Have a deep view into what people are curious about.

🔗 Mathematics

In geometry, the problem of dividing a circle into areas by means of an inscribed polygon with n sides in such a way as to maximise the number of areas created by the edges and diagonals, sometimes called Moser's circle problem, has a solution by an inductive method. The greatest possible number of regions, r_G = ( ⁿ
₄ ) + ( ⁿ
₂ ) + 1, giving the sequence 1, 2, 4, 8, 16, 31, 57, 99, 163, 256, ... (OEIS: A000127). Though the first five terms match the geometric progression 2^{n − 1}, it diverges at n = 6, showing the risk of generalising from only a few observations.

Reasons for my No consensus closure of Wikipedia:Articles for deletion/Dwm (2nd nomination)

If you want to make any comments or ask questions about this closure, please use User talk:Flyguy649/Dwm rather than my talk page. I hope the community can live with my decision; if not, there is deletion review.

🔗 Denmark 🔗 Folklore

The Elder Mother is an elder-guarding being in English and Scandinavian folklore known by a variety of names, such as the Danish Hyldemoer ("Elder-Mother") and the Lincolnshire names Old Lady and Old Girl.

🔗 Astronomy 🔗 Astronomy/Astronomical objects

Tabby's Star (also known as Boyajian's Star and WTF Star, and designated KIC 8462852 in the Kepler Input Catalog) is an F-type main-sequence star in the constellation Cygnus approximately 1,470 light-years (450 pc) from Earth. Unusual light fluctuations of the star, including up to a 22% dimming in brightness, were discovered by citizen scientists as part of the Planet Hunters project. In September 2015, astronomers and citizen scientists associated with the project posted a preprint of an article describing the data and possible interpretations. The discovery was made from data collected by the Kepler space telescope, which observed changes in the brightness of distant stars to detect exoplanets.

Several hypotheses have been proposed to explain the star's large irregular changes in brightness as measured by its light curve, but none to date fully explain all aspects of the curve. One explanation is that an "uneven ring of dust" orbits Tabby's Star. In another explanation, the star's luminosity is modulated by changes in the efficiency of heat transport to its photosphere, so no external obscuration is required. A third hypothesis, based on a lack of observed infrared light, posits a swarm of cold, dusty comet fragments in a highly eccentric orbit; however, the notion that disturbed comets from such a cloud could exist in high enough numbers to obscure 22% of the star's observed luminosity has been doubted. Another hypothesis is that a large number of small masses in "tight formation" are orbiting the star. Furthermore, spectroscopic study of the system has found no evidence for coalescing material or hot close-in dust or circumstellar matter from an evaporating or exploding planet within a few astronomical units of the mature central star. It has also been hypothesized that the changes in brightness could be signs of activity associated with intelligent extraterrestrial life constructing a Dyson swarm; however, further analysis based on data through the end of 2017 showed wavelength-dependent dimming consistent with dust but not an opaque object such as an alien megastructure, which would block all wavelengths of light equally.

Tabby's Star is not the only star that has large irregular dimmings, but other such stars include young stellar objects called YSO dippers, which have different dimming patterns. An example of such an object is EPIC 204278916.

New fluctuations ran from mid-May 2017 until July 2018, assuming their continuance in late-December 2017 to mid-February 2018 when obscured by the Sun.

In September 2019, astronomers reported that the observed dimmings of Tabby's Star may have been produced by fragments resulting from the disruption of an orphaned exomoon. An overall study of other similar stars has been presented. In January 2021, a distant stellar-mass companion was reported, making Tabby's Star a binary stellar system.

🔗 United States 🔗 United States/North Carolina 🔗 Aviation 🔗 Military history 🔗 Disaster management 🔗 Military history/Military aviation 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 United States/Military history - U.S. military history 🔗 Aviation/Aviation accident 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry

The 1961 Goldsboro B-52 crash was an accident that occurred near Goldsboro, North Carolina, on 23 January 1961. A Boeing B-52 Stratofortress carrying two 3–4-megaton Mark 39 nuclear bombs broke up in mid-air, dropping its nuclear payload in the process. The pilot in command, Walter Scott Tulloch, ordered the crew to eject at 9,000 feet (2,700 m). Five crewmen successfully ejected or bailed out of the aircraft and landed safely, another ejected, but did not survive the landing, and two died in the crash. Information declassified in 2013 showed that one of the bombs came very close to detonating.

🔗 Game theory

The Price of Anarchy (PoA) is a concept in economics and game theory that measures how the efficiency of a system degrades due to selfish behavior of its agents. It is a general notion that can be extended to diverse systems and notions of efficiency. For example, consider the system of transportation of a city and many agents trying to go from some initial location to a destination. Let efficiency in this case mean the average time for an agent to reach the destination. In the 'centralized' solution, a central authority can tell each agent which path to take in order to minimize the average travel time. In the 'decentralized' version, each agent chooses its own path. The Price of Anarchy measures the ratio between average travel time in the two cases.

Usually the system is modeled as a game and the efficiency is some function of the outcomes (e.g. maximum delay in a network, congestion in a transportation system, social welfare in an auction, ...). Different concepts of equilibrium can be used to model the selfish behavior of the agents, among which the most common is the Nash equilibrium. Different flavors of Nash equilibrium lead to variations of the notion of Price of Anarchy as Pure Price of Anarchy (for deterministic equilibria), Mixed Price of Anarchy (for randomized equilibria), and Bayes–Nash Price of Anarchy (for games with incomplete information). Solution concepts other than Nash equilibrium lead to variations such as the Price of Sinking.

The term Price of Anarchy was first used by Elias Koutsoupias and Christos Papadimitriou, but the idea of measuring inefficiency of equilibrium is older. The concept in its current form was designed to be the analogue of the 'approximation ratio' in an approximation algorithm or the 'competitive ratio' in an online algorithm. This is in the context of the current trend of analyzing games using algorithmic lenses (algorithmic game theory).

Meta is a company performing big data analysis of scientific literature. Company is headquartered in Redwood City, California (formerly Toronto, Ontario, Canada) and operates Meta Science, a literature discovery platform. The company was acquired by the Chan Zuckerberg Initiative in 2017.

🔗 United States/U.S. Government 🔗 United States 🔗 Mass surveillance 🔗 Cryptography 🔗 Cryptography/Computer science

The Clipper chip was a chipset that was developed and promoted by the United States National Security Agency (NSA) as an encryption device that secured “voice and data messages" with a built-in backdoor. It was intended to be adopted by telecommunications companies for voice transmission. It can encipher and decipher messages. It was part of a Clinton Administration program to “allow Federal, State, and local law enforcement officials the ability to decode intercepted voice and data transmissions." “Each clipper chip ha[d] a unique serial number and a secret ‘unit key,’ programmed into the chip when manufactured." This way, each device was meant to be different from the next.

It was announced in 1993 and by 1996 was entirely defunct.

🔗 Aviation 🔗 Norway 🔗 Arctic 🔗 Sweden

Andrée's Arctic balloon expedition of 1897 was an effort to reach the North Pole in which all three Swedish expedition members – S. A. Andrée, Knut Frænkel, and Nils Strindberg – perished. Andrée, the first Swedish balloonist, proposed a voyage by hydrogen balloon from Svalbard to either Russia or Canada, which was to pass, with luck, straight over the North Pole on the way. The scheme was received with patriotic enthusiasm in Sweden, a northern nation that had fallen behind in the race for the North Pole.

Andrée ignored many early signs of the dangers associated with his balloon plan. Being able to steer the balloon to some extent was essential for a safe journey, but there was much evidence that the drag-rope steering technique he had invented was ineffective. Worse, the polar balloon Örnen (Eagle) was delivered directly to Svalbard from its manufacturer in Paris without being tested. When measurements showed it to be leaking more than expected, Andrée failed to acknowledge the risk.

After Andrée, Strindberg, and Frænkel lifted off from Svalbard in July 1897, the balloon lost hydrogen quickly and crashed on the pack ice after only two days. The explorers were unhurt but faced a grueling trek back south across the drifting icescape. Inadequately clothed, equipped, and prepared, and shocked by the difficulty of the terrain, they did not make it to safety. As the Arctic winter closed in on them in October, the group ended up exhausted on the deserted Kvitøya (White Island) in Svalbard and died there. For 33 years the fate of the expedition remained one of the unsolved riddles of the Arctic. The chance discovery in 1930 of the expedition's last camp created a media sensation in Sweden, where the dead men had been mourned and idolized.

Andrée's motives and mindset have been the subject of extensive fictional and historical discussion, particularly inspired by his apparent foolhardiness. An early example is Per Olof Sundman's fictionalized bestseller novel of 1967, The Flight of the Eagle, which portrays Andrée as weak and cynical, at the mercy of his sponsors and the media. Modern writers have been generally critical of Andrée.