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π Mathematical Coincidence
A mathematical coincidence is said to occur when two expressions with no direct relationship show a near-equality which has no apparent theoretical explanation.
For example, there is a near-equality close to the round number 1000 between powers of 2 and powers of 10:
Some mathematical coincidences are used in engineering when one expression is taken as an approximation of another.
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- "Mathematical Coincidence" | 2021-07-15 | 12 Upvotes 8 Comments
π Wikimedia Foundation ousts, bans quarter of Arabic Wikipedia admins
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- "Wikimedia Foundation ousts, bans quarter of Arabic Wikipedia admins" | 2023-01-02 | 44 Upvotes 13 Comments
π Sinking of the Rainbow Warrior
The sinking of the Rainbow Warrior, codenamed OpΓ©ration Satanique, was a bombing operation by the "action" branch of the French foreign intelligence services, the Direction gΓ©nΓ©rale de la sΓ©curitΓ© extΓ©rieure (DGSE), carried out on 10 July 1985. During the operation, two operatives sank the flagship of the Greenpeace fleet, the Rainbow Warrior, at the Port of Auckland in New Zealand on its way to a protest against a planned French nuclear test in Moruroa. Fernando Pereira, a photographer, drowned on the sinking ship.
France initially denied responsibility, but two French agents were captured by New Zealand Police and charged with arson, conspiracy to commit arson, willful damage, and murder. As the truth came out, the scandal resulted in the resignation of the French Defence Minister Charles Hernu. The two agents pleaded guilty to manslaughter and were sentenced to ten years in prison. They spent a little over two years confined to the French island of Hao before being freed by the French government.
Several political figures, including then New Zealand Prime Minister David Lange, have referred to the bombing as an act of terrorism or state-sponsored terrorism.
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- "Sinking of the Rainbow Warrior" | 2015-07-10 | 18 Upvotes 2 Comments
π Goodsteins theorem
In mathematical logic, Goodstein's theorem is a statement about the natural numbers, proved by Reuben Goodstein in 1944, which states that every Goodstein sequence eventually terminates at 0. Laurence Kirby and Jeff Paris showed that it is unprovable in Peano arithmetic (but it can be proven in stronger systems, such as second-order arithmetic). This was the third example of a true statement about natural numbers that is unprovable in Peano arithmetic, after the examples provided by GΓΆdel's incompleteness theorem and Gerhard Gentzen's 1943 direct proof of the unprovability of Ξ΅0-induction in Peano arithmetic. The ParisβHarrington theorem gave another example.
Kirby and Paris introduced a graph-theoretic hydra game with behavior similar to that of Goodstein sequences: the "Hydra" (named for the mythological multi-headed Hydra of Lerna) is a rooted tree, and a move consists of cutting off one of its "heads" (a branch of the tree), to which the hydra responds by growing a finite number of new heads according to certain rules. Kirby and Paris proved that the Hydra will eventually be killed, regardless of the strategy that Hercules uses to chop off its heads, though this may take a very long time. Just like for Goodstein sequences, Kirby and Paris showed that it cannot be proven in Peano arithmetic alone.
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- "Goodsteins theorem" | 2023-12-23 | 83 Upvotes 51 Comments
π Dadda Multiplier
The Dadda multiplier is a hardware binary multiplier design invented by computer scientist Luigi Dadda in 1965. It uses a selection of full and half adders to sum the partial products in stages (the Dadda tree or Dadda reduction) until two numbers are left. The design is similar to the Wallace multiplier, but the different reduction tree reduces the required number of gates (for all but the smallest operand sizes) and makes it slightly faster (for all operand sizes).
Dadda and Wallace multipliers have the same three steps for two bit strings and of lengths and respectively:
- Multiply (logical AND) each bit of , by each bit of , yielding results, grouped by weight in columns
- Reduce the number of partial products by stages of full and half adders until we are left with at most two bits of each weight.
- Add the final result with a conventional adder.
As with the Wallace multiplier, the multiplication products of the first step carry different weights reflecting the magnitude of the original bit values in the multiplication. For example, the product of bits has weight .
Unlike Wallace multipliers that reduce as much as possible on each layer, Dadda multipliers attempt to minimize the number of gates used, as well as input/output delay. Because of this, Dadda multipliers have a less expensive reduction phase, but the final numbers may be a few bits longer, thus requiring slightly bigger adders.
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- "Dadda Multiplier" | 2022-10-02 | 37 Upvotes 7 Comments
π Children of Men
Children of Men is a 2006 dystopian action thriller film co-written and directed by Alfonso CuarΓ³n. The screenplay, based on P. D. James' 1992 novel The Children of Men, was credited to five writers, with Clive Owen making uncredited contributions. The film takes place in 2027, when two decades of human infertility have left society on the brink of collapse. Asylum seekers seek sanctuary in the United Kingdom, where they are subjected to detention and refoulement by the government. Owen plays civil servant Theo Faron, who must help refugee Kee (Clare-Hope Ashitey) escape the chaos. Children of Men also stars Julianne Moore, Chiwetel Ejiofor, Pam Ferris, Charlie Hunnam, and Michael Caine.
The film was released by Universal Pictures on 22 September 2006 in the UK and on 25 December in the US. Critics noted the relationship between the US' Christmas opening and the film's themes of hope, redemption, and faith. Despite the limited release and lack of any clear marketing strategy during awards season by the film's distributor, Children of Men received critical acclaim and was recognised for its achievements in screenwriting, cinematography, art direction, and innovative single-shot action sequences. It was nominated for three Academy Awards: Best Adapted Screenplay, Best Cinematography, and Best Film Editing. It was also nominated for three BAFTA Awards, winning Best Cinematography and Best Production Design, and for three Saturn Awards, winning Best Science Fiction Film. In 2016 it was voted 13th among 100 films considered the best of the 21st century by 117 film critics from around the world.
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- "Children of Men" | 2022-11-15 | 38 Upvotes 21 Comments
π Wolf 359
Wolf 359 is a red dwarf star located in the constellation Leo, near the ecliptic. At a distance of approximately 7.9 light years from Earth, it has an apparent magnitude of 13.54 and can only be seen with a large telescope. Wolf 359 is one of the nearest stars to the Sun; only the Alpha Centauri system (including Proxima Centauri), Barnard's Star and the brown dwarfs Luhman 16 and WISE 0855β0714 are known to be closer. Its proximity to Earth has led to its mention in several works of fiction.
Wolf 359 is one of the faintest and lowest-mass stars known. At the light-emitting layer called the photosphere, it has a temperature of about 2,800Β K, which is low enough for chemical compounds to form and survive. The absorption lines of compounds such as water and titanium(II) oxide have been observed in the spectrum. The surface has a magnetic field that is stronger than the average magnetic field on the Sun. As a result of magnetic activity caused by convection, Wolf 359 is a flare star that can undergo sudden increases in luminosity for several minutes. These flares emit strong bursts of X-ray and gamma ray radiation that have been observed by space telescopes. Wolf 359 is a relatively young star with an age of less than a billion years. Two planetary companions are suspected but as yet no debris disks have been unmasked.
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- "Wolf 359" | 2019-12-23 | 84 Upvotes 49 Comments
π Computer
A computer is a machine that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming. Modern computers have the ability to follow generalized sets of operations, called programs. These programs enable computers to perform an extremely wide range of tasks. A "complete" computer including the hardware, the operating system (main software), and peripheral equipment required and used for "full" operation can be referred to as a computer system. This term may as well be used for a group of computers that are connected and work together, in particular a computer network or computer cluster.
Computers are used as control systems for a wide variety of industrial and consumer devices. This includes simple special purpose devices like microwave ovens and remote controls, factory devices such as industrial robots and computer-aided design, and also general purpose devices like personal computers and mobile devices such as smartphones. The Internet is run on computers and it connects hundreds of millions of other computers and their users.
Early computers were only conceived as calculating devices. Since ancient times, simple manual devices like the abacus aided people in doing calculations. Early in the Industrial Revolution, some mechanical devices were built to automate long tedious tasks, such as guiding patterns for looms. More sophisticated electrical machines did specialized analog calculations in the early 20th century. The first digital electronic calculating machines were developed during World War II. The first semiconductor transistors in the late 1940s were followed by the silicon-based MOSFET (MOS transistor) and monolithic integrated circuit (IC) chip technologies in the late 1950s, leading to the microprocessor and the microcomputer revolution in the 1970s. The speed, power and versatility of computers have been increasing dramatically ever since then, with MOS transistor counts increasing at a rapid pace (as predicted by Moore's law), leading to the Digital Revolution during the late 20th to early 21st centuries.
Conventionally, a modern computer consists of at least one processing element, typically a central processing unit (CPU) in the form of a metal-oxide-semiconductor (MOS) microprocessor, along with some type of computer memory, typically MOS semiconductor memory chips. The processing element carries out arithmetic and logical operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices include input devices (keyboards, mice, joystick, etc.), output devices (monitor screens, printers, etc.), and input/output devices that perform both functions (e.g., the 2000s-era touchscreen). Peripheral devices allow information to be retrieved from an external source and they enable the result of operations to be saved and retrieved.
π Xenu, Leader of the Galactic Federation
Xenu (), also called Xemu, was, according to Scientology founder L. Ron Hubbard, the dictator of the "Galactic Confederacy" who brought billions of his people to Earth (then known as "Teegeeack") in DC-8-like spacecraft 75 million years ago, stacked them around volcanoes, and killed them with hydrogen bombs. Official Scientology scriptures hold that the thetans (immortal spirits) of these aliens adhere to humans, causing spiritual harm.
These events are known within Scientology as "Incident II", and the traumatic memories associated with them as "The Wall of Fire" or "R6 implant". The narrative of Xenu is part of Scientologist teachings about extraterrestrial civilizations and alien interventions in earthly events, collectively described as "space opera" by Hubbard. Hubbard detailed the story in Operating Thetan level III (OT III) in 1967, warning that the "R6 implant" (past trauma) was "calculated to kill (by pneumonia, etc.) anyone who attempts to solve it".
Within the Church of Scientology, the Xenu story is part of the church's secret "Advanced Technology", considered a sacred and esoteric teaching, which is normally only revealed to members who have completed a lengthy sequence of courses costing large amounts of money. The church avoids mention of Xenu in public statements and has gone to considerable effort to maintain the story's confidentiality, including legal action on the grounds of copyright and trade secrecy. Officials of the Church of Scientology widely deny or try to hide the Xenu story. Despite this, much material on Xenu has leaked to the public via court documents and copies of Hubbard's notes that have been distributed through the Internet. In commentary on the impact of the Xenu text, academic scholars have discussed and analyzed the writings by Hubbard and their place within Scientology within the contexts of science fiction, UFO religions, Gnosticism and creation myths.
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- "Xenu, Leader of the Galactic Federation" | 2020-12-08 | 11 Upvotes 4 Comments
π The Emu War
The Emu War, also known as the Great Emu War, was a nuisance wildlife management military operation undertaken in Australia over the latter part of 1932 to address public concern over the number of emus said to be running amok in the Campion district of Western Australia. The unsuccessful attempts to curb the population of emus, a large flightless bird indigenous to Australia, employed soldiers armed with Lewis gunsβleading the media to adopt the name "Emu War" when referring to the incident. While a number of the birds were killed, the emu population persisted and continued to cause crop destruction.
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- "The Emu War" | 2020-02-05 | 80 Upvotes 34 Comments