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🔗 Physics

Wigner's friend is a thought experiment in theoretical quantum physics, first conceived by the physicist Eugene Wigner in 1961., and developed into a thought experiment by David Deutsch in 1985. The scenario involves an indirect observation of a quantum measurement: An observer W observes another observer F who performs a quantum measurement on a physical system. The two observers then formulate a statement about the physical system's state after the measurement according to the laws of quantum theory. However, in most of the interpretations of quantum theory, the resulting statements of the two observers contradict each other. This reflects a seeming incompatibility of two laws in quantum theory: the deterministic and continuous time evolution of the state of a closed system and the probabilistic, discontinuous collapse of the state of a system upon measurement. Wigner's friend is therefore directly linked to the measurement problem in quantum mechanics with its famous Schrödinger's cat paradox.

🔗 Sociology 🔗 Finland

Wiio's laws are humoristically formulated observations about how humans communicate.

Wiio's laws are usually summarized with "Human communications usually fail except by accident", which is the main observation made by Professor Osmo Antero Wiio in 1978.

🔗 Computing 🔗 Computing/Computer Security

In computing, a fork bomb (also called rabbit virus or wabbit) is a denial-of-service attack wherein a process continually replicates itself to deplete available system resources, slowing down or crashing the system due to resource starvation.

🔗 Environment 🔗 Energy

Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential energy of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost surplus off-peak electric power is typically used to run the pumps. During periods of high electrical demand, the stored water is released through turbines to produce electric power.

Pumped-storage hydroelectricity allows energy from intermittent sources (such as solar, wind) and other renewables, or excess electricity from continuous base-load sources (such as coal or nuclear) to be saved for periods of higher demand. The reservoirs used with pumped storage can be quite small when contrasted with the lakes of conventional hydroelectric plants of similar power capacity, and generating periods are often less than half a day.

The round-trip efficiency of PSH generally varies between 70%–80%. Although the losses of the pumping process make the plant a net consumer of energy overall, the system increases revenue by selling more electricity during periods of peak demand, when electricity prices are highest. If the upper lake collects significant rainfall or is fed by a river then the plant may be a net energy producer in the manner of a traditional hydroelectric plant.

Pumped storage is by far the largest-capacity form of grid energy storage available, and, as of 2020, PSH accounts for around 95% of all active storage installations worldwide, with a total installed throughput capacity of over 181 GW and a total installed storage capacity of over 1.6 TWh.

The main requirement for PSH is hilly country. The global greenfield pumped hydro atlas lists more than 600,000 potential sites around the world, which is about 100 times more than needed to support 100% renewable electricity. Most are closed-loop systems away from rivers. Areas of natural beauty and new dams on rivers can be avoided because of the very large number of potential sites. Some projects utilise existing reservoirs (dubbed "bluefield") such as the 350 Gigawatt-hour Snowy 2.0 scheme under construction in Australia. Some recently proposed projects propose to take advantage of "brownfield" locations such as disused mines such as the Kidston project under construction in Australia.

Water requirements for PSH are small: about 1 gigalitre of initial fill water per gigawatt-hour of storage. This water is recycled uphill and back downhill between the two reservoirs for many decades, but evaporation losses (beyond what rainfall and any inflow from local waterways provide) must be replaced. Land requirements are also small: about 10 hectares per gigawatt-hour of storage, which is much smaller than the land occupied by the solar and windfarms that the storage might support. Closed loop (off-river) pumped hydro storage has the smallest carbon emissions per unit of storage of all candidates for large-scale energy storage.

🔗 Mathematics

In mathematics before the 1970s, the term umbral calculus referred to the surprising similarity between seemingly unrelated polynomial equations and certain "shadowy" techniques used to "prove" them. These techniques were introduced by John Blissard (1861) and are sometimes called Blissard's symbolic method. They are often attributed to Édouard Lucas (or James Joseph Sylvester), who used the technique extensively.

🔗 Video games

The Neo Geo (Japanese: ネオジオ, Hepburn: Neojio), stylised as NEO・GEO, also written as NEOGEO, is a cartridge-based arcade system board and fourth-generation home video game console released on April 26, 1990, by Japanese game company SNK Corporation. It was the first system in SNK's Neo Geo family. The Neo Geo was marketed as 24-bit; its CPU is technically a 16/32-bit 68000-based system with an 8/16-bit Z80 coprocessor, while its GPU chipset has a 24-bit graphics data bus.

The Neo Geo originally launched as the MVS (Multi Video System) coin-operated arcade machine. The MVS offers owners the ability to put up to six different cartridges into a single cabinet, a unique feature that was also a key economic consideration for operators with limited floorspace, as well as saving money long-term. With its games stored on self-contained cartridges, a game cabinet can be exchanged for a different game title by swapping the game's ROM cartridge and cabinet artwork. A home console version was also made, called AES (Advanced Entertainment System). It was originally launched as a rental console for video game stores in Japan (called Neo Geo Rental System), with its high price causing SNK not to release it for home use – this was later reversed due to high demand and it came into the market as a luxury console. The AES had the same raw specs as the MVS and had full compatibility, thus managed to bring a true arcade experience to home users. The Neo Geo was revived along with the brand overall in December 2012 through the introduction of the Neo Geo X handheld and home system.

The Neo Geo was a very powerful system when released, more powerful than any video game console at the time, and many arcade systems such as rival Capcom's CPS, which did not surpass it until the CP System II in 1993. The Neo Geo MVS was a success during the 1990s due to the cabinet's low cost, six ROM slots, and compact size. Several successful video game series were released for the platform, such as Fatal Fury, Art of Fighting, Samurai Shodown, The King of Fighters and Metal Slug. The AES had a very niche market in Japan, though sales were very low in the U.S. due to its high price for both the hardware and software; but it has since gained a cult following and is now considered a collectable. Neo Geo hardware production lasted seven years, discontinued in 1997, whereas game software production lasted until 2004, making Neo Geo the longest supported arcade system of all time. The AES console was succeeded by the Neo Geo CD and the MVS arcade by the Hyper Neo Geo 64. As of March 1997, the Neo Geo and the Neo Geo CD combined had sold 980,000 units worldwide. In 2009, the Neo Geo was ranked 19th out of the 25 best video game consoles of all time by video game website IGN.

🔗 Technology 🔗 Business 🔗 Electronics 🔗 Energy 🔗 Home Living

The Phoebus cartel existed to control the manufacture and sale of incandescent light bulbs. They appropriated market territories and fixed the useful life of such bulbs. Corporations based in Europe and America founded the cartel on January 15, 1925 in Geneva. They had intended the cartel to last for thirty years (1925 to 1955). The cartel ceased operations in 1939 owing to the outbreak of World War II. The cartel included manufacturers Osram, General Electric, Associated Electrical Industries, and Philips, among others.

The Phoebus cartel created a notable landmark in the history of the global economy because it engaged in large-scale planned obsolescence to generate repeated sales and maximize profit. It also reduced competition in the light bulb industry for almost fifteen years. Critics accused the cartel of preventing technological advances that would produce longer-lasting light bulbs. Phoebus based itself in Switzerland. The corporation named itself Phœbus S.A. Compagnie Industrielle pour le Développement de l'Éclairage (French for "Phoebus, Inc. Industrial Company for the Development of Lighting").

🔗 Technology 🔗 Internet 🔗 Computing 🔗 Computing/Networking

An email address identifies an email box to which email messages are delivered. A wide variety of formats were used in early email systems, but only a single format is used today, following the specifications developed for Internet mail systems since the 1980s. This article uses the term email address to refer to the addr-spec defined in RFC 5322, not to the address that is commonly used; the difference is that an address may contain a display name, a comment, or both.

An email address such as John.Smith@example.com is made up of a local-part, an @ symbol, then a case-insensitive domain. Although the standard requires the local part to be case-sensitive, it also urges that receiving hosts deliver messages in a case-independent fashion, e.g., that the mail system at example.com treat John.Smith as equivalent to john.smith; some mail systems even treat them as equivalent to johnsmith. Mail systems often limit their users' choice of name to a subset of the technically valid characters, and in some cases also limit which addresses it is possible to send mail to.

With the introduction of internationalized domain names, efforts are progressing to permit non-ASCII characters in email addresses.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Military history/World War II 🔗 Firearms 🔗 Military history/European military history 🔗 Military history/British military history

The Welrod is a British bolt-action, magazine-fed pistol with an integrated silencer which was devised for covert operations during the Second World War by Major Hugh Reeves at the Inter-Services Research Bureau (later Station IX).

Station IX, being based in Welwyn, gave the Welrod its unusual name, being derived from "Wel" from "Welwyn" (a prefix used by covert equipment designed by Station IX) and "rod", gangland slang for gun, as a way to obscure its purpose.

Designed for use by irregular forces and resistance groups, the Welrod is an extremely quiet gun thanks to its integrated silencer. Approximately 2,800 were made in wartime and perhaps 14,000 in total when post-war examples are included.

🔗 Switzerland 🔗 Countries

Switzerland, officially the Swiss Confederation, is a country situated in the confluence of Western, Central, and Southern Europe. It is a federal republic composed of 26 cantons, with federal authorities seated in Bern. Switzerland is a landlocked country bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. It is geographically divided among the Swiss Plateau, the Alps, and the Jura, spanning a total area of 41,285 km² (15,940 sq mi), and land area of 39,997 km² (15,443 sq mi). While the Alps occupy the greater part of the territory, the Swiss population of approximately 8.5 million is concentrated mostly on the plateau, where the largest cities are located, among them the two global cities and economic centres of Zürich and Geneva.

The establishment of the Old Swiss Confederacy dates to the late medieval period, resulting from a series of military successes against Austria and Burgundy. Swiss independence from the Holy Roman Empire was formally recognized in the Peace of Westphalia in 1648. The Federal Charter of 1291 is considered the founding document of Switzerland which is celebrated on Swiss National Day. Since the Reformation of the 16th century, Switzerland has maintained a strong policy of armed neutrality; it has not fought an international war since 1815 and did not join the United Nations until 2002. Nevertheless, it pursues an active foreign policy and is frequently involved in peace-building processes around the world. Switzerland is the birthplace of the Red Cross, one of the world's oldest and best known humanitarian organisations, and is home to numerous international organisations, including the second largest UN office. It is a founding member of the European Free Trade Association, but notably not part of the European Union, the European Economic Area or the Eurozone. However, it participates in the Schengen Area and the European Single Market through bilateral treaties.

Switzerland occupies the crossroads of Germanic and Romance Europe, as reflected in its four main linguistic and cultural regions: German, French, Italian and Romansh. Although the majority of the population are German-speaking, Swiss national identity is rooted in a common historical background, shared values such as federalism and direct democracy, and Alpine symbolism. Due to its linguistic diversity, Switzerland is known by a variety of native names: Schweiz [ˈʃvaɪts] (German); Suisse [sɥis(ə)] (French); Svizzera [ˈzvittsera] (Italian); and Svizra [ˈʒviːtsrɐ, ˈʒviːtsʁɐ] (Romansh). On coins and stamps, the Latin name, Confoederatio Helvetica – frequently shortened to "Helvetia" – is used instead of the four national languages.

The sovereign state is one of the most developed countries in the world, with the highest nominal wealth per adult and the eighth-highest per capita gross domestic product. It ranks at or near the top in several international metrics, including economic competitiveness and human development. Zürich, Geneva and Basel have been ranked among the top ten cities in the world in terms of quality of life, with Zürich ranked second globally. In 2019, IMD placed Switzerland first in the world in attracting skilled workers. World Economic Forum ranks it the 5th most competitive country globally.