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🔗 Soviet Union 🔗 Russia 🔗 Disaster management 🔗 Skepticism 🔗 Astronomy 🔗 Russia/science and education in Russia 🔗 Geology 🔗 Russia/physical geography of Russia 🔗 Russia/history of Russia 🔗 Paranormal

The Tunguska event was a massive ~12 megaton explosion that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of June 30, 1908. The explosion over the sparsely populated Eastern Siberian Taiga flattened an estimated 80 million trees over an area of 2,150 km² (830 sq mi) of forest, and eyewitness reports suggest that at least three people may have died in the event. The explosion is generally attributed to the air burst of a stony meteoroid about 50–60 metres (160–200 feet) in size.^{: p. 178} The meteoroid approached from the east-southeast, and likely with a relatively high speed of about 27 km/s. It is classified as an impact event, even though no impact crater has been found; the object is thought to have disintegrated at an altitude of 5 to 10 kilometres (3 to 6 miles) rather than to have hit the surface of the Earth.

The Tunguska event is the largest impact event on Earth in recorded history, though much larger impacts have occurred in prehistoric times. An explosion of this magnitude would be capable of destroying a large metropolitan area. It has been mentioned numerous times in popular culture, and has also inspired real-world discussion of asteroid impact avoidance.

🔗 Computing 🔗 Systems 🔗 Business 🔗 Computing/Software 🔗 Computing/Computer science 🔗 Engineering 🔗 Systems/Systems engineering

Hofstadter's law is a self-referential adage, coined by Douglas Hofstadter in his book Gödel, Escher, Bach: An Eternal Golden Braid (1979) to describe the widely experienced difficulty of accurately estimating the time it will take to complete tasks of substantial complexity:

Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law.

The law is often cited by programmers in discussions of techniques to improve productivity, such as The Mythical Man-Month or extreme programming.

🔗 United States 🔗 Politics 🔗 Politics/American politics 🔗 Elections and Referendums 🔗 United States/U.S. presidential elections

The 1876 United States presidential election was the 23rd quadrennial presidential election, held on Tuesday, November 7, 1876, in which Republican nominee Rutherford B. Hayes faced Democrat Samuel J. Tilden. It was one of the most contentious and controversial presidential elections in American history, and gave rise to the Compromise of 1877 by which the Democrats conceded the election to Hayes in return for an end to Reconstruction and the withdrawal of federal troops from the South. After a controversial post-election process, Hayes was declared the winner.

After President Ulysses S. Grant declined to seek a third term despite previously being expected to do so, Congressman James G. Blaine emerged as the front-runner for the Republican nomination. However, Blaine was unable to win a majority at the 1876 Republican National Convention, which settled on Governor Hayes of Ohio as a compromise candidate. The 1876 Democratic National Convention nominated Governor Tilden of New York on the second ballot.

The results of the election remain among the most disputed ever. Although it is not disputed that Tilden outpolled Hayes in the popular vote, after a first count of votes, Tilden had won 184 electoral votes to Hayes's 165, with 20 votes from four states unresolved: in Florida, Louisiana, and South Carolina, each party reported its candidate had won the state, while in Oregon, one elector was replaced after being declared illegal for being an "elected or appointed official". The question of who should have been awarded these electoral votes is the source of the continued controversy.

An informal deal was struck to resolve the dispute: the Compromise of 1877, which awarded all 20 electoral votes to Hayes; in return for the Democrats' acquiescence to Hayes' election, the Republicans agreed to withdraw federal troops from the South, ending Reconstruction. The Compromise in effect ceded power in the Southern states to the Democratic Redeemers, who proceeded to disenfranchise black voters thereafter.

The 1876 election is the second of five presidential elections in which the person who won the most popular votes did not win the election, but the only such election in which the popular vote winner received a majority (rather than a plurality) of the popular vote. To date, it remains the election that recorded the smallest electoral vote victory (185–184), and the election that yielded the highest voter turnout of the eligible voting age population in American history, at 81.8%. Despite not becoming president, Tilden was the first Democratic presidential nominee since James Buchanan in 1856 to win the popular vote and the first since Franklin Pierce in 1852 to do so in an outright majority (In fact, Tilden received a slightly higher percentage than Pierce in 1852, despite the fact that Pierce won in a landslide).

🔗 Food and drink 🔗 Birds

A chicken can be hypnotized, or put into a trance, by holding its head down against the ground, and drawing a line along the ground with a stick or a finger, starting at the beak and extending straight outward in front of the chicken. If the chicken is hypnotized in this manner, it will continue to stare at the line, remaining immobile for as long as 30 minutes. Other methods of inducing this state are also known. Ethologists refer to this state as 'tonic immobility' i.e. a natural state of semi-paralysis that some animals enter when presented with a threat, which is probably a defensive mechanism intended to feign death, albeit rather poorly.

The first known written reference for this method came in 1646, in Mirabele Experimentum de Imaginatione Gallinae by Athanasius Kircher in Rome.

🔗 Computing 🔗 Computing/Computer hardware

PLATO (Programmed Logic for Automatic Teaching Operations) was the first generalized computer-assisted instruction system. Starting in 1960, it ran on the University of Illinois' ILLIAC I computer. By the late 1970s, it supported several thousand graphics terminals distributed worldwide, running on nearly a dozen different networked mainframe computers. Many modern concepts in multi-user computing were originally developed on PLATO, including forums, message boards, online testing, e-mail, chat rooms, picture languages, instant messaging, remote screen sharing, and multiplayer video games.

PLATO was designed and built by the University of Illinois and functioned for four decades, offering coursework (elementary through university) to UIUC students, local schools, and other universities. Courses were taught in a range of subjects, including Latin, chemistry, education, music, and primary mathematics. The system included a number of features useful for pedagogy, including text overlaying graphics, contextual assessment of free-text answers, depending on the inclusion of keywords, and feedback designed to respond to alternative answers.

Rights to market PLATO as a commercial product were licensed by Control Data Corporation (CDC), the manufacturer on whose mainframe computers the PLATO IV system was built. CDC President William Norris planned to make PLATO a force in the computer world, but found that marketing the system was not as easy as hoped. PLATO nevertheless built a strong following in certain markets, and the last production PLATO system did not shut down until 2006, coincidentally just a month after Norris died.

🔗 Internet culture

In Internet culture, the 1% rule is a rule of thumb pertaining to participation in an internet community, stating that only 1% of the users of a website add content, while the other 99% of the participants only lurk. Variants include the 1–9–90 rule (sometimes 90–9–1 principle or the 89:10:1 ratio), which states that in a collaborative website such as a wiki, 90% of the participants of a community only consume content, 9% of the participants change or update content, and 1% of the participants add content.

Similar rules are known in information science, such as the 80/20 rule known as the Pareto principle, that 20 percent of a group will produce 80 percent of the activity, however the activity may be defined.

🔗 Cognitive science 🔗 Neuroscience

Sparse distributed memory (SDM) is a mathematical model of human long-term memory introduced by Pentti Kanerva in 1988 while he was at NASA Ames Research Center. It is a generalized random-access memory (RAM) for long (e.g., 1,000 bit) binary words. These words serve as both addresses to and data for the memory. The main attribute of the memory is sensitivity to similarity, meaning that a word can be read back not only by giving the original write address but also by giving one close to it, as measured by the number of mismatched bits (i.e., the Hamming distance between memory addresses).

SDM implements transformation from logical space to physical space using distributed data representation and storage, similarly to encoding processes in human memory. A value corresponding to a logical address is stored into many physical addresses. This way of storing is robust and not deterministic. A memory cell is not addressed directly. If input data (logical addresses) are partially damaged at all, we can still get correct output data.

The theory of the memory is mathematically complete and has been verified by computer simulation. It arose from the observation that the distances between points of a high-dimensional space resemble the proximity relations between concepts in human memory. The theory is also practical in that memories based on it can be implemented with conventional RAM-memory elements.

🔗 Germany 🔗 Germany/Hamburg 🔗 Germany/German transportation

Old Elbe Tunnel or St. Pauli Elbe Tunnel (German: Alter Elbtunnel colloquially or St. Pauli Elbtunnel officially) which opened in 1911, is a pedestrian and vehicle tunnel in Hamburg. The 426 m (1,398 ft) long tunnel was a technical sensation; 24 m (80 ft) beneath the surface, two 6 m (20 ft) diameter tubes connect central Hamburg with the docks and shipyards on the south side of the river Elbe. This was a big improvement for tens of thousands of workers in one of the busiest harbors in the world.

Six large lifts on either side of the tunnel carry pedestrians and vehicles to the bottom. The two tunnels are both still in operation, though due to their limited capacity by today's standards, other bridges and tunnels have been built and taken over most of the traffic.

In 2008 approximately 300,000 cars, 63,000 bicycles, and 700,000 pedestrians used the tunnel. The tunnel is opened 24 hours for pedestrians and bicycles. For motorized vehicles, opening times are currently Monday to Friday from 5:20 a.m. to 8:00 p.m. and on Saturdays from 5:20 a.m. to 4:00 p.m.

🔗 Mathematics

The dangerous bend or caution symbol ☡ (U+2621 ☡ CAUTION SIGN) was created by the Nicolas Bourbaki group of mathematicians and appears in the margins of mathematics books written by the group. It resembles a road sign that indicates a "dangerous bend" in the road ahead, and is used to mark passages tricky on a first reading or with an especially difficult argument.

🔗 Biography 🔗 Internet 🔗 Computing 🔗 Philosophy 🔗 Biography/science and academia 🔗 Philosophy/Philosophers 🔗 Sociology 🔗 University of Oxford

Theodor Holm Nelson (born June 17, 1937) is an American pioneer of information technology, philosopher and sociologist. He coined the terms hypertext and hypermedia in 1963 and published them in 1965. Nelson coined the terms transclusion, virtuality, and intertwingularity (in Literary Machines), and teledildonics. According to a 1997 Forbes profile, Nelson "sees himself as a literary romantic, like a Cyrano de Bergerac, or 'the Orson Welles of software.'"