Science Fair Project Encyclopedia
White is a color (more accurately it contains all the colors of the spectrum and is sometimes described as an achromatic color—black is the absence of color) that has high brightness but zero hue. The impression of white light can be created by mixing (via a process called "additive mixing") appropriate intensities of the primary color spectrum: red, green and blue, but it must be noted that the illumination provided by this technique has significant differences from that produced by incandescence (see below).
In painting, white can be created by reflecting ambient light from a white pigment. White when mixed with black produces gray. To art students, the use of white can present particular problems, and there is at least one training course specialising in the use of white in art.
Until Newton's work became accepted, most scientists believed that white was the fundamental color of light; and that other colors were formed only by adding something to light. Newton demonstrated that white was formed by combining the other colors.
In the science of lighting, there is a continuum of colors of light that can be called "white". One set of colors that deserve this description are the colors emitted, via the process called incandescence, by a black body at various relatively-high temperatures. For example, the color of a black body at a temperature of 2848 kelvins matches that produced by domestic incandescent light bulbs. It is said that "the color temperature of such a light bulb is 2848 K". The white light used in theatre illumination has a color temperature of about 3200 K. Daylight has a nominal color temperature of 5400 K (called equal energy white), but can vary from a cool red up to a bluish 25,000 K. Not all black body radiation can be considered white light: the background radiation of the universe, to name an extreme example, is only a few kelvins and is quite invisible.
Standard whites are often defined with reference to the International Commission on Illumination's (CIE's) chromaticity diagram. These are the D series of standard illuminants. Illuminant D65, originally corresponding to a color temperature of 6,500 K, is taken to represent standard daylight.
Computer displays often have a color temperature control, allowing the user to select the color temperature (usually from a small set of fixed values) of the light emitted when the computer produces the electrical signal corresponding to "white". The RGB coordinates of white are 255 255 255.
Usage, symbolism, colloquial expressions
- The term white is often used in the West to denote "race" for so-called Caucasian people, i.e. people of European/West Asian descent with light skin color, whose skin color actually ranges from pink to pale brown, and overlaps with some people that might be classified as "Blacks". For more details, see Whites.
- White noise, in acoustics, is a sibilant sound that is often a nuisance, although it can also be deliberately created for test purposes.
- Whitewash, figuratively, means an attempt to obscure the truth by issuing a blanket of lies. See propaganda.
- Whiteout is a weather condition in which visibility is reduced and surface definition lost in snowy environments.
- White is often associated with Conservatism (as opposed to Communism), particularly in the years following World War I, with civil wars fought between "Reds" and "Whites", for instance the Civil War in Russia and the Civil War in Finland.
- A white flag is an international sign of either surrender, or truce, that is, it is a sign of peaceful intent, typically at time of war.
- The white ribbon is worn by movements denouncing violence against women. It is also worn by some feminists and was a symbol for peace in Quebec, in the beginning of 2003, as part of the popular opposition to war on Iraq.
- To "show the white feather" is to display cowardice. In cockfighting, a white feather in the tail is considered a mark of inferior breeding. In Victorian England a purported coward would be presented with a white feather.
- White is also one of the two opponents in many board games of abstract strategy, such as go, chess, and checkers.
White in heraldry
Arthur Charles Fox-Davies has argued that white can be considered a tincture in heraldry separate from its use to represent argent, and in fact the labels borne on the arms, crests and supporters of members of the British Royal Family other than the reigning sovereign are invariably shown as white.
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details