Have a deep view into what people are curious about.

🔗 Physics 🔗 Energy 🔗 Physics/Fluid Dynamics

Salter's duck, also known as the nodding duck or by its official name the Edinburgh duck, is a device that converts wave power into electricity. The wave impact induces rotation of gyroscopes located inside a pear-shaped "duck", and an electrical generator converts this rotation into electricity with an overall efficiency of up to 90%. The Salter's duck was invented by Stephen Salter in response to the oil shortage in the 1970s and was one of the earliest generator designs proposed to the Wave Energy programme in the United Kingdom. The funding for the project was cut off in the early 1980s after oil prices rebounded and the UK government moved away from alternative energy sources. As of May 2018 no wave-power devices have ever gone into large-scale production.

🔗 Iran 🔗 London 🔗 British Museum 🔗 Visual arts 🔗 Sculpture

The Oxus treasure (Persian: گنجینه آمودریا) is a collection of about 180 surviving pieces of metalwork in gold and silver, the majority rather small, plus perhaps about 200 coins, from the Achaemenid Persian period which were found by the Oxus river about 1877-1880. The exact place and date of the find remain unclear, and it is likely that many other pieces from the hoard were melted down for bullion; early reports suggest there were originally some 1500 coins, and mention types of metalwork that are not among the surviving pieces. The metalwork is believed to date from the sixth to fourth centuries BC, but the coins show a greater range, with some of those believed to belong to the treasure coming from around 200 BC. The most likely origin for the treasure is that it belonged to a temple, where votive offerings were deposited over a long period. How it came to be deposited is unknown.

As a group, the treasure is the most important survival of what was once an enormous production of Achaemenid work in precious metal. It displays a very wide range of quality of execution, with the many gold votive plaques mostly crudely executed, some perhaps by the donors themselves, while other objects are of superb quality, presumably that expected by the court.

The British Museum now has nearly all the surviving metalwork, with one of the pair of griffin-headed bracelets on loan from the Victoria and Albert Museum, and displays them in Room 52. The group arrived at the museum by different routes, with many items bequeathed to the nation by Augustus Wollaston Franks. The coins are more widely dispersed, and more difficult to firmly connect with the treasure. A group believed to come from it is in the Hermitage Museum in Saint Petersburg, and other collections have examples.

🔗 Aviation 🔗 Disaster management 🔗 Aviation/Aviation accident 🔗 Occupational Safety and Health

Aviation safety means the state of an aviation system or organization in which risks associated with aviation activities, related to, or in direct support of the operation of aircraft, are reduced and controlled to an acceptable level. It encompasses the theory, practice, investigation, and categorization of flight failures, and the prevention of such failures through regulation, education, and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel.

Aviation safety should not be confused with airport security which includes all of the measures taken to combat intentional malicious acts.

🔗 Film 🔗 France 🔗 France/Paris 🔗 Film/French cinema

100 Years is an upcoming science fiction film written by John Malkovich and directed by Robert Rodriguez. Advertised in 2015 with the tagline "The Movie You Will Never See", it is due to be released on November 18, 2115. The 100 year span matches the time it takes for a bottle of Louis XIII Cognac to be properly aged before its release to consumers. The film stars an international ensemble, with American actor John Malkovich, Taiwanese actress Shuya Chang, and Chilean actor Marko Zaror.

100 Years will apparently be a short film, Rodriguez having stated in a 2019 interview with French YouTuber InThePanda: "I was making several short films for them, and I finished that one first, we shot that one first, I thought that was gonna be a commercial or something. And then I showed them the movie and they said 'Yeah, that's great, that's great. That's the one we lock away.' And I said 'What? That's the one you lock away? What about the other one with the future--' 'No, that's the commercial.' [...] The one that I was most attached to was the one they locked away."

🔗 Metalworking

Biomachining is the machining process of using lithotropic bacteria to remove material from metal parts, contrasted with chemical machining methods such as chemical milling and physical machining methods such as milling. Certain bacteria, such as Thiobacillus ferrooxidans and Thiobacillus thiooxidans, which are also used in the mineral refinement process of bioleaching, utilize the chemical energy from oxidation of iron or copper to fix carbon dioxide from the air. A metal object, when placed in a culture fluid containing these metal-metabolizing bacteria, will have material removed from its surface over time.

Biomachining is ideal for micromachining due to its very low material removal rate. In addition, biomachining is less likely to leave an undesirable surface finish; neither chemical nor physical energy is concentrated on the cutting area, so the possibility of a damaged or burned surface is slim.

This process has been successfully used to cut both pure iron and pure copper.

🔗 Mathematics 🔗 Ancient Near East 🔗 Archaeology

YBC 7289 is a Babylonian clay tablet notable for containing an accurate sexagesimal approximation to the square root of 2, the length of the diagonal of a unit square. This number is given to the equivalent of six decimal digits, "the greatest known computational accuracy ... in the ancient world". The tablet is believed to be the work of a student in southern Mesopotamia from some time in the range from 1800–1600 BC, and was donated to the Yale Babylonian Collection by J. P. Morgan.

🔗 Anthropology 🔗 Numismatics 🔗 Trade 🔗 Micronesia 🔗 Micronesia/Federated States of Micronesia

The Micronesian island of Yap is known for its stone money, known as Rai (Yapese: raay), or Fei: large doughnut-shaped, carved disks of (usually) calcite, up to 4 m (13 ft) in diameter (most are much smaller). The smallest can be as little as 3.5 centimetres (1.4 in) in diameter. There are around 6,000 of the large, circular stone disks carved out of limestone formed from aragonite and calcite crystals. Rai stones were quarried on several of the Micronesian islands, mainly Palau, but briefly on Guam as well, and transported to Yap for use as money. They have been used in trade by the Yapese as a form of currency.

The monetary system of Yap relies on an oral history of ownership. In the case of stones that are too large to move, buying an item with one simply involves agreeing that the ownership has changed. As long as the transaction is recorded in the oral history, it will now be owned by the person to whom it is passed and no physical movement of the stone is required.

🔗 Science

In computing, tree shaking is a dead code elimination technique that is applied when optimizing code written in ECMAScript dialects like JavaScript or TypeScript into a single bundle that is loaded by a web browser. Often contrasted with traditional single-library dead code elimination techniques common to minifiers, tree shaking eliminates unused functions from across the bundle by starting at the entry point and only including functions that may be executed. It is succinctly described as "live code inclusion".

🔗 Physics 🔗 Physics/relativity

In theoretical physics, particularly in discussions of gravitation theories, Mach's principle (or Mach's conjecture) is the name given by Einstein to an imprecise hypothesis often credited to the physicist and philosopher Ernst Mach. The hypothesis attempted to explain how rotating objects, such as gyroscopes and spinning celestial bodies, maintain a frame of reference.

The proposition is that the existence of absolute rotation (the distinction of local inertial frames vs. rotating reference frames) is determined by the large-scale distribution of matter, as exemplified by this anecdote:

You are standing in a field looking at the stars. Your arms are resting freely at your side, and you see that the distant stars are not moving. Now start spinning. The stars are whirling around you and your arms are pulled away from your body. Why should your arms be pulled away when the stars are whirling? Why should they be dangling freely when the stars don't move?

Mach's principle says that this is not a coincidence—that there is a physical law that relates the motion of the distant stars to the local inertial frame. If you see all the stars whirling around you, Mach suggests that there is some physical law which would make it so you would feel a centrifugal force. There are a number of rival formulations of the principle, often stated in vague ways like "mass out there influences inertia here". A very general statement of Mach's principle is "local physical laws are determined by the large-scale structure of the universe".

Mach's concept was a guiding factor in Einstein's development of the general theory of relativity. Einstein realized that the overall distribution of matter would determine the metric tensor which indicates which frame is stationary with respect to rotation. Frame-dragging and conservation of gravitational angular momentum makes this into a true statement in the general theory in certain solutions. But because the principle is so vague, many distinct statements have been made which would qualify as a Mach principle, and some of which are false. The Gödel rotating universe is a solution of the field equations that is designed to disobey Mach's principle in the worst possible way. In this example, the distant stars seem to be revolving faster and faster as one moves further away. This example does not completely settle the question of the physical relevance of the principle because it has closed timelike curves.

🔗 Statistics 🔗 Books 🔗 Project-independent assessment

How to Lie with Statistics is a book written by Darrell Huff in 1954, presenting an introduction to statistics for the general reader. Not a statistician, Huff was a journalist who wrote many how-to articles as a freelancer.

The book is a brief, breezy illustrated volume outlining the misuse of statistics and errors in the interpretation of statistics, and how errors create incorrect conclusions.

In the 1960s and 1970s, it became a standard textbook introduction to the subject of statistics for many college students. It has become one of the best-selling statistics books in history, with over one and a half million copies sold in the English-language edition. It has also been widely translated.

Themes of the book include "Correlation does not imply causation" and "Using random sampling." It also shows how statistical graphs can be used to distort reality. For example, by truncating the bottom of a line or bar chart so that differences seem larger than they are. Or, by representing one-dimensional quantities on a pictogram by two- or three-dimensional objects to compare their sizes so that the reader forgets that the images do not scale the same way the quantities do.

The original edition contained illustrations by artist Irving Geis. In a UK edition, Geis' illustrations were replaced by cartoons by Mel Calman.