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🔗 Astronomy 🔗 Central Asia 🔗 Museums 🔗 Central Asia/Uzbekistan

The Ulugh Beg Observatory is an observatory in Samarkand, Uzbekistan. Built in the 1420s by the Timurid astronomer Ulugh Beg. Islamic astronomers who worked at the observatory include Al-Kashi, Ali Qushji, and Ulugh Beg himself. The observatory was destroyed in 1449 and rediscovered in 1908.

🔗 Physics 🔗 Astronomy 🔗 Physics/relativity 🔗 Astronomy/Astronomical objects

In general relativity, a white hole is a hypothetical region of spacetime and singularity that cannot be entered from the outside, although energy-matter, light and information can escape from it. In this sense, it is the reverse of a black hole, which can be entered only from the outside and from which energy-matter, light and information cannot escape. White holes appear in the theory of eternal black holes. In addition to a black hole region in the future, such a solution of the Einstein field equations has a white hole region in its past. This region does not exist for black holes that have formed through gravitational collapse, however, nor are there any observed physical processes through which a white hole could be formed.

Supermassive black holes (SBHs) are theoretically predicted to be at the center of every galaxy and that possibly, a galaxy cannot form without one. Stephen Hawking and others have proposed that these SBHs spawn a supermassive white hole/Big Bang.

🔗 Switzerland

🔗 Board and table games

18XX is the generic term for a series of board games that, with a few exceptions, recreate the building of railroad corporations during the 19th century; individual games within the series use particular years in the 19th century as their title (usually the date of the start of railway development in the area of the world they cover), or "18" plus a two or more letter geographical designator (such as 18EU for a game set in the European Union). The games 2038, set in the future, and Poseidon and Ur, 1830 BC, both set in ancient history, are also regarded as 18XX titles as their game mechanics and titling nomenclature are similar despite variance from the common railroad/stock-market theme.

The 18XX series has its origins in the game 1829, first produced by Francis Tresham in the mid-1970s. 1829 was chosen as it was the year of the Rainhill Trials. 1830 was produced by Avalon Hill in 1986, and was the first game of the series widely available in the United States; it is seen as the basic 18XX game by the U.S. audience.

In addition to traditionally published games, the 18XX series has spawned self-published variants and games published by low-volume game companies.

With few exceptions (such as 2038), 18XX titles are multiplayer board games without random variables in their game mechanics.

🔗 Biography 🔗 Canada 🔗 Athletics 🔗 Running 🔗 Biography/sports and games

Terrance Stanley Fox (July 28, 1958 – June 28, 1981) was a Canadian athlete, humanitarian, and cancer research activist. In 1980, with one leg having been amputated due to cancer, he embarked on an east to west cross-Canada run to raise money and awareness for cancer research. Although the spread of his cancer eventually forced him to end his quest after 143 days and 5,373 kilometres (3,339 mi), and ultimately cost him his life, his efforts resulted in a lasting, worldwide legacy. The annual Terry Fox Run, first held in 1981, has grown to involve millions of participants in over 60 countries and is now the world's largest one-day fundraiser for cancer research; over C$750 million has been raised in his name, as of January 2018.

Fox was a distance runner and basketball player for his Port Coquitlam high school, now named after him, and Simon Fraser University. His right leg was amputated in 1977 after he was diagnosed with osteosarcoma, though he continued to run using an artificial leg. He also played wheelchair basketball in Vancouver, winning three national championships.

In 1980, he began the Marathon of Hope, a cross-country run to raise money for cancer research. He hoped to raise one dollar from each of Canada's 24 million people. He began with little fanfare from St John's, Newfoundland and Labrador, in April and ran the equivalent of a full marathon every day. Fox had become a national star by the time he reached Ontario; he made numerous public appearances with businessmen, athletes, and politicians in his efforts to raise money. He was forced to end his run outside Thunder Bay when the cancer spread to his lungs. His hopes of overcoming the disease and completing his marathon ended when he died nine months later.

In addition to being the youngest person ever named a Companion of the Order of Canada, Fox won the 1980 Lou Marsh Award as the nation's top sportsman and was named Canada's Newsmaker of the Year in both 1980 and 1981. Considered a national hero, he has had many buildings, statues, roads, and parks named in his honour across the country.

🔗 History 🔗 Military history 🔗 Military history/Early Modern warfare 🔗 European history

The "General Crisis" is the term used by some historians to describe the period of widespread conflict and instability that occurred from the early 17th century to the early 18th century in Europe and in more recent historiography in the world at large. The concept is much debated by historians; there is no consensus.

The term was coined by Eric Hobsbawm in his pair of 1954 articles entitled "The Crisis of the Seventeenth Century" published in Past and Present.

🔗 Philosophy 🔗 Philosophy/Philosophical literature 🔗 Politics 🔗 Philosophy/Ancient philosophy 🔗 Philosophy/Ethics

The Nicomachean Ethics (; Ancient Greek: Ἠθικὰ Νικομάχεια, Ēthika Nikomacheia) is the name normally given to Aristotle's best-known work on ethics. The work, which plays a pre-eminent role in defining Aristotelian ethics, consists of ten books, originally separate scrolls, and is understood to be based on notes from his lectures at the Lyceum. The title is often assumed to refer to his son Nicomachus, to whom the work was dedicated or who may have edited it (although his young age makes this less likely). Alternatively, the work may have been dedicated to his father, who was also called Nicomachus.

The theme of the work is a Socratic question previously explored in the works of Plato, Aristotle's friend and teacher, of how men should best live. In his Metaphysics, Aristotle described how Socrates, the friend and teacher of Plato, had turned philosophy to human questions, whereas pre-Socratic philosophy had only been theoretical. Ethics, as now separated out for discussion by Aristotle, is practical rather than theoretical, in the original Aristotelian senses of these terms. In other words, it is not only a contemplation about good living, because it also aims to create good living. It is therefore connected to Aristotle's other practical work, the Politics, which similarly aims at people becoming good. Ethics is about how individuals should best live, while the study of politics is from the perspective of a law-giver, looking at the good of a whole community.

The Nicomachean Ethics is widely considered one of the most important historical philosophical works, and had an important impact upon the European Middle Ages, becoming one of the core works of medieval philosophy. It therefore indirectly became critical in the development of all modern philosophy as well as European law and theology. Many parts of the Nicomachean Ethics are well known in their own right, within different fields. In the Middle Ages, a synthesis between Aristotelian ethics and Christian theology became widespread, in Europe as introduced by Albertus Magnus. While various philosophers had influenced Christendom since its earliest times, in Western Europe Aristotle became "the Philosopher". The most important version of this synthesis was that of Thomas Aquinas. Other more "Averroist" Aristotelians such as Marsilius of Padua were controversial but also influential. (Marsilius is for example sometimes said to have influenced the controversial English political reformer Thomas Cromwell.)

A critical period in the history of this work's influence is at the end of the Middle Ages, and beginning of modernity, when several authors such as Francis Bacon and Thomas Hobbes, argued forcefully and largely successfully that the medieval Aristotelian tradition in practical thinking had become a great impediment to philosophy in their time. However, in more recent generations, Aristotle's original works (if not those of his medieval followers) have once again become an important source. More recent authors influenced by this work include Alasdair MacIntyre, G. E. M. Anscombe, Hans-Georg Gadamer, Martha Nussbaum and Avital Ronell.

🔗 Computing 🔗 Computing/Computer Security 🔗 Computing/Networking

In computer networking, port knocking is a method of externally opening ports on a firewall by generating a connection attempt on a set of prespecified closed ports. Once a correct sequence of connection attempts is received, the firewall rules are dynamically modified to allow the host which sent the connection attempts to connect over specific port(s). A variant called single packet authorization (SPA) exists, where only a single "knock" is needed, consisting of an encrypted packet.

The primary purpose of port knocking is to prevent an attacker from scanning a system for potentially exploitable services by doing a port scan, because unless the attacker sends the correct knock sequence, the protected ports will appear closed.

🔗 Australia 🔗 Australia/Western Australia 🔗 Australia/Australian biota 🔗 Spiders

Number 16 (c. 1974 – 2016), also known as #16, was a wild female trapdoor spider (Gaius villosus, family Idiopidae) that lived in North Bungulla Reserve near Tammin, Western Australia. She lived an estimated 43 years and became the longest-lived spider on record, beating a 28-year-old tarantula who previously held the title. When Number 16 finally died in 2016, it was not of old age but from a parasitic wasp sting.