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🔗 Mathematics

In geometric topology, the Clifford torus is the simplest and most symmetric flat embedding of the cartesian product of two circles S¹_a and S¹_b (in the same sense that the surface of a cylinder is "flat"). It is named after William Kingdon Clifford. It resides in R⁴, as opposed to in R³. To see why R⁴ is necessary, note that if S¹_a and S¹_b each exist in their own independent embedding spaces R²_a and R²_b, the resulting product space will be R⁴ rather than R³. The historically popular view that the cartesian product of two circles is an R³ torus in contrast requires the highly asymmetric application of a rotation operator to the second circle, since that circle will only have one independent axis z available to it after the first circle consumes x and y.

Stated another way, a torus embedded in R³ is an asymmetric reduced-dimension projection of the maximally symmetric Clifford torus embedded in R⁴. The relationship is similar to that of projecting the edges of a cube onto a sheet of paper. Such a projection creates a lower-dimensional image that accurately captures the connectivity of the cube edges, but also requires the arbitrary selection and removal of one of the three fully symmetric and interchangeable axes of the cube.

If S¹_a and S¹_b each has a radius of ${\displaystyle \textstyle {\sqrt {1/2}}}$, their Clifford torus product will fit perfectly within the unit 3-sphere S³, which is a 3-dimensional submanifold of R⁴. When mathematically convenient, the Clifford torus can be viewed as residing inside the complex coordinate space C², since C² is topologically equivalent to R⁴.

The Clifford torus is an example of a square torus, because it is isometric to a square with opposite sides identified. It is further known as a Euclidean 2-torus (the "2" is its topological dimension); figures drawn on it obey Euclidean geometry as if it were flat, whereas the surface of a common "doughnut"-shaped torus is positively curved on the outer rim and negatively curved on the inner. Although having a different geometry than the standard embedding of a torus in three-dimensional Euclidean space, the square torus can also be embedded into three-dimensional space, by the Nash embedding theorem; one possible embedding modifies the standard torus by a fractal set of ripples running in two perpendicular directions along the surface.

🔗 United States 🔗 Biography 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Lists 🔗 Military history/World War I 🔗 Military history/World War II 🔗 Military history/American Civil War 🔗 Project-independent assessment

The following is a list of Irish-American soldiers, sailors, airmen and Marines who were awarded the American military's highest decoration — the Medal of Honor. The Medal of Honor is bestowed "for conspicuous gallantry and intrepidity at the risk of life, above and beyond the call of duty, in actual combat against an armed enemy force." The medal is awarded by the President of the United States on behalf of the Congress.

Of the 3,464 Medals of Honor awarded as of September 17, 2009, an estimated 2,021 (58%) have been awarded to Irish-American recipients, more than twice the number awarded any other ethnic group; 257 Irish-born Americans have received the Medal of Honor which represents more than half of foreign-born MOH recipients. A monument to these Irish-born Medal of Honor recipients is located at Valley Forge's Medal of Honor Grove; erected by the Ancient Order of Hibernians. The first Irish American to receive the Medal was Michael Madden, who received it for his actions in the American Civil War (Note that the earliest action for which the Medal of Honor was awarded was to Irish American U.S. Army Assistant Surgeon Bernard J.D. Irwin for the engagement at Apache Pass, February 1861. The award was made three decades after the event and after Madden's award).

🔗 Medicine 🔗 Ancient Egypt

The Ebers Papyrus, also known as Papyrus Ebers, is an Egyptian medical papyrus of herbal knowledge dating to circa 1550 BC. Among the oldest and most important medical papyri of ancient Egypt, it was purchased at Luxor in the winter of 1873–74 by Georg Ebers. It is currently kept at the library of the University of Leipzig, in Germany.

🔗 California 🔗 Technology 🔗 Politics 🔗 Objectivism 🔗 Politics/Libertarianism

"The Californian Ideology" is a 1995 essay by English media theorists Richard Barbrook and Andy Cameron of the University of Westminster. Barbrook describes it as a "critique of dotcom neoliberalism". In the essay, Barbrook and Cameron argue that the rise of networking technologies in Silicon Valley in the 1990s was linked to American neoliberalism and a paradoxical hybridization of beliefs from the political left and right in the form of hopeful technological determinism.

The original essay was published in Mute magazine in 1995 and later appeared on the nettime Internet mailing list for debate. A final version was published in Science as Culture in 1996. The critique has since been revised in several different versions and languages.

Andrew Leonard of Salon called Barbrook & Cameron's work "one of the most penetrating critiques of neo-conservative digital hypesterism yet published."

🔗 History 🔗 Physics 🔗 Telecommunications 🔗 Skepticism 🔗 Astronomy 🔗 History of Science 🔗 Physics/History 🔗 Paranormal

The Wow! signal was a strong narrowband radio signal received on August 15, 1977, by Ohio State University's Big Ear radio telescope in the United States, then used to support the search for extraterrestrial intelligence. The signal appeared to come from the direction of the constellation Sagittarius and bore the expected hallmarks of extraterrestrial origin.

Astronomer Jerry R. Ehman discovered the anomaly a few days later while reviewing the recorded data. He was so impressed by the result that he circled the reading on the computer printout, "6EQUJ5", and wrote the comment "Wow!" on its side, leading to the event's widely used name.

The entire signal sequence lasted for the full 72-second window during which Big Ear was able to observe it, but has not been detected since, despite several subsequent attempts by Ehman and others. Many hypotheses have been advanced on the origin of the emission, including natural and human-made sources, but none of them adequately explains the signal.

Although the Wow! signal had no detectable modulation—a technique used to transmit information over radio waves—it remains the strongest candidate for an alien radio transmission ever detected.

🔗 Computing 🔗 Computing/Computer hardware

Viewtron was an online service offered by Knight-Ridder and AT&T from 1983 to 1986. Patterned after the British Post Office's Prestel system, it started as a videotex service requiring users to have a special terminal, the AT&T Sceptre. As home computers became important in the marketplace, the development focus shifted to IBM, Apple, Commodore and other personal computers.

Viewtron differed from contemporary services like CompuServe and The Source by emphasizing news from The Miami Herald and Associated Press and e-commerce services from JCPenney and other merchants over computer-oriented services such as file downloads or online chat. Intended to be "the McDonald's of videotex," Viewtron was specifically targeted toward users who would be apprehensive about using a computer.

Viewtron also offered airline schedules from the Official Airline Guide (OAG), real estate research from Century 21, e-cards from Hallmark, product information from Consumer Reports, educational software from Scott Foresman, online auctions, financial services from American Express and EF Hutton, as well as limited online banking services as part of a research program into the uses and costs of banking online that included 20 US and Canadian banks.

At its height, Viewtron was operated in at least 15 cities by various newspaper companies. After six years of research and an investment reportedly in excess of $50 million, Viewtron never turned a profit, and, despite its developer's forecasts of breaking even in two years, Knight Ridder did not expect it ever would be profitable. AT&T had invested over $100 million in the project, but was forced to write off that investment as part of its court-ordered breakup. Viewtron closed on March 31, 1986, after an attempt by the Independent Commodore Users Group to buy the service failed.

A feature tying Viewtron to local newspapers was envisioned, with printed text instructing users how to access further information online, but it was never implemented.

In 2008, PCWorld magazine named Viewtron to a list of the biggest project failures in information technology (IT) history.

🔗 Philosophy 🔗 Philosophy/Logic 🔗 Philosophy/Metaphysics

Dialetheism (from Greek δι- di- 'twice' and ἀλήθεια alḗtheia 'truth') is the view that there are statements that are both true and false. More precisely, it is the belief that there can be a true statement whose negation is also true. Such statements are called "true contradictions", dialetheia, or nondualisms.

Dialetheism is not a system of formal logic; instead, it is a thesis about truth that influences the construction of a formal logic, often based on pre-existing systems. Introducing dialetheism has various consequences, depending on the theory into which it is introduced. A common mistake resulting from this is to reject dialetheism on the basis that, in traditional systems of logic (e.g., classical logic and intuitionistic logic), every statement becomes a theorem if a contradiction is true, trivialising such systems when dialetheism is included as an axiom. Other logical systems, however, do not explode in this manner when contradictions are introduced; such contradiction-tolerant systems are known as paraconsistent logics. Dialetheists who do not want to allow that every statement is true are free to favour these over traditional, explosive logics.

Graham Priest defines dialetheism as the view that there are true contradictions. Jc Beall is another advocate; his position differs from Priest's in advocating constructive (methodological) deflationism regarding the truth predicate.

🔗 Chess

Los Alamos chess (or anti-clerical chess) is a chess variant played on a 6×6 board without bishops. This was the first chess-like game played by a computer program. This program was written at Los Alamos Scientific Laboratory by Paul Stein and Mark Wells for the MANIAC I computer in 1956. The reduction of the board size and the number of pieces from standard chess was due to the very limited capacity of computers at the time.

The program was very simple, containing only about 600 instructions. It was mostly a minimax tree search and could look four plies ahead. For scoring the board at the end of the four-ply lookahead, it estimates a score for material and a score for mobility, then adds them up. Pseudocode for the chess program is described in Figure 11.4 of Newell, 2019. In 1958, a revised version was written for MANIAC II for full 8×8 chess, though its pseudocode was never published. There is a record of a single game by it, circa November 1958 (Table 11.2 of Newell, 2019).

🔗 Military history 🔗 Futures studies 🔗 Military history/Cold War 🔗 Cold War

World War III or the Third World War, often abbreviated as WWIII or WW3, are names given to a hypothetical third worldwide large-scale military conflict after World War I and World War II. The term has been in use since at least as early as 1941. Some apply it loosely to limited or more minor conflicts such as the Cold War or the war on terror. In contrast, others assume that such a conflict would surpass prior world wars in both scope and destructive impact.

Due to the development and use of nuclear weapons near the end of World War II and their subsequent acquisition and deployment by many countries, the potential risk of a nuclear apocalypse causing widespread destruction of Earth's civilization and life is a common theme in speculations about a Third World War. Another primary concern is that biological warfare could cause many casualties. It could happen intentionally or inadvertently, by an accidental release of a biological agent, the unexpected mutation of an agent, or its adaptation to other species after use. Large-scale apocalyptic events like these, caused by advanced technology used for destruction, could render Earth's surface uninhabitable.

Before the beginning of World War II in 1939, World War I (1914–1918) was believed to have been "the war to end [all] wars." It was popularly believed that never again could there possibly be a global conflict of such magnitude. During the interwar period, World War I was typically referred to simply as "The Great War". The outbreak of World War II disproved the hope that humanity might have already "outgrown" the need for such widespread global wars.

With the advent of the Cold War in 1945 and with the spread of nuclear weapons technology to the Soviet Union, the possibility of a third global conflict became more plausible. During the Cold War years, the possibility of a Third World War was anticipated and planned for by military and civil authorities in many countries. Scenarios ranged from conventional warfare to limited or total nuclear warfare. At the height of the Cold War, the doctrine of mutually assured destruction (MAD), which determined an all-out nuclear confrontation would destroy all of the states involved in the conflict, had been developed. The absolute potential destruction of the human race may have contributed to the ability of both American and Soviet leaders to avoid such a scenario.

🔗 Technology 🔗 Energy

A solar pond is a pool of saltwater which collects and stores solar thermal energy. The saltwater naturally forms a vertical salinity gradient also known as a "halocline", in which low-salinity water floats on top of high-salinity water. The layers of salt solutions increase in concentration (and therefore density) with depth. Below a certain depth, the solution has a uniformly high salt concentration.