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🔗 Linguistics 🔗 Linguistics/Etymology

This is a list of etymologies proposed for the word OK or okay. The majority can be easily classified as false etymologies, or possibly folk etymologies. H. L. Mencken, in The American Language, lists serious candidates and "a few of the more picturesque or preposterous". Allen Walker Read surveyed a variety of explanations in a 1964 article titled The Folklore of "O. K." Eric Partridge described O.K. as "an evergreen of the correspondence column."

🔗 Novels 🔗 Novels/Science fiction 🔗 Science Fiction 🔗 Solar System/Mars 🔗 Solar System

The Mars trilogy is a series of science fiction novels by Kim Stanley Robinson that chronicles the settlement and terraforming of the planet Mars through the personal and detailed viewpoints of a wide variety of characters spanning almost two centuries. Ultimately more utopian than dystopian, the story focuses on egalitarian, sociological, and scientific advances made on Mars, while Earth suffers from overpopulation and ecological disaster.

The three novels are Red Mars (1992), Green Mars (1993), and Blue Mars (1996). The Martians (1999) is a collection of short stories set in the same fictional universe. Red Mars won the BSFA Award in 1992 and Nebula Award for Best Novel in 1993. Green Mars won the Hugo Award for Best Novel and Locus Award for Best Science Fiction Novel in 1994. Blue Mars also won the Hugo and Locus Awards in 1997.

Icehenge (1984), Robinson's first novel about Mars, is not set in this universe but deals with similar themes and plot elements. The trilogy shares some similarities with Robinson's more recent novel 2312 (2012); for instance, the terraforming of Mars and the extreme longevity of the characters in both novels.

🔗 Internet 🔗 Law 🔗 Freedom of speech 🔗 Google

Google and its subsidiary companies, such as YouTube, have removed or omitted information from its services to comply with its company policies, legal demands, and government censorship laws. Google's censorship varies between countries and their regulations, and ranges from advertisements to speeches. Over the years, the search engine's censorship policies and targets have also differed, and have been the source of internet censorship debates.

Numerous governments have asked Google to censor what they publish. In 2012, Google ruled in favor of more than half of the requests they received via court orders and phone calls. This did not include China and Iran who had blocked their site entirely.

🔗 Economics 🔗 Literature 🔗 Astronomy

The Theory of Interstellar Trade is a paper written in 1978 by the economist Paul Krugman. The paper was first published in March 2010 in the journal Economic Inquiry. He described the paper as something he wrote to cheer himself up when he was an "oppressed assistant professor" caught up in the academic rat race.

Krugman analyzed the question of

How should interest rates on goods in transit be computed when the goods travel at close to the speed of light? This is a problem because the time taken in transit will appear less to an observer traveling with the goods than to a stationary observer.

Krugman emphasized that in spite of its farcical subject matter, the economic analysis in the paper is correctly done. In his own words,

while the subject of this paper is silly, the analysis actually does make sense. This paper, then, is a serious analysis of a ridiculous subject, which is of course the opposite of what is usual in economics.

🔗 Physics 🔗 Systems 🔗 Systems/Chaos theory

In condensed matter physics, Hofstadter's butterfly describes the spectral properties of non-interacting two dimensional electrons in a magnetic field. The fractal, self-similar, nature of the spectrum was discovered in the 1976 Ph.D. work of Douglas Hofstadter and is one of the early examples of computer graphics. The name reflects the visual resemblance of the figure on the right to a swarm of butterflies flying to infinity.

The Hofstadter butterfly plays an important role in the theory of the integer quantum Hall effect, and D.J. Thouless has been awarded the Nobel prize in physics in 2016 for the discovery that the wings of the butterfly are characterized by Chern integers, the quantized Hall conductances discovered in 1980 by Klaus von Klitzing for which he has been awarded the Nobel prize in 1985. The colors in the diagram reflect the different Chern numbers.

🔗 Technology

Tensegrity, tensional integrity or floating compression is a structural principle based on a system of isolated components under compression inside a network of continuous tension, and arranged in such a way that the compressed members (usually bars or struts) do not touch each other while the prestressed tensioned members (usually cables or tendons) delineate the system spatially.

The term was coined by Buckminster Fuller in the 1960s as a portmanteau of "tensional integrity". The other denomination of tensegrity, floating compression, was used mainly by the constructivist artist Kenneth Snelson.

🔗 Economics 🔗 Energy 🔗 Globalization

Petrodollar recycling is the international spending or investment of a country's revenues from petroleum exports ("petrodollars"). It generally refers to the phenomenon of major petroleum-exporting nations, mainly the OPEC members plus Russia and Norway, earning more money from the export of crude oil than they could efficiently invest in their own economies. The resulting global interdependencies and financial flows, from oil producers back to oil consumers, can reach a scale of hundreds of billions of US dollars per year – including a wide range of transactions in a variety of currencies, some pegged to the US dollar and some not. These flows are heavily influenced by government-level decisions regarding international investment and aid, with important consequences for both global finance and petroleum politics. The phenomenon is most pronounced during periods when the price of oil is historically high.

The term petrodollar was coined in the early 1970s during the oil crisis, and the first major petrodollar surge (1974–1981) resulted in more financial complications than the second (2005–2014).

In August 2018, Venezuela declared that it would price its oil in Euros, Yuan and other currencies.

🔗 Cryptography 🔗 Cryptography/Computer science

In cryptography, the socialist millionaire problem is one in which two millionaires want to determine if their wealth is equal without disclosing any information about their riches to each other. It is a variant of the Millionaire's Problem whereby two millionaires wish to compare their riches to determine who has the most wealth without disclosing any information about their riches to each other.

It is often used as a cryptographic protocol that allows two parties to verify the identity of the remote party through the use of a shared secret, avoiding a man-in-the-middle attack without the inconvenience of manually comparing public key fingerprints through an outside channel. In effect, a relatively weak password/passphrase in natural language can be used.

🔗 Science

In combinatorial mathematics, an Aztec diamond of order n consists of all squares of a square lattice whose centers (x,y) satisfy |x| + |y| ≤ n. Here n is a fixed integer, and the square lattice consists of unit squares with the origin as a vertex of 4 of them, so that both x and y are half-integers.

The Aztec diamond theorem states that the number of domino tilings of the Aztec diamond of order n is 2^n(n+1)/2. The Arctic Circle theorem says that a random tiling of a large Aztec diamond tends to be frozen outside a certain circle.

It is common to color the tiles in the following fashion. First consider a checkerboard coloring of the diamond. Each tile will cover exactly one black square. Vertical tiles where the top square covers a black square, is colored in one color, and the other vertical tiles in a second. Similarly for horizontal tiles.

Knuth has also defined Aztec diamonds of order n + 1/2. They are identical with the polyominoes associated with the centered square numbers.

🔗 Mathematics

In number theory, Mills' constant is defined as the smallest positive real number A such that the floor function of the double exponential function

${\displaystyle \lfloor A^{3^{n}}\rfloor }$

is a prime number, for all natural numbers n. This constant is named after William H. Mills who proved in 1947 the existence of A based on results of Guido Hoheisel and Albert Ingham on the prime gaps. Its value is unknown, but if the Riemann hypothesis is true, it is approximately 1.3063778838630806904686144926... (sequence A051021 in the OEIS).