Have a deep view into what people are curious about.

A shaft passer is a hypothetical device that allows a spoked wheel to rotate despite having a shaft (such as the axle of another wheel) passing between its spokes. The device is usually mentioned as a joke between nerds, in the manner of a fool's errand, since there is no evidence of one ever having been constructed until very recently.

One of the earliest printed references to these devices was made by Richard Feynman, who was told by a colleague at Frankford Arsenal in Philadelphia that the cable-passing version of the device had been used during both world wars on German naval mine mooring cables, to prevent the mines from being caught by British cables swept along the sea bottom.

The device was supposed to work using a spoked, rimless wheel that allows cables to pass through as it rotates. The ends of the spokes are widened, and the cable is held together by a short curved sleeve through which these spoke ends slide.

🔗 United States 🔗 Biography 🔗 Women's History 🔗 Christianity 🔗 Gender Studies 🔗 United States/Rhode Island 🔗 Christianity/Religious Society of Friends (Quakers)

The Public Universal Friend (born Jemima Wilkinson; November 29, 1752 – July 1, 1819) was an American preacher born in Cumberland, Rhode Island, to Quaker parents. After suffering a severe illness in 1776, the Friend claimed to have died and been reanimated as a genderless evangelist named the Public Universal Friend, and afterward shunned both birth name and gendered pronouns. In androgynous clothes, the Friend preached throughout the northeastern United States, attracting many followers who became the Society of Universal Friends.

The Public Universal Friend's theology was broadly similar to that of most Quakers. The Friend stressed free will, opposed slavery, and supported sexual abstinence. The most committed members of the Society of Universal Friends were a group of unmarried women who took leading roles in their households and community. In the 1790s, members of the Society acquired land in Western New York where they formed the township of Jerusalem near Penn Yan, New York. The Society of Universal Friends ceased to exist by the 1860s. Many writers have portrayed the Friend as a woman, and either a manipulative fraudster, or a pioneer for women's rights; others have viewed the preacher as transgender or non-binary and a figure in trans history.

🔗 Metalworking 🔗 Measurement

A thousandth of an inch is a derived unit of length in a system of units using inches. Equal to 1⁄1000 of an inch, a thousandth is commonly called a thou (used for both singular and plural) or particularly in North America a mil (plural mils).

The words are shortened forms of the English and Latin words for "thousand" (mille in Latin). In international engineering contexts, confusion can arise because mil is a formal unit name in North America but mil or mill is also a common colloquial clipped form of millimetre. The units are considerably different: a millimetre is approximately 39 mils.

🔗 Correction and Detention Facilities

This is a list of countries by incarceration rate.

🔗 Telecommunications 🔗 Meteorology 🔗 Astronomy 🔗 Solar System

The solar storm of 1859 (also known as the Carrington Event) was a powerful geomagnetic storm during solar cycle 10 (1855–1867). A solar coronal mass ejection (CME) hit Earth's magnetosphere and induced the largest geomagnetic storm on record, September 1–2, 1859. The associated "white light flare" in the solar photosphere was observed and recorded by British astronomers Richard C. Carrington (1826–1875) and Richard Hodgson (1804–1872). The storm caused strong auroral displays and wrought havoc with telegraph systems. The now-standard unique IAU identifier for this flare is SOL1859-09-01.

A solar storm of this magnitude occurring today would cause widespread electrical disruptions, blackouts and damage due to extended outages of the electrical grid. The solar storm of 2012 was of similar magnitude, but it passed Earth's orbit without striking the planet, missing by nine days.

🔗 Economics 🔗 Robotics 🔗 Game theory

Mechanism design is a field in economics and game theory that takes an objectives-first approach to designing economic mechanisms or incentives, toward desired objectives, in strategic settings, where players act rationally. Because it starts at the end of the game, then goes backwards, it is also called reverse game theory. It has broad applications, from economics and politics (markets, auctions, voting procedures) to networked-systems (internet interdomain routing, sponsored search auctions).

Mechanism design studies solution concepts for a class of private-information games. Leonid Hurwicz explains that 'in a design problem, the goal function is the main "given", while the mechanism is the unknown. Therefore, the design problem is the "inverse" of traditional economic theory, which is typically devoted to the analysis of the performance of a given mechanism.' So, two distinguishing features of these games are:

• that a game "designer" chooses the game structure rather than inheriting one
• that the designer is interested in the game's outcome

The 2007 Nobel Memorial Prize in Economic Sciences was awarded to Leonid Hurwicz, Eric Maskin, and Roger Myerson "for having laid the foundations of mechanism design theory".

🔗 Languages

The Dolgopolsky list is a word list compiled by Aharon Dolgopolsky in 1964. It lists the 15 lexical items that have the most semantic stability, i.e. they are the 15 words least likely to be replaced by other words as a language evolves. It was based on a study of 140 languages from across Eurasia.

The words, with the first being the most stable, are:

1. I/me
2. two/pair
3. you (singular, informal)
4. who/what
5. tongue
6. name
7. eye
8. heart
9. tooth
10. no/not
11. nail (finger-nail)
12. louse/nit
13. tear/teardrop
14. water
15. dead

The first item in the list, I/me, has been replaced in none of the 140 languages during their recorded history; the fifteenth, dead, has been replaced in 25% of the languages.

The twelfth item, louse/nit, is well kept in the North Caucasian languages, Dravidian and Turkic, but not in other proto-languages.

🔗 Physics 🔗 Physics/Fluid Dynamics

A Feynman sprinkler, also referred to as a Feynman inverse sprinkler or as a reverse sprinkler, is a sprinkler-like device which is submerged in a tank and made to suck in the surrounding fluid. The question of how such a device would turn was the subject of an intense and remarkably long-lived debate.

A regular sprinkler has nozzles arranged at angles on a freely rotating wheel such that when water is pumped out of them, the resulting jets cause the wheel to rotate; both a Catherine wheel and the aeolipile ("Hero's engine") work on the same principle. A "reverse" or "inverse" sprinkler would operate by aspirating the surrounding fluid instead. The problem is now commonly associated with theoretical physicist Richard Feynman, who mentions it in his bestselling memoirs Surely You're Joking, Mr. Feynman! The problem did not originate with Feynman, nor did he publish a solution to it.

🔗 India 🔗 India/Kerala

ka·ṭa·pa·yā·di (Devanagari: कटपयादि) system (also known as Paralppēru, Malayalam: പരല്‍പ്പേര്) of numerical notation is an ancient Indian alphasyllabic numeral system to depict letters to numerals for easy remembrance of numbers as words or verses. Assigning more than one letter to one numeral and nullifying certain other letters as valueless, this system provides the flexibility in forming meaningful words out of numbers which can be easily remembered.

🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Poland

The method of Zygalski sheets was a cryptologic technique used by the Polish Cipher Bureau before and during World War II, and during the war also by British cryptologists at Bletchley Park, to decrypt messages enciphered on German Enigma machines.

The Zygalski-sheet apparatus takes its name from Polish Cipher Bureau mathematician–cryptologist Henryk Zygalski, who invented it about October 1938.