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🔗 Mathematics 🔗 Physics

Earnshaw's theorem states that a collection of point charges cannot be maintained in a stable stationary equilibrium configuration solely by the electrostatic interaction of the charges. This was first proven by British mathematician Samuel Earnshaw in 1842. It is usually referenced to magnetic fields, but was first applied to electrostatic fields.

Earnshaw's theorem applies to classical inverse-square law forces (electric and gravitational) and also to the magnetic forces of permanent magnets, if the magnets are hard (the magnets do not vary in strength with external fields). Earnshaw's theorem forbids magnetic levitation in many common situations.

If the materials are not hard, Braunbeck's extension shows that materials with relative magnetic permeability greater than one (paramagnetism) are further destabilising, but materials with a permeability less than one (diamagnetic materials) permit stable configurations.

🔗 Religion 🔗 Skepticism 🔗 Bible 🔗 Islam 🔗 Judaism 🔗 Iraq 🔗 Turkey 🔗 Mythology

Searches for Noah's Ark have been reported since antiquity, as ancient scholars sought to affirm the historicity of the Genesis flood narrative by citing accounts of relics recovered from the Ark.^: 43–47 With the emergence of biblical archaeology in the 19th century, the potential of a formal search attracted interest in alleged discoveries and hoaxes. By the 1940s, expeditions were being organized to follow up on these apparent leads.^: 8–9 This modern search movement has been informally called "arkeology".

In 2020, the young Earth creationist group the Institute for Creation Research acknowledged that, despite many expeditions, Noah's Ark had not been found and is unlikely to be found. Many of the supposed findings and methods used in the search are regarded as pseudoscience and pseudoarchaeology by geologists and archaeologists.^{: 581–582 : 72–75}

🔗 Songs

"Old Man Trump" is a song with lyrics written by American folk singer-songwriter Woody Guthrie in 1954. The song describes the racist housing practices and discriminatory rental policies of his landlord, Fred Trump (the father of the 45th president of the United States, Donald Trump). Although the lyrics were written in 1954, it was never recorded by Guthrie. In January 2016, Will Kaufman, a Guthrie scholar and professor of American literature and culture at the University of Central Lancashire, unearthed the handwritten lyrics while conducting research at the Woody Guthrie Archives in Tulsa, Oklahoma.

🔗 Lists 🔗 Food and drink 🔗 Plants

This is a list of vegetables which are grown or harvested primarily for the consumption of their leafy parts, either raw or cooked. Many plants with leaves that are consumed in small quantities as a spice such as oregano, for medicinal purposes such as lime, or used in infusions such as tea, are not included in this list.

🔗 Biography 🔗 Espionage 🔗 Military history 🔗 Military history/Military biography 🔗 Biography/military biography 🔗 Military history/Intelligence 🔗 United Kingdom 🔗 Military history/World War II 🔗 Military history/German military history 🔗 Military history/Spanish military history 🔗 Spain 🔗 Military history/European military history 🔗 Military history/British military history

Juan Pujol García (Spanish: [ˈxwan puˈʝol ɣaɾˈθi.a]; 14 February 1912 – 10 October 1988), also known as Joan Pujol i García (Catalan: [ʒuˈan puˈʒɔl i ɣəɾˈsi.ə]), was a Spanish spy who acted as a double agent loyal to Great Britain against Nazi Germany during World War II, when he relocated to Britain to carry out fictitious spying activities for the Germans. He was given the codename Garbo by the British; their German counterparts codenamed him Alaric and referred to his non-existent spy network as "Arabal".

After developing a loathing of political extremism of all sorts during the Spanish Civil War, Pujol decided to become a spy for Britain as a way to do something "for the good of humanity". Pujol and his wife contacted the British Embassy in Madrid, which rejected his offer.

Undeterred, he created a false identity as a fanatically pro-Nazi Spanish government official and successfully became a German agent. He was instructed to travel to Britain and recruit additional agents; instead he moved to Lisbon and created bogus reports about Britain from a variety of public sources, including a tourist guide to Britain, train timetables, cinema newsreels and magazine advertisements.

Although the information would not have withstood close examination, Pujol soon established himself as a trustworthy agent. He began inventing fictitious sub-agents who could be blamed for false information and mistakes. The Allies finally accepted Pujol when the Germans expended considerable resources attempting to hunt down a fictitious convoy. Following interviews by Desmond Bristow of Section V MI6 Iberian Section, Juan Pujol was taken on. The family were moved to Britain and Pujol was given the code name "Garbo". Pujol and his handler Tomás Harris spent the rest of the war expanding the fictitious network, communicating to the German handlers at first by letters and later by radio. Eventually the Germans were funding a network of 27 agents, all fictitious.

Pujol had a key role in the success of Operation Fortitude, the deception operation intended to mislead the Germans about the timing, location and scale of the invasion of Normandy in 1944. The false information Pujol supplied helped persuade the Germans that the main attack would be in the Pas de Calais, so that they kept large forces there before and even after the invasion. Pujol had the distinction of receiving military decorations from both sides of the war – being awarded the Iron Cross and becoming a Member of the Order of the British Empire.

🔗 Climate change 🔗 Environment 🔗 Volcanoes

The 1808 mystery eruption was a large volcanic eruption conjectured to have taken place in late 1808, possibly in the southwest Pacific. A VEI-6 eruption, comparable to the 1883 eruption of Krakatoa, is suspected of having contributed to a period of global cooling that lasted for years, analogous to how the 1815 eruption of Mount Tambora (VEI-7) led to the Year Without a Summer in 1816.

🔗 Military history 🔗 Military history/African military history 🔗 British Empire 🔗 Military history/Maritime warfare 🔗 African diaspora 🔗 Military history/European military history 🔗 Military history/British military history

The British Royal Navy established the West Africa Squadron at substantial expense in 1808 after Parliament passed the Slave Trade Act of 1807, an Act for the Abolition of the Slave Trade. The squadron's task was to suppress the Atlantic slave trade by patrolling the coast of West Africa. With a home base at Portsmouth, England, it began with two small ships, the 32-gun fifth-rate frigate HMS Solebay and the Cruizer-class brig-sloop HMS Derwent. At the height of its operations, the squadron employed a sixth of the Royal Navy fleet and marines. In 1819 the Royal Navy established a West Coast of Africa Station and the West Africa Squadron became known as the Preventative Squadron. It remained an independent command until 1856 and then again 1866 to 1867. Between 1830 and 1865, more than 1,500 British sailors died on their mission of freeing slaves with the West Africa Squadron.

Between 1808 and 1860 the West Africa Squadron captured 1,600 slave ships and freed 150,000 Africans. It is considered the most costly international moral action in modern history.

The Squadron has been described as being poorly resourced and plagued by corruption; it only managed to capture around 6% of the transatlantic slave ships, but patrolling 3,000 miles of African coast from 1808 to 1860 it liberated 150,000 Africans.

🔗 Biography 🔗 Iran 🔗 Biography/science and academia 🔗 Open Access

Amir Emad Mirmirani (Persian: امیرعماد میرمیرانی) known by the nickname Jadi, is a programmer, blogger and internet activist in the field of Free and open-source software and Linux in Iran. He was arrested in October 2022 during the Iranian protests following the death of Mahsa Amini.

🔗 Aviation 🔗 Physics 🔗 Aviation/aircraft

A vacuum airship, also known as a vacuum balloon, is a hypothetical airship that is evacuated rather than filled with a lighter-than-air gas such as hydrogen or helium. First proposed by Italian Jesuit priest Francesco Lana de Terzi in 1670, the vacuum balloon would be the ultimate expression of lifting power per volume displaced.

🔗 Philosophy 🔗 Philosophy/Ethics

The hedonic treadmill, also known as hedonic adaptation, is the observed tendency of humans to quickly return to a relatively stable level of happiness despite major positive or negative events or life changes. According to this theory, as a person makes more money, expectations and desires rise in tandem, which results in no permanent gain in happiness. Brickman and Donald T. Campbell coined the term in their essay "Hedonic Relativism and Planning the Good Society" (1971). The concept dates back centuries, to such writers as St. Augustine, cited in Robert Burton's 1621 Anatomy of Melancholy: "A true saying it is, Desire hath no rest, is infinite in itself, endless, and as one calls it, a perpetual rack, or horse-mill."

The hedonic (or happiness) set point has gained interest throughout the field of positive psychology where it has been developed and revised further. Given that hedonic adaptation generally demonstrates that a person's long-term happiness is not significantly affected by otherwise impacting events, positive psychology has concerned itself with the discovery of things that can lead to lasting changes in happiness levels.