Things to think about in your free time.

Music by Suspenseful Cinematic Sting View more by SUBMORITY from pixabay and Cool Revenge Jeremy Blake. Editor's Note: This article originally appeared in the October 2005 issue of Scientific American. In May 1972 a worker at a nuclear fuel–processing plant in France noticed something suspicious. He had been conducting a routine analysis of uranium derived from a seemingly ordinary source of ore. As is the case with all natural uranium, the material under study contained three isotopes— that is to say, three forms with differing atomic masses: uranium 238, the most abundant variety; uranium 234, the rarest; and uranium 235, the isotope that is coveted because it can sustain a nuclear chain reaction. Elsewhere in the earth’s crust, on the moon and even in meteorites, uranium 235 atoms make up 0.720 percent of the total. But in these samples, which came from the Oklo deposit in Gabon (a former French colony in west equatorial Africa), uranium 235 constituted just 0.717 percent. That tiny discrepancy was enough to alert French scientists that something strange had happened. Further analyses showed that ore from at least one part of the mine was far short on uranium 235: some 200 kilograms appeared to be missing— enough to make half a dozen or so nuclear bombs. A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are diverging or converging, and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge, such as the Mid-Atlantic Ridge, has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary, 3,000 kilometers deep within Earth.

Dolichotis is a genus of the cavy family of rodents.[1] These large relatives of guinea pigs are common in the Patagonian steppes of Argentina, but also live in Paraguay and elsewhere in South America. It contains a single extant species, the Patagonian mara, which is one of the largest rodents in the world after the two species each of capybaras and beavers, and the large species of porcupines, reaching about 45 cm (18 in) in height. The Chacoan mara has and sometimes still is also considered a member of this genus. However, a 2020 study by the American Society of Mammalogists found significant difference between the two mara species to warrant placing it in the genus Pediolagus.[2]

*Moses masc. proper name, name of the Hebrew prophet and lawgiver, Middle English Moises, from Latin, from Greek Mouses, from Hebrew MOS-heh, which is of unknown origin. *Aaron masc. proper name, in the Old Testament the brother of Moses, from Hebrew Aharon, which is said to be probably of Egyptian origin. The Arabic form is Harun. Related: Aaronic. Aaron's beard as a popular name for various plants (including St. John's wort and a kind of dwarf evergreen) deemed to look hairy in some way is from 1540s. Aaron's rod is from 1834 in botany, 1849 in ornamentation; the reference is biblical (Exodus vii.19, etc.). *Miriam fem. proper name, biblical sister of Moses and Aaron (Exodus xv.20), from Hebrew Miryam (see Mary). *Mary fem. proper name, Old English Maria, Marie, name of the mother of Jesus, from Latin Maria, from Greek Mariam, Maria, from Aramaic Maryam, from Hebrew Miryam, name of the sister of Moses (Exodus xv), a word of unknown origin, said to mean literally "rebellion." The nursery rhyme "Mary had a Little Lamb" was written early 1830 by Sarah Josepha Hale of Boston and published September 1830 in "Juvenile Miscellany," a popular magazine for children. Mary Jane is 1921 as the proprietary name of a kind of low-heeled shoe worn chiefly by young girls, 1928 as slang for marijuana. Mary Sue as a type of fictional character is attested by 1999, from the name of a character in the 1973 parody story A Trekkie's Tale.

ark (n.) Middle English arke, from Old English earc, Old Northumbrian arc, mainly meaning Noah's, but also the Ark of the Covenant (the coffer holding the tables of the law in the sanctum sanctorum), from Latin arca "large box, chest" (see arcane), the word used in the Vulgate. arcane (adj.) "hidden, secret," 1540s, from Latin arcanus "secret, hidden, private, concealed," from arcere "to close up, enclose, contain," from arca "chest, box, place for safe-keeping," from PIE root *ark- "to hold, contain, guard" (source also of Greek arkos "defense," arkein "to ward off;" Armenian argel "obstacle;" Lithuanian raktas "key," rakinti "to shut, lock").

Peter masc. proper name, 12c., from Old English Petrus (genitive Pet(e)res, dative Pet(e)re), from Latin Petrus, from Greek Petros, literally "stone, rock" (see petrous) petrous (adj.) c. 1400, in anatomy, "very hard, dense,"

Jesus walking on water is a metaphor for oil floating on water.