When did East Asian countries adopt the Western calendar?
Douglas Pruitt, Warren, Vermont
It depends on the country. Japan began using the Gregorian calendar in 1873, Korea in 1896 and China in 1912, and they use it as the standard for official and international matters. But these countries still refer to their traditional lunisolar calendars, where dates are based on the positions of the sun and moon, for birthdays and cultural events, says James Ulak, senior curator of Japanese art at the Freer Gallery of Art and the Arthur M. Sackler Gallery. (Japan, notably, has a hybrid calendar that combines Gregorian elements with references to Emperor Akihito’s reign.) North Korea is on a totally different timeline: Its calendar starts with the birth of its founder, Kim Il-Sung, in 1912.
If a photon of light, once emitted, travels through the universe unobstructed, will it travel at the speed of light forever? If so, will it reach—or even surpass—the edge of the observable universe?
Brie Stolter, New York City
Yes and no, says Avi Loeb, a theorist at the Harvard-Smithsonian Center for Astrophysics. According to Einstein’s Theory of Relativity, the photon will travel at the speed of light forever. But where the photon ends up is complicated. The distance light has traveled in the time since the Big Bang determines the extent of our observable universe. We don’t actually know if there’s an edge of the universe, and we may never know: The universe is accelerating as it expands, so we’ll never see beyond what we can see now.
What prompted the rise of ledger art among the Plains Indians?
Chase Carter, Washington, D.C.
In a word, necessity. Traditionally, Plains warrior-artists had depicted feats of war, horse raids, courtship scenes and religious rites on animal hides. When hides became scarce in the 19th century after non-Natives hunted the buffalo to near-extinction, artists turned to canvas, muslin and, eventually, pages from ledger books. Ledger art flourished into the early 1900s, then languished for decades before undergoing a revival beginning in the 1970s. It is still thriving, says Emil Her Many Horses, curator of the National Museum of the American Indian’s 2016 exhibit “Unbound: Narrative Art of the Plains,” with a greater range of topics and materials and a number of women artists in what had been a male-dominated field.
The Centralia Mine Disaster of 1947 killed 111 miners. Did it have any impact on mine-safety laws?
Joseph Partain, Iuka, Illinois
The explosion in that Illinois mine, believed to be caused by the ignition of coal dust, devastated the community and inspired three Woody Guthrie songs (“The Dying Miner,” “Waiting at the Gate” and “Talking Centralia”). But it had limited legal impact, says Peter Liebhold, mining curator at the National Museum of American History. Congress passed a mine-safety law that year, but it had no enforcement provisions and expired after a year. After another Illinois coal-mine explosion killed 119 people in 1951, Congress passed the Federal Coal Mine Safety Act, mandating federal mine inspections.
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