Have a deep view into what people are curious about.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Classical Greece and Rome 🔗 Military history/Classical warfare

Polybolos, meaning "multi thrower" in Greek, was an ancient Greek repeating ballista reputedly invented by Dionysius of Alexandria, a 3rd-century BC Greek engineer at the Rhodes arsenal, and used in antiquity.

Philo of Byzantium encountered and described a weapon similar to the polybolos, a catapult that like a modern machine gun could fire again and again without a need to reload. Philo left a detailed description of the gears that powered its chain drive, the oldest known application of such a mechanism, and that placed bolt after bolt into its firing slot.

🔗 Military history/Early Muslim military history 🔗 Games

The two envelopes problem, also known as the exchange paradox, is a brain teaser, puzzle, or paradox in logic, probability, and recreational mathematics. It is of special interest in decision theory, and for the Bayesian interpretation of probability theory. Historically, it arose as a variant of the necktie paradox. The problem typically is introduced by formulating a hypothetical challenge of the following type:

It seems obvious that there is no point in switching envelopes as the situation is symmetric. However, because you stand to gain twice as much money if you switch while risking only a loss of half of what you currently have, it is possible to argue that it is more beneficial to switch. The problem is to show what is wrong with this argument.

🔗 Geography 🔗 Antarctica 🔗 Glaciers

A blue iceberg is visible after the ice from above the water melts, causing the smooth portion of ice from below the water to overturn. The rare blue ice is formed from the compression of pure snow, which then develops into glacial ice.

Icebergs may also appear blue due to light refraction and age. Older icebergs reveal vivid hues of green and blue, resulting from a high concentration of color, microorganisms, and compacted ice. One of the better known blue icebergs rests in the waters off Sermilik fjord near Greenland. It is described as an electric blue iceberg and is known to locals as "blue diamond".

🔗 Anthropology 🔗 Athletics 🔗 Running 🔗 Evolutionary biology

The endurance running hypothesis is the hypothesis that the evolution of certain human characteristics can be explained as adaptations to long-distance running. The hypothesis suggests that endurance running played an important role for early hominins in obtaining food. Researchers have proposed that endurance running began as an adaptation for scavenging and later for persistence hunting.

🔗 Time 🔗 Switzerland

Swatch Internet Time (or .beat time) is a decimal time concept introduced in 1998 by the Swatch corporation as part of their marketing campaign for their line of "Beat" watches.

Instead of hours and minutes, the mean solar day is divided into 1000 parts called ".beats". Each .beat is equal to one decimal minute in the French Revolutionary decimal time system and lasts 1 minute and 26.4 seconds (86.4 seconds) in standard time. Times are notated as a 3-digit number out of 1000 after midnight. So, for example @248 would indicate a time 248 .beats after midnight representing ​²⁴⁸⁄₁₀₀₀ of a day, just over 5 hours and 57 minutes.

There are no time zones in Swatch Internet Time; instead, the new time scale of Biel Meantime (BMT) is used, based on Swatch's headquarters in Biel, Switzerland and equivalent to Central European Time, West Africa Time, and UTC+01. Unlike civil time in Switzerland and many other countries, Swatch Internet Time does not observe daylight saving time.

🔗 Mathematics

The 100 prisoners problem is a mathematical problem in probability theory and combinatorics. In this problem, 100 numbered prisoners must find their own numbers in one of 100 drawers in order to survive. The rules state that each prisoner may open only 50 drawers and cannot communicate with other prisoners. At first glance, the situation appears hopeless, but a clever strategy offers the prisoners a realistic chance of survival. Danish computer scientist Peter Bro Miltersen first proposed the problem in 2003.

🔗 Computing 🔗 Systems 🔗 Computing/Software 🔗 Systems/Software engineering

From its beginnings in the 1960s, writing software has evolved into a profession concerned with how best to maximize the quality of software and of how to create it. Quality can refer to how maintainable software is, to its stability, speed, usability, testability, readability, size, cost, security, and number of flaws or "bugs", as well as to less measurable qualities like elegance, conciseness, and customer satisfaction, among many other attributes. How best to create high quality software is a separate and controversial problem covering software design principles, so-called "best practices" for writing code, as well as broader management issues such as optimal team size, process, how best to deliver software on time and as quickly as possible, work-place "culture", hiring practices, and so forth. All this falls under the broad rubric of software engineering.

🔗 Companies 🔗 Linguistics 🔗 Linguistics/Etymology 🔗 Indexes

This is a list of company names with their name origins explained. Some of the origins are disputed.

🔗 Russia 🔗 Russia/technology and engineering in Russia 🔗 Spaceflight 🔗 Russia/science and education in Russia 🔗 Russia/history of Russia

Soyuz 11 (Russian: Союз 11, Union 11) was the only crewed mission to board the world's first space station, Salyut 1 (Soyuz 10 had soft-docked but had not been able to enter due to latching problems). The crew, Georgy Dobrovolsky, Vladislav Volkov, and Viktor Patsayev, arrived at the space station on 7 June 1971 and departed on 29 June. The mission ended in disaster when the crew capsule depressurized during preparations for reentry, killing the three-man crew. The three crew members of Soyuz 11 are the only humans known to have died in space.

🔗 African diaspora 🔗 Oklahoma 🔗 Oklahoma/Task-force Tulsa

The Tulsa race massacre (also called the Tulsa race riot, the Greenwood Massacre, or the Black Wall Street Massacre) of 1921 took place on May 31 and June 1, 1921, when mobs of white residents attacked black residents and businesses of the Greenwood District in Tulsa, Oklahoma. It has been called "the single worst incident of racial violence in American history." The attack, carried out on the ground and from private aircraft, destroyed more than 35 square blocks of the district – at that time the wealthiest black community in the United States, known as "Black Wall Street".

More than 800 people were admitted to hospitals and as many as 6,000 black residents were interned at large facilities, many for several days. The Oklahoma Bureau of Vital Statistics officially recorded 36 dead, but the American Red Cross declined to provide an estimate. A 2001 state commission examination of events was able to confirm 39 dead, 26 black and 13 white, based on contemporary autopsy reports, death certificates and other records. The commission gave overall estimates from 75–100 to 150–300 dead.

The massacre began over Memorial Day weekend after 19-year-old Dick Rowland, a black shoeshiner, was accused of assaulting Sarah Page, the 17-year-old white elevator operator of the nearby Drexel Building. He was taken into custody. A subsequent gathering of angry local whites outside the courthouse where Rowland was being held, and the spread of rumors he had been lynched, alarmed the local black population, some of whom arrived at the courthouse armed. Shots were fired and twelve people were killed: ten white and two black. As news of these deaths spread throughout the city, mob violence exploded. White rioters rampaged through the black neighborhood that night and morning killing men and burning and looting stores and homes, and only around noon the next day Oklahoma National Guard troops managed to get control of the situation by declaring martial law. About 10,000 black people were left homeless, and property damage amounted to more than $1.5 million in real estate and $750,000 in personal property (equivalent to $32.25 million in 2019).

Many survivors left Tulsa. Black and white residents who stayed in the city were silent for decades about the terror, violence, and losses of this event. The massacre was largely omitted from local, state, and national histories.

In 1996, seventy-five years after the massacre, a bipartisan group in the state legislature authorized formation of the Oklahoma Commission to Study the Tulsa Race Riot of 1921 (renamed Oklahoma Commission to Study the Tulsa Race Massacre, in November 2018). Members were appointed to investigate events, interview survivors, hear testimony from the public, and prepare a report of events. There was an effort toward public education about these events through the process. The Commission's final report, published in 2001, said that the city had conspired with the mob of white citizens against black citizens; it recommended a program of reparations to survivors and their descendants. The state passed legislation to establish some scholarships for descendants of survivors, encourage economic development of Greenwood, and develop a memorial park in Tulsa to the massacre victims. The park was dedicated in 2010. In 2020, the massacre became part of the Oklahoma school curriculum.