Have a deep view into what people are curious about.

🔗 Telecommunications 🔗 Brands

The IBM Simon Personal Communicator (simply known as IBM Simon) is a handheld, touchscreen PDA designed by International Business Machines (IBM), and manufactured by Mitsubishi Electric. BellSouth Cellular Corp. distributed the Simon Personal Communicator in the United States between August 1994 and February 1995, selling 50,000 units. The Simon Personal Communicator was the first personal digital assistant or PDA to include telephony features. The battery lasted only an hour, and flip phones became increasingly slim which led to its demise.

🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Judaism

Atbash (Hebrew: אתבש‎; also transliterated Atbaš) is a monoalphabetic substitution cipher originally used to encrypt the Hebrew alphabet. It can be modified for use with any known writing system with a standard collating order.

🔗 United States 🔗 Death 🔗 Agriculture 🔗 Death/Suicide

Farmers' suicides in the United States refers to the instances of American farmers taking their own lives, largely since the 1980s, partly due to their falling into debt, but as a larger mental-health crisis among U.S. agriculture workers. In the Midwest alone, over 1,500 farmers have taken their own lives since the 1980s. It mirrors a crisis happening globally: in Australia, a farmer dies by suicide every four days; in the United Kingdom, one farmer a week takes their own life, in France it is one every two days. More than 270,000 farmers have died by suicide since 1995 in India.

Farmers are among the most likely to die by suicide, in comparison to other occupations, according to a study published in January 2020 by the Centers for Disease Control and Prevention (CDC). Researchers at the University of Iowa found that farmers, and others in the agricultural trade, had the highest suicide rate of all occupations from 1992 to 2010, the years covered in a 2017 study. The rate was 3.5 times that of the general population. This echoed a study conducted the previous year by the CDC and another undertaken by the National Rural Health Association (NRHA).

Most family farmers seem to agree on what led to their plight: government policy. In the years after the New Deal, they say, the United States set a price floor for farmers, essentially ensuring they received a minimum wage for the crops they produced. But the government began rolling back this policy in the 1970s, and now the global market largely determines the price they get for their crops. Big farms can make do with lower prices for crops by increasing their scale; a few cents per gallon of cow's milk adds up if you have thousands of cows.

—Time, November 27, 2019

As of April 2023, the suicide rate within the farming community exceeds that of the general population by three and a half times.

🔗 Physics

The quantum Zeno effect (also known as the Turing paradox) is a feature of quantum-mechanical systems allowing a particle's time evolution to be slowed down by measuring it frequently enough with respect to some chosen measurement setting.

Sometimes this effect is interpreted as "a system cannot change while you are watching it". One can "freeze" the evolution of the system by measuring it frequently enough in its known initial state. The meaning of the term has since expanded, leading to a more technical definition, in which time evolution can be suppressed not only by measurement: the quantum Zeno effect is the suppression of unitary time evolution in quantum systems provided by a variety of sources: measurement, interactions with the environment, stochastic fields, among other factors. As an outgrowth of study of the quantum Zeno effect, it has become clear that applying a series of sufficiently strong and fast pulses with appropriate symmetry can also decouple a system from its decohering environment.

The name comes from Zeno's arrow paradox, which states that because an arrow in flight is not seen to move during any single instant, it cannot possibly be moving at all. The first rigorous and general derivation of the quantum Zeno effect was presented in 1974 by Degasperis, Fonda, and Ghirardi, although it had previously been described by Alan Turing. The comparison with Zeno's paradox is due to a 1977 article by George Sudarshan and Baidyanath Misra.

According to the reduction postulate, each measurement causes the wavefunction to collapse to an eigenstate of the measurement basis. In the context of this effect, an observation can simply be the absorption of a particle, without the need of an observer in any conventional sense. However, there is controversy over the interpretation of the effect, sometimes referred to as the "measurement problem" in traversing the interface between microscopic and macroscopic objects.

Another crucial problem related to the effect is strictly connected to the time–energy indeterminacy relation (part of the indeterminacy principle). If one wants to make the measurement process more and more frequent, one has to correspondingly decrease the time duration of the measurement itself. But the request that the measurement last only a very short time implies that the energy spread of the state in which reduction occurs becomes increasingly large. However, the deviations from the exponential decay law for small times is crucially related to the inverse of the energy spread, so that the region in which the deviations are appreciable shrinks when one makes the measurement process duration shorter and shorter. An explicit evaluation of these two competing requests shows that it is inappropriate, without taking into account this basic fact, to deal with the actual occurrence and emergence of Zeno's effect.

Closely related (and sometimes not distinguished from the quantum Zeno effect) is the watchdog effect, in which the time evolution of a system is affected by its continuous coupling to the environment.

🔗 Europe/ESA

🔗 Mathematics

The Erdős number (Hungarian: [ˈɛrdøːʃ]) describes the "collaborative distance" between mathematician Paul Erdős and another person, as measured by authorship of mathematical papers. The same principle has been applied in other fields where a particular individual has collaborated with a large and broad number of peers.

🔗 United States History 🔗 Past Political Scandals and Controversies

The Burr conspiracy was a suspected treasonous cabal of US planters, politicians, and army officers in the early 19th century. The alleged cabal was led by Aaron Burr, the former Vice President of the United States (1801–1805). According to the accusations against him, his goal was to create an independent country in the center of North America including the Southwestern United States and parts of Mexico. Burr's version was that he intended to farm 40,000 acres (160 km²) in the Texas Territory which had been leased to him by the Spanish Crown.

President Thomas Jefferson ordered Burr arrested and indicted for treason, despite a lack of firm evidence. Burr's true intentions remain unclear to historians; some claim that he intended to take parts of Texas and the Louisiana Purchase for himself, others, that he intended to conquer Mexico, and yet others, that he planned to conquer most of the North American continent. The number of men backing him is also unclear, with accounts varying from fewer than forty to over seven thousand. He was acquitted of treason, but the trial destroyed his already faltering political career.

🔗 Computing

In computer programming, homoiconicity (from the Greek words homo- meaning "the same" and icon meaning "representation") is a property of some programming languages. A language is homoiconic if a program written in it can be manipulated as data using the language, and thus the program's internal representation can be inferred just by reading the program itself. For example, a Lisp program is written as a regular Lisp list, and can be manipulated by other Lisp code. In homoiconic languages, all code can be accessed and transformed as data, using the same representation. This property is often summarized by saying that the language treats "code as data".

In a homoiconic language, the primary representation of programs is also a data structure in a primitive type of the language itself. This makes metaprogramming easier than in a language without this property: reflection in the language (examining the program's entities at runtime) depends on a single, homogeneous structure, and it does not have to handle several different structures that would appear in a complex syntax.

As noted above, a commonly cited example is Lisp, which was created to allow for easy list manipulations and where the structure is given by S-expressions that take the form of nested lists. Lisp programs are written in the form of lists; the result is that the program can access its own functions and procedures while running, and programmatically alter itself on the fly. Homoiconic languages typically include full support of syntactic macros, allowing the programmer to express transformations of programs in a concise way. Examples are the programming languages Clojure (a contemporary dialect of Lisp), Rebol (also its successor Red), Refal, Prolog, and more recently Julia.

🔗 Cryptography 🔗 Cryptography/Computer science

Shamir's Secret Sharing is an algorithm in cryptography created by Adi Shamir. It is a form of secret sharing, where a secret is divided into parts, giving each participant its own unique part.

To reconstruct the original secret, a minimum number of parts is required. In the threshold scheme this number is less than the total number of parts. Otherwise all participants are needed to reconstruct the original secret.

🔗 Games

Nim is a mathematical game of strategy in which two players take turns removing (or "nimming") objects from distinct heaps or piles. On each turn, a player must remove at least one object, and may remove any number of objects provided they all come from the same heap or pile. Depending on the version being played, the goal of the game is either to avoid taking the last object, or to take the last object.

Variants of Nim have been played since ancient times. The game is said to have originated in China—it closely resembles the Chinese game of 捡石子 jiǎn-shízi, or "picking stones"—but the origin is uncertain; the earliest European references to Nim are from the beginning of the 16th century. Its current name was coined by Charles L. Bouton of Harvard University, who also developed the complete theory of the game in 1901, but the origins of the name were never fully explained.

Nim is typically played as a misère game, in which the player to take the last object loses. Nim can also be played as a normal play game, where the player taking the last object wins. This is called normal play because the last move is a winning move in most games, even though it is not the normal way that Nim is played. In either normal play or a misère game, when the number of heaps with at least two objects is exactly equal to one, the next player who takes next can easily win. If this removes either all or all but one objects from the heap that has two or more, then no heaps will have more than one object, so the players are forced to alternate removing exactly one object until the game ends. If the player leaves an even number of non-zero heaps (as the player would do in normal play), the player takes last; if the player leaves an odd number of heaps (as the player would do in misère play), then the other player takes last.

Normal play Nim (or more precisely the system of nimbers) is fundamental to the Sprague–Grundy theorem, which essentially says that in normal play every impartial game is equivalent to a Nim heap that yields the same outcome when played in parallel with other normal play impartial games (see disjunctive sum).

While all normal play impartial games can be assigned a Nim value, that is not the case under the misère convention. Only tame games can be played using the same strategy as misère Nim.

Nim is a special case of a poset game where the poset consists of disjoint chains (the heaps).

The evolution graph of the game of Nim with three heaps is the same as three branches of the evolution graph of the Ulam-Warburton automaton.

At the 1940 New York World's Fair Westinghouse displayed a machine, the Nimatron, that played Nim. From May 11, 1940 to October 27, 1940 only a few people were able to beat the machine in that six week period; if they did they were presented with a coin that said Nim Champ. It was also one of the first ever electronic computerized games. Ferranti built a Nim playing computer which was displayed at the Festival of Britain in 1951. In 1952 Herbert Koppel, Eugene Grant and Howard Bailer, engineers from the W. L. Maxon Corporation, developed a machine weighing 23 kilograms (50 lb) which played Nim against a human opponent and regularly won. A Nim Playing Machine has been described made from TinkerToy.

The game of Nim was the subject of Martin Gardner's February 1958 Mathematical Games column in Scientific American. A version of Nim is played—and has symbolic importance—in the French New Wave film Last Year at Marienbad (1961).