alek0

Volker,

what you mentioned is the dielectric constant of vacuum. What I mentioned is a relative dielectric function which is wavelength dependent and does not have any dimension or any unit. The same way as refractive index. So for example dielectric constant of quartz in visible range is not 8.854 187 817 x 10^-12 F m^-1, it is rather 2.1025 * 8.854 187 817 x 10^-12 F m^-1, where 2.1025 is the relative dielectric function, which does not have a unit. It is in general frequency dependent, though varies very slow over the visible range.

If you have actually looked at CIE definitions of CIE coordinates, you would have seen that they are determined by integrating spectral distribution of the source S (which can be spectral radiant flux, irradiance or radiance, each of which has a unit, for radiance spectral distribution it is W/sr m^2 nm) multiplied by three response curves over a visible spectral range. Then when you obtain all three integrals X, Y, Z (one for each of the three color matching functions). Then you get chromaticity coordinates as:
x=X/(X+Y+Z) and y=Y/(X+Y+Z)

There is no unit because it is a ration. X, Y, Z have a unit because S has a unit (but unit will be different, i.e. no division with nm because of integration over wavelength).

In the same way that absorption does not have a unit, it is just a number because it is a ratio of two qunatities with same units. The color is determined based on the spectral distribution. It has real physical nature because spectral distribution has real physical nature. How we express it (i.e. color matching functions defined according to typical response of human eye) is a matter of convention. But on the other hand, SI units are a matter of convention as well.

Volker,
if you claim that color is not physical part of nature since it does not have a SI unit, please tell me is refractive index part of nature? It does not have a unit either.

Volker.Doormann

If you agree, then you agree with the independence of color and some wavelengths of electromagnetic intensities in the 500nm range.

While it is no doubt, that electromagnetism is physical, it would be helpful to proof further claims regarding color to be as a of physical nature.

I think there is a total agreement, that all physical processes in the body or in the brain inclusive the processes in the mind in total are pure physical. The mind and his memory, all physically connections between neurons are physical. No doubt.

But all this physical processes can not be shown or proved for the nonphysical. One can argue, that there are nothing beyond the physical, but already simple use of boolean algebra is an acknowledgement of a nonphysical existence, because boolean algebra has no provable physical properties.

In my posting, from this split about color is threaded, I have distinguish between the physical and the nonphysical. It seems, that there is a broad knowledge about the physical, but not about the nonphysical in this world.

No one can explain, why there is a color impression in the consciousness, but nevertheless a lot of voices claim color as physical, without any scientific proofs as a known physical process.

I think it is not realy necessary to acknowledge the nonphysical, like logic, math, or ethic, but if one claims the nonphysical as physical, then he must show by proof, that his claim is of any relevance.

I have not read any arguments, that color could be proved as of physical nature, acknowledged by all physicist of the science of nature.

Volker

Volker.Doormann

A refractive index is a technical factor describing the ratio of the vacuum velocity of light to the light velocity in a dielectric material. The velocity of vacuum is measured in m s^-1.
This are two SI units.

BTW. The relation of the wavelength depending optical dielectric tensor and the refractive index I have noted in a published paper in J. Appl. Phys. 68(7), 1990, 3544 doormann.org/pap01.jpg .

To deal with ratios without respecting their absolute dimensions, and take this as argument, that it should be prove, that factors should have a physical existence, is of no scientific practice.

I think it is of no value to lecture the whole physic across here. Colors as white, brown, pink or magenta must be expressed by SI units if one claims that color has a physical dimension.

Volker

Feather

You are speaking gibberish, Volker. On one hand you assert that "color" is some objective thing, but only in the "spiritual" realm, and on the other you pose the question "does 'color' have physical dimension." You've already answered your question and refuse to hear any other arguments.

At this point I will conclude that you are trolling and quit.

Volker.Doormann

I have learned that it is senseless to discuss assertions of persons. I think it is only of interest, weather a saying is true or not, independent of the speaker. I think it is very easy to recognize the truth, that color has no physical base. If one knows, that color is a physical phenomena, there are a lot of freedom to argue on this in a scientific manner.

Yes, I thinks there are a lot of existing spiritual dimensions, loaded with intelligence, logic, truth, love, ethic and order, which are of no physical existence. If one think, that color has no spiritual existence, then he can do experiments painting all his rooms black or dark gray illuminated by bright red light for some years.



I think it depends on the quality of the argument. As I have written here I do not think, that truth could be found in persons. Science doesn't stop beyond the physical. The nonphysical nature must respected in the same way as the physical nature as it is . The truth of the science of nature is not to be found by Assertions of persons. Assertions have no meaning while studying and recognizing the truth of the spiritual part of nature as it is .

Volker

Mageth

No one can explain, why there is a color impression in the consciousness, but nevertheless a lot of voices claim color as physical, without any scientific proofs as a known physical process.

Well, I can make a simplistic, educated guess as to why there is color sensation in the consciousness from an evolutionary standpoint. I'm not posing this as a thorough explanation for why we see color, BTW, because it's perhaps not satisfactory as a full explanation.

Simply put: color sensation is useful for us (and other species) in distinguishing among objects in our environment; i.e. it's superior to pure grayscale vision in telling things apart (if you're red-green colorblind, you know this by experience). As an example, it's easier to distinguish ripe fruit from unripe fruit using color vision than using grayscale vision.

As to the "known physical process" part, let me draw a parallel. Our vision also allows us to estimate dimension and distance, among other (obviously) physical aspects of our environment (e.g. velocity), and even to see three-dimensionally. As examples, using vision, most people can easily estimate distances and size fairly accurately, and can even deduce relative distance and relative size. And these physical aspects are estimated from what? From the "input" of photons striking our retinas, and the processing of the input in our physical brain. I would assume these physical aspects have SI units (though there was a time when they did not formally have SI units assigned to them). But I would note that our brains do the sensing and processing of such physical aspects quite well without using SI units; you might say we associate units with the measurements during "post-processing" of the sensual information.

Similarly, our vision has evolved to "estimate" and distinguish among color (i.e. varying wavelenghts or combinations of wavelengths of light). The varying colors we sense are the "units", so to speak, that are assigned by our brain and that allow us to distinguish among the varying wavelengths of light (like SI units for dimension, distance, and velocity, our brains can do all this without any actual knowledge of the EM spectrum, the wavelengths of light, SI units, etc.)

You're right; there's a bit of mystery about "why" we see yellow, red, brown, etc. But the mystery is not quite what you make of it, in my opinion, and is not that different from "why" we see three-dimensionally or perceive distance and size.

Reiterating, in my opinion, and admiteddly this is simplistic and may be unsatisfactory as a "full" explanation, we see various colors because that is the way we've evolved to distinguish detected regions of the visible spectrum of light, a useful survival trait for distinguishing among objects.

Mageth

I think it is very easy to recognize the truth, that color has no physical base. If one knows, that color is a physical phenomena, there are a lot of freedom to argue on this in a scientific manner.

Yes, I thinks there are a lot of existing spiritual dimensions, loaded with intelligence, logic, truth, love, ethic and order, which are of no physical existence. If one think, that color has no spiritual existence, then he can do experiments painting all his rooms black or dark gray illuminated by bright red light for some years.

Interestingly, you seem, in your arguments, to be objectifying color sensation, as if the "colors" we sense are something apart from what our minds generate.

Well, isn't that more or less what the "other side" is arguing? Are there SI units for spirit?

You'r argument seems to boil down to "if color cannot be proven physical, then it must be spiritual". Isn't that a bit of a fallacious argument? Especially when the existence of the spiritual is just as if not more lacking in evidence than the physicality of color?

I might argue that the brain could have evolved to assign different "units" to different wavelengths (perhaps even colors we don't perceive??? let's not go there) and you would not know the difference. There's no justification for assigning anything "special" to any particular color.

About your little experiment, it's known that different colors evoke different moods/emotions. No real need for assigning spiritual significance to that. Emotions are chemically-driven responses.

Mageth

This, somehow seems appropriate here:

Cold hearted orb that rules the night,
Removes the colours from our sight.
Red is grey and yellow white,
But we decide which is right.
And which is an illusion???

- From Late Lament , by Graeme Edge (off the Moody Blues' [i]Days of Future Passed[i]).

Valmorian

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Color DOES have a physical basis. Which physical basis you are referring to depends upon what you mean by color. If you mean the wavelength of light that corresponds to the experience of 'red', then you have that as a physical basis. If you are referring to the actual experience of 'seeing red', then you are referring to the quite physical stimulation of neurons in your brain that cause you to 'see red'.

The book "The Man Who Mistook His Wife For A Hat" by Oliver Sacks




I'm not sure why you would assume this is true. Is there a "Tennis" dimension that holds the game Tennis?





Not really sure what you are referring to here.

You are asserting that color is spiritual in nature.

Mageth

The book "The Man Who Mistook His Wife For A Hat" by Oliver Sacks

This seems to be a bit of an incompleted thought.

Nevertheless, thanks. I was trying to remember Sacks' name. This and one or two other books by Sacks are highly recommended reading for glimpses into human consciousness and its tight coupling to the physical brain and senses.