Have a deep view into what people are curious about.

🔗 Aviation 🔗 Aviation/aircraft

The Boom XB-1 Baby Boom is a one-third-scale supersonic demonstrator designed by Boom Technology, designed as part of development of the Boom Overture supersonic transport airliner. It is planned to maintain Mach 2.2, with over 1,000 nmi (1,900 km) of range. Powered by three 4,300 lbf (19 kN) dry General Electric CJ610s, it is expected to be flight tested in 2020.

🔗 History 🔗 Lists 🔗 Geography 🔗 Israel 🔗 Palestine

The population of the region of Palestine, which approximately corresponds to modern Israel, the Palestinian territories and Jordan, has varied in both size and ethnic composition throughout its history.

The following table shows the total population and that of the main ethno-religious groups living in the area from the First Century CE up until the last full calendar year of the British Mandate, 1947.

Note: Figures prior to the 1500s are all only estimates by researchers. For some periods, there are multiple researchers who have made differing estimates. None should be taken as exact numbers, and further context and detail is available by following links to the full description on Wikipedia as well as links to the original information sources.

^†including what is today the Kingdom of Jordan

🔗 Skepticism 🔗 Paranormal

Jimmy Carter, United States president from 1977 until 1981, reported seeing an unidentified flying object while at Leary, Georgia, in 1969. While serving as governor of Georgia, Carter was asked (on September 14, 1973) by the International UFO Bureau in Oklahoma City to file a report of the sighting, and he filed a statement on September 18, mailed September 20. Since its writing, the report has been discussed several times by both ufologists and by members of the mainstream media.

🔗 Lists 🔗 History of Science 🔗 Science

Historians and sociologists have remarked the occurrence, in science, of "multiple independent discovery". Robert K. Merton defined such "multiples" as instances in which similar discoveries are made by scientists working independently of each other. "Sometimes," writes Merton, "the discoveries are simultaneous or almost so; sometimes a scientist will make a new discovery which, unknown to him, somebody else has made years before."

Commonly cited examples of multiple independent discovery are the 17th-century independent formulation of calculus by Isaac Newton, Gottfried Wilhelm Leibniz and others, described by A. Rupert Hall; the 18th-century discovery of oxygen by Carl Wilhelm Scheele, Joseph Priestley, Antoine Lavoisier and others; and the theory of the evolution of species, independently advanced in the 19th century by Charles Darwin and Alfred Russel Wallace.

Multiple independent discovery, however, is not limited to such famous historic instances. Merton believed that it is multiple discoveries, rather than unique ones, that represent the common pattern in science.

Merton contrasted a "multiple" with a "singleton"—a discovery that has been made uniquely by a single scientist or group of scientists working together.

A distinction is drawn between a discovery and an invention, as discussed for example by Bolesław Prus. However, discoveries and inventions are inextricably related, in that discoveries lead to inventions, and inventions facilitate discoveries; and since the same phenomenon of multiplicity occurs in relation to both discoveries and inventions, this article lists both multiple discoveries and multiple inventions.

🔗 Trains 🔗 Trains/Operations

Signalling block systems enable the safe and efficient operation of railways by preventing collisions between trains. The basic principle is that a route is broken up into a series of sections or "blocks". Only one train may occupy a block at a time, and the blocks are sized to allow a train to stop within them. That ensures that a train always has time to stop before getting dangerously close to another train on the same line. The block system is referred to in the UK as the method of working, in the US as the method of operation, and in Australia as safeworking.

In most situations, a system of signals is used to control the passage of trains between the blocks. When a train enters a block, signals at both ends change to indicate that the block is occupied, typically using red lamps or indicator flags. When a train first enters a block, the rear of the same train has not yet left the previous block, so both blocks are marked as occupied. That ensures there is slightly less than one block length on either end of the train that is marked as occupied, so any other train approaching that section will have enough room to stop in time, even if the first train has stopped dead on the tracks. The previously-occupied block will only be marked unoccupied when the end of the train has entirely left it, leaving the entire block clear.

Block systems have the disadvantage that they limit the number of trains on a particular route to something fewer than the number of blocks. Since the route has a fixed length, increasing the number of trains requires the creation of more blocks, which means the blocks are shorter and trains have to operate at lower speeds in order to stop safely. As a result, the number and size of blocks are closely related to the overall route capacity, and cannot be changed easily because expensive alterations to the signals along the line would be required.

Block systems are used to control trains between stations and yards, but not normally within the yards, where some other method is used. Any block system is defined by its associated physical equipment and by the application of a relevant set of rules. Some systems involve the use of signals while others do not. Some systems are specifically designed for single track railways, on which there is a danger of both head-on and rear-end collision, as opposed to double track, on which the main danger is rear-end collisions.

🔗 Philosophy 🔗 Philosophy/Logic

Buridan's ass is an illustration of a paradox in philosophy in the conception of free will. It refers to a hypothetical situation wherein an ass that is equally hungry and thirsty is placed precisely midway between a stack of hay and a pail of water. Since the paradox assumes the ass will always go to whichever is closer, it dies of both hunger and thirst since it cannot make any rational decision between the hay and water. A common variant of the paradox substitutes two identical piles of hay for the hay and water; the ass, unable to choose between the two, dies of hunger.

The paradox is named after the 14th-century French philosopher Jean Buridan, whose philosophy of moral determinism it satirizes. Although the illustration is named after Buridan, philosophers have discussed the concept before him, notably Aristotle, who used the example of a man equally hungry and thirsty, and Al-Ghazali, who used a man faced with the choice of equally good dates.

A version of this situation appears as metastability in digital electronics, when a circuit must decide between two states based on an input that is in itself undefined (neither zero nor one). Metastability becomes a problem if the circuit spends more time than it should in this "undecided" state, which is usually set by the speed of the clock the system is using.

🔗 Soviet Union 🔗 Russia 🔗 History 🔗 Russia/sports and games in Russia 🔗 Gymnastics

The Korbut flip is a gymnastics skill performed on either of two different apparatus. Both were first performed internationally by the Soviet gymnast Olga Korbut.

The more spectacular version of the skill used to be performed on the uneven bars, where the gymnast, from a stand on the high bar, performs a back flip and regrasps the bar. Korbut performed the move at the 1972 Summer Olympics, where it was the first backward release move performed on the uneven bars in international competition. In 1977, Soviet gymnast Elena Mukhina modified the flip by adding a full twist. The movement was later modified in the 1980s when it was performed towards the low bar; that is, the gymnast's flip takes place above the low bar. The Code of Points was later modified to ban standing on the high bar during routines.

The skill is also performed on the balance beam. The move is performed from a standing position and is landed in a straddled position on the beam. This movement has been modified to include twists and piked or tucked legs and is frequently performed in sequence with other movements. Unlike its counterpart on the uneven bars, the Korbut flip on beam is today considered a relatively simple skill, valued at only a "B" level in the 2017 Code of Points.

Other gymnasts who have performed the skill's uneven bars variation include Radka Zemanova (1980), Steffi Kraker (1977), Emily May (1981), Lyubov Bogdanova (1974) and Natalia Shaposhnikova (1976).

🔗 Computing 🔗 Computing/Computer hardware

The floppy disk is a data storage and transfer medium that was ubiquitous from the mid-1970s well into the 2000s. Besides the 3½-inch and 5¼-inch formats used in IBM PC compatible systems, or the 8-inch format that preceded them, many proprietary floppy disk formats were developed, either using a different disk design or special layout and encoding methods for the data held on the disk.

🔗 Computing 🔗 Mathematics 🔗 Computing/Networking

In mathematics, the Cheeger constant (also Cheeger number or isoperimetric number) of a graph is a numerical measure of whether or not a graph has a "bottleneck". The Cheeger constant as a measure of "bottleneckedness" is of great interest in many areas: for example, constructing well-connected networks of computers, card shuffling. The graph theoretical notion originated after the Cheeger isoperimetric constant of a compact Riemannian manifold.

The Cheeger constant is named after the mathematician Jeff Cheeger.

🔗 Politics

In political jargon, a self-licking ice cream cone is a self-perpetuating system that has no purpose other than to sustain itself. The phrase appeared to have been first used in 1992, in On Self-Licking Ice Cream Cones, a paper by Pete Worden about NASA's bureaucracy. James A. Vedda described it as "Why do humans go into space? So we can go farther into space!"

Since then, the term has been used to describe the habit of government funded organisations and programs spending taxpayer money to lobby for more funding from the taxpayer. Other things compared have included financial bubbles, chatshows and reality television. In The Irish Times, Kevin Courtney observed that "many organisations are also stuck in limbo, destined to keep lurching on without ever achieving their stated goal. That’s because their real goal is simply to carry on regardless." The Cold War infrastructure has also been compared to a self-licking ice cream cone, given that expensive projects continued to be financed long after world communism had ceased to pose a viable threat.

Richard Hoggart used the term to describe certain United Nations programmes.

In sport, the Bowl Alliance was criticised using the term.