a group of stars.
Asterism “a group of stars” derives from Ancient Greek asterismós “a marking with stars,” from astḗr “star.” Astḗr comes from the Proto-Indo-European root ster-, of the same meaning, which is also the source of English star and Latin stella. For the latter, compare constellation “any of various groups of stars to which definite names have been given,” which is often conflated with asterism, but the two share a slight distinction. An asterism is a group of stars, while a constellation is the named shape that multiple asterisms form. For example, the Big Dipper is an asterism comprising seven stars, but Ursa Major is the constellation that contains the Big Dipper as well as several other asterisms. Asterism was first recorded in English in the 1590s.
In a sky so full of stars it’s often difficult to figure out where constellations are, one dark spot stands out: The Coalsack Nebula. Parked near one of the five brightest stars comprising the Southern Cross—perhaps the most easily spotted asterism in the southern sky—the nebula looks like an inky black thumbprint. Where it hangs, the stars struggle to shine. It’s as if someone outlined a portion of the sky and dimmed the lights.
Examples of confusing and misleading scientific terms abound. When astronomers say “metals,” they mean any element heavier than helium, which includes oxygen and nitrogen, a usage that is massively confusing not just to laypeople but also to chemists. The Big Dipper isn’t a constellation to them; it is an “asterism.”
Persnickety “overparticular, fussy” is a variant of pernickety, a Scottish English word of uncertain origin. Per- is a common prefix in expressive words in the Scots language, such as perjink “exact, neat, trim,” perskeet “fastidious,” and perjinkity “exact detail,” all of which are similar in meaning to persnickety. One hypothesis is that persnickety and pernickety are compounds of this prefix per- and the noun nick “small notch, hollow place” or a diminutive of nick such as nickett. Alternatively, persnickety could be related to the adjective snickety, also meaning “fussy,” or to the noun snicket “passageway between walls or fences,” but the connection is unclear. The final theory is that persnickety and pernickety are heavily corrupted variants or fusions of particular “exceptionally selective” and finicky “excessively fastidious.” Persnickety was first recorded in English in the late 1880s.
Many of the women (and a few men) were tourist attractions in their own right, with visitors flocking to the hotel as much to glimpse a quirky widow as to see the Pulitzer Fountain or to have a drink in the Oak Room. The Plaza staff grew accustomed to the widows’ peculiarities. One hotel manager began walking outside to get from one end of the building to the other, to avoid passing through the lobby, where persnickety widows would invariably be positioned on the divans, ready to greet him with a barrage of complaints.
the generalization of a cube to four dimensions.
Tesseract “a four-dimensional cube” derives from Ancient Greek tésseres (also téttares) “four,” which is also the source of tessellate “to form small squares,” after the number of sides in a square, and the combining form tetra- “four,” as in tetrahedron, a figure with four faces, and tetralogy, a series of four related books or films. Tésseres comes from the Proto-Indo-European root kwetwer-, which is the source of English four, forty, fortnight, and farthing and Latin quattuor and quadri- “four” (as in quatrain, a four-line poem, and quad, a four-sided common space), quārtus “fourth” (as in quarter, which is one-fourth of a dollar), and quater “four times” (as in quaternary “consisting of four”). Tesseract was first recorded in English in the late 1880s.
The robot is building a tesseract. He motions at a glowing cube floating before him, and an identical cube emerges. He drags it to the left, but the two cubes stay connected, strung together by glowing lines radiating from their corners. The robot lowers its hands, and the cubes coalesce into a single shape—with 24 square faces, 16 vertices, and eight connected cubes existing in four dimensions. A tesseract. This isn’t a video game. It’s a classroom. And the robot is Brian Greene, a physicist at Columbia University and bestselling author of several popular science books.
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