into existence, after all. It's all so simple and straightforward that I should really add nothing to the above. But... 

The area that to the naked eye appeared white (see the first, un-prismatic picture) was really the effect of a B, G and R superposition of three different wavelengths of light. Observing that white area through a prism, however, is visually altered in the following manner. The B part of the white rectangle is dramatically moved in the direction of the apex of the prism; the R part, on the other hand, is moved--significantly less--in the direction where the base of the prism is pointing. These two prismatic deflections change--in a direct and proportionate manner--the formerly perfectly symmetric superposition of lights. Thus, as a direct and proportional effect, the movement of the B towards the left has left an area equal in size where there are now only two superimposed upon each other colours, those of R and G, of course. The area in question is therefore Y, and it is exactly of the same size with that of the B area of displacement. Conversely, the displacement of the R towards the right has left an area equal in size to its own, where only two of the primary colours are still superimposed upon each other. And those two specific colours are, naturally, the B and G ones. Hence the C band on the left.