Short answers, pulled from the story.
Black is defined as the color perceived when no visible light reaches the eye, resulting from the absence or complete absorption of all wavelengths of visible light. A black pigment absorbs almost all light rather than reflecting it. As of September 2019, the darkest material known was made by MIT engineers from vertically aligned carbon nanotubes, with a 99.995% absorption rate.
Black became a dominant fashion color in the 14th century, when high-quality black dyes first became available and wealthy northern Italian merchants adopted black robes after sumptuary laws restricted bright colors to the nobility. By the end of the 16th century, nearly every monarch in Europe wore black. Coco Chanel's simple black dress, published in Vogue in 1926, transformed women's fashion worldwide.
Judges began wearing black robes in Europe in the 13th and 14th centuries to signal the seriousness and authority of their positions. Jurists in France adopted black robes during the reign of Philip IV (1285-1314), and in England the custom began from the time of Edward I. The robes resembled clerical dress and represented the law of the king, just as priests' robes represented the authority of the church.
Olbers' paradox, first noted in 1823 by German astronomer Heinrich Wilhelm Matthias Olbers, asks why the night sky is dark if the universe is infinitely large and full of stars. The accepted answer is that the universe is about 13.8 billion years old, so light from distant stars has not yet reached Earth. Additionally, as the universe expands, stars move away and their light redshifts toward invisibility through the Doppler effect.
Anarchism, popular in the late 19th and early 20th centuries, used a black flag or black letter A as its symbol. Italian fascists adopted black uniforms inspired by the Arditi, Italy's elite World War I storm troops; Benito Mussolini came to power in 1922 with his black-shirted followers. The Nazis made black the color of the SS uniform, worn from 1932 until the end of World War II.
Paleolithic artists at Lascaux Cave in France used charcoal to paint animals between 18,000 and 17,000 years ago, later achieving darker pigments by burning bones or grinding manganese oxide. In Roman times, vine black was produced by burning grapevine branches. The 15th-century Florentine painter Cennino Cennini recorded recipes for lamp black, vine black, and a fine black made from burning almond shells or peach pits.