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🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Chemistry

Terfenol-D, an alloy of the formula Tb_xDy_1−xFe₂ (x ≈ 0.3), is a magnetostrictive material. It was initially developed in the 1970s by the Naval Ordnance Laboratory in United States. The technology for manufacturing the material efficiently was developed in the 1980s at Ames Laboratory under a U.S. Navy-funded program. It is named after terbium, iron (Fe), Naval Ordnance Laboratory (NOL), and the D comes from dysprosium.

🔗 Soviet Union 🔗 Military history 🔗 Military history/Cold War 🔗 Cold War 🔗 Military history/Russian, Soviet and CIS military history

On 26 September 1983, the nuclear early-warning radar of the Soviet Union reported the launch of one intercontinental ballistic missile with four more missiles behind it, from bases in the United States. These missile attack warnings were suspected to be false alarms by Stanislav Petrov, an officer of the Soviet Air Defence Forces on duty at the command center of the early-warning system. He decided to wait for corroborating evidence—of which none arrived—rather than immediately relaying the warning up the chain-of-command. This decision is seen as having prevented a retaliatory nuclear attack against the United States and its NATO allies, which would likely have resulted in an escalation to a full-scale nuclear war. Investigation of the satellite warning system later determined that the system had indeed malfunctioned.

🔗 Geography 🔗 Romania 🔗 Ecology 🔗 Caves

Movile Cave (Romanian: Peștera Movile) is a cave near Mangalia, Constanța County, Romania discovered in 1986 by Cristian Lascu a few kilometers from the Black Sea coast. It is notable for its unique groundwater ecosystem abundant in hydrogen sulfide and carbon dioxide, but low in oxygen. Life in the cave has been separated from the outside for the past 5.5 million years and it is based completely on chemosynthesis rather than photosynthesis.

The thermal grill illusion is a sensory illusion originally demonstrated in 1896 by the Swedish physician Torsten Thunberg. The illusion is created by an interlaced grill of warm (e.g., 40°C/104°F) and cool (20°C/68°F) bars. When someone presses a hand against the grill, they experience the illusion of burning heat. But if the person presses against only a cool bar, only coolness is experienced; if the person presses against only a warm bar, only warmth is experienced.

Researchers have used the illusion to demonstrate that burning pain sensation is in fact a mixture of both cold and heat pain and that it is only the inhibition of the cold pain "channel" that reveals the heat component.

The illusion is demonstrated by positioning the middle finger in cold water and the ring and index fingers in warm water. Due to shortcomings in the body map - multisensory representation of the body - and this particular sensory input configuration, the brain is tricked into thinking the middle finger is in the warm water and the index and ring fingers in cold water.

In an fMRI experiment of the illusion, researchers recently observed an activation of the thalamus not seen for control stimuli. Also, activity in a portion of the right mid/anterior insula correlated with the perceived unpleasantness of the illusion.

🔗 Geology

Ruin marble is a kind of limestone or marble that contains light and dark patterns. It can give the impression of a ruined city scape.

It originates mostly from the city of Florence in the commune of Tuscany, in Central Italy. Its color pattern consists mainly of gray, brown and reddish, sometimes also blue and black, giving it the impression of a ruined landscape painting. The patterns (similar to Liesegang rings) develop during diagenesis due to periodic rhythmic precipitation of iron and manganese hydroxides from oxidizing aqueous fluids restricted laterally by calcite and clay filled joints.

🔗 Computing

Secure Scuttlebutt (SSB) is a peer-to peer communication protocol, mesh network, and self-hosted social media ecosystem. Each user hosts their own content and the content of the peers they follow, which provides fault tolerance and eventual consistency. Messages are digitally signed and added to an append-only list of messages published by an author. SSB is primarily used for implementing distributed social networks, and utilizes cryptography to assure that content remains unforged as it is propagated through the network.

🔗 Mathematics

Actuarial notation is a shorthand method to allow actuaries to record mathematical formulas that deal with interest rates and life tables.

Traditional notation uses a halo system where symbols are placed as superscript or subscript before or after the main letter. Example notation using the halo system can be seen below.

Various proposals have been made to adopt a linear system where all the notation would be on a single line without the use of superscripts or subscripts. Such a method would be useful for computing where representation of the halo system can be extremely difficult. However, a standard linear system has yet to emerge.

🔗 Philosophy 🔗 Philosophy/Logic

The nirvana fallacy is the informal fallacy of comparing actual things with unrealistic, idealized alternatives. It can also refer to the tendency to assume there is a perfect solution to a particular problem. A closely related concept is the "perfect solution fallacy."

By creating a false dichotomy that presents one option which is obviously advantageous—while at the same time being completely implausible—a person using the nirvana fallacy can attack any opposing idea because it is imperfect. Under this fallacy, the choice is not between real world solutions; it is, rather, a choice between one realistic achievable possibility and another unrealistic solution that could in some way be "better".

🔗 Soviet Union 🔗 Russia 🔗 Disaster management 🔗 Skepticism 🔗 Astronomy 🔗 Russia/science and education in Russia 🔗 Geology 🔗 Russia/physical geography of Russia 🔗 Russia/history of Russia 🔗 Paranormal

The Tunguska event was a massive ~12 megaton explosion that occurred near the Podkamennaya Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, on the morning of June 30, 1908. The explosion over the sparsely populated Eastern Siberian Taiga flattened an estimated 80 million trees over an area of 2,150 km² (830 sq mi) of forest, and eyewitness reports suggest that at least three people may have died in the event. The explosion is generally attributed to the air burst of a stony meteoroid about 50–60 metres (160–200 feet) in size.^{: p. 178} The meteoroid approached from the east-southeast, and likely with a relatively high speed of about 27 km/s. It is classified as an impact event, even though no impact crater has been found; the object is thought to have disintegrated at an altitude of 5 to 10 kilometres (3 to 6 miles) rather than to have hit the surface of the Earth.

The Tunguska event is the largest impact event on Earth in recorded history, though much larger impacts have occurred in prehistoric times. An explosion of this magnitude would be capable of destroying a large metropolitan area. It has been mentioned numerous times in popular culture, and has also inspired real-world discussion of asteroid impact avoidance.

🔗 United States 🔗 Biography 🔗 California 🔗 Aviation 🔗 Spaceflight 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Biography/science and academia 🔗 Military history/Military biography 🔗 Biography/military biography 🔗 LGBT studies 🔗 Aviation/aerospace biography 🔗 Chemistry 🔗 Military history/World War II 🔗 Military history/Cold War 🔗 Libertarianism 🔗 California/Southern California 🔗 California/Los Angeles area 🔗 Thelema 🔗 Occult

John Whiteside Parsons (born Marvel Whiteside Parsons; October 2, 1914 – June 17, 1952) was an American rocket engineer, chemist, and Thelemite occultist. Associated with the California Institute of Technology (Caltech), Parsons was one of the principal founders of both the Jet Propulsion Laboratory (JPL) and the Aerojet Engineering Corporation. He invented the first rocket engine to use a castable, composite rocket propellant, and pioneered the advancement of both liquid-fuel and solid-fuel rockets.

Born in Los Angeles, Parsons was raised by a wealthy family on Orange Grove Boulevard in Pasadena. Inspired by science fiction literature, he developed an interest in rocketry in his childhood and in 1928 began amateur rocket experiments with school friend Edward S. Forman. He dropped out of Pasadena Junior College and Stanford University due to financial difficulties during the Great Depression, and in 1934 he united with Forman and graduate Frank Malina to form the Caltech-affiliated Guggenheim Aeronautical Laboratory (GALCIT) Rocket Research Group, supported by GALCIT chairman Theodore von Kármán. In 1939 the GALCIT Group gained funding from the National Academy of Sciences (NAS) to work on Jet-Assisted Take Off (JATO) for the U.S. military. After the U.S. entered World War II, they founded Aerojet in 1942 to develop and sell JATO technology; the GALCIT Group became JPL in 1943.

Following some brief involvement with Marxism in 1939, Parsons converted to Thelema, the new religious movement founded by the English occultist Aleister Crowley. Together with his first wife, Helen Northrup, Parsons joined the Agape Lodge, the Californian branch of the Thelemite Ordo Templi Orientis (O.T.O.) in 1941. At Crowley's bidding, Parsons replaced Wilfred Talbot Smith as its leader in 1942 and ran the Lodge from his mansion on Orange Grove Boulevard. Parsons was expelled from JPL and Aerojet in 1944 owing to the Lodge's infamous reputation and to his hazardous workplace conduct.

In 1945, Parsons separated from Helen, after having an affair with her sister Sara; when Sara left him for L. Ron Hubbard, Parsons conducted the Babalon Working, a series of rituals intended to invoke the Thelemic goddess Babalon on Earth. He and Hubbard continued the working with Marjorie Cameron, whom Parsons married in 1946. After Hubbard and Sara defrauded him of his life savings, Parsons resigned from the O.T.O., then held various jobs while acting as a consultant for Israel's rocket program. Amid McCarthyism, Parsons was accused of espionage and left unable to work in rocketry. In 1952 Parsons died at the age of 37 in a home laboratory explosion that attracted national media attention; the police ruled it an accident, but many associates suspected suicide or murder.

Parsons's libertarian and occult writings were published posthumously. Historians of Western esoteric tradition cite him as one of the more prominent figures in propagating Thelema across North America. Although academic interest in his scientific career was negligible, historians have come to recognize Parsons's contributions to rocket engineering. For these innovations, his advocacy of space exploration and human spaceflight, and his role in founding JPL and Aerojet, Parsons is regarded as among the most important figures in the history of the U.S. space program. He has been the subject of several biographies and fictionalized portrayals.