Where does color collide?

In the theory of the strong force, color is a three-valued quantum property carried by quarks and gluons, and it is the charge that binds them into protons, neutrons, and other particles. Fritzsch, Gell-Mann, and Leutwyler's 1973 Advantages of the color octet gluon picture set out this picture, in which the three values are conventionally labeled red, green, and blue. Those labels are pure bookkeeping and have nothing to do with any visible hue, and because of confinement no isolated colored particle can ever be observed. The referent is an abstract charge inside matter, not a hue you can see, a physical light stimulus, or a legal show of right.[1]

Unit

A three-valued quantum charge on a quark or gluon, not a perceived hue

Recovery means

Not applicable

Measured by

Inferred from particle physics data, such as the ratio of hadron to muon production, which counts the three color states

Here color is a perceptual attribute that the visual system builds from the signals of the eye's cone cells, not a property that light itself carries. Gegenfurtner and Kiper's 2003 review Color vision describes how the brain constructs color, so that two lights with quite different physical make-ups can look identical (metamerism) and one object can keep looking the same color as the light on it changes (color constancy). The referent is an experience in the mind produced by neural processing, distinct from the physical stimulus that triggers it, from a quark's charge, and from a legal appearance.[2]

Unit

A color experience, such as a named hue with a lightness and a vividness, produced by the visual system

Recovery means

Not applicable

Measured by

Studied by psychophysics, such as color matching and naming, and by recording neural responses in the retina and visual cortex

In the physics of light, color is a property of the light stimulus itself, fixed by how much energy it carries at each wavelength and reduced to a small set of numbers so that lights can be matched and reproduced. Smith and Guild's 1931 The C.I.E. colorimetric standards and their use set out the standard by which any light is given three coordinates in a shared color space. The referent is a measured physical stimulus and its coordinates, standing between the raw wavelengths of light and the color a viewer sees, and it is neither the perception in the mind, the quark's charge, nor the legal appearance.[3]

Unit

A light stimulus reduced to tristimulus coordinates, such as the CIE X, Y, and Z values

Recovery means

Not applicable

Measured by

Measured with a spectrophotometer or colorimeter and computed against the CIE standard observer functions

In legal usage, color means the mere appearance or semblance of a right or authority, as opposed to the real thing. As set out in Black's Law Dictionary, a colorable claim looks valid on its face, color of title is an apparent but defective ownership, and acting under color of law is acting with the outward show of official authority. The referent is a pretext or surface appearance judged against an underlying reality, and it shares only its spelling, and a Latin root meaning outward appearance, with the physical, perceptual, and particle-physics meanings of the word.[5][4]

Unit

A claim, title, or authority that has the outward appearance of legality

Recovery means

Not applicable

Measured by

Assessed by courts, which judge whether an apparent right or authority is genuine or only colorable