Have a deep view into what people are curious about.

🔗 Mathematics

The 15-puzzle (also called Gem Puzzle, Boss Puzzle, Game of Fifteen, Mystic Square and many others) is a sliding puzzle that consists of a frame of numbered square tiles in random order with one tile missing. The puzzle also exists in other sizes, particularly the smaller 8-puzzle. If the size is 3×3 tiles, the puzzle is called the 8-puzzle or 9-puzzle, and if 4×4 tiles, the puzzle is called the 15-puzzle or 16-puzzle named, respectively, for the number of tiles and the number of spaces. The object of the puzzle is to place the tiles in order by making sliding moves that use the empty space.

The n-puzzle is a classical problem for modelling algorithms involving heuristics. Commonly used heuristics for this problem include counting the number of misplaced tiles and finding the sum of the taxicab distances between each block and its position in the goal configuration. Note that both are admissible, i.e. they never overestimate the number of moves left, which ensures optimality for certain search algorithms such as A*.

🔗 Computing 🔗 Computer science

Ousterhout's dichotomy is computer scientist John Ousterhout's categorization that high-level programming languages tend to fall into two groups, each with distinct properties and uses: system programming languages and scripting languages – compare programming in the large and programming in the small. This distinction underlies the design of his language Tcl.

System programming languages (or applications languages) usually have the following properties:

• They are typed statically
• They support creating complex data structures
• Programs in them are compiled into machine code
• Programs in them are meant to operate largely independently of other programs

System programming languages tend to be used for components and applications with large amounts of internal functionality such as operating systems, database servers, and Web browsers. These applications typically employ complex algorithms and data structures and require high performance. Prototypical examples of system programming languages include C and Modula-2.

By contrast, scripting languages (or glue languages) tend to have the following properties:

• They are typed dynamically
• They have little or no provision for complex data structures
• Programs in them (scripts) are interpreted

Scripting languages tend to be used for applications where most of the functionality comes from other programs (often implemented in system programming languages); the scripts are used to glue together other programs or add additional layers of functionality on top of existing programs. Ousterhout claims that scripts tend to be short and are often written by less sophisticated programmers, so execution efficiency is less important than simplicity and ease of interaction with other programs. Common applications for scripting include Web page generation, report generation, graphical user interfaces, and system administration. Prototypical examples of scripting languages include AppleScript, C shell, DOS batch files, and Tcl.

🔗 Languages 🔗 Constructed languages

Ithkuil is an experimental constructed language created by John Quijada. It is designed to express deeper levels of human cognition briefly yet overtly and clearly, particularly with regard to human categorization. It is a cross between an a priori philosophical and a logical language. It tries to minimize the vagueness and semantic ambiguity found in natural human languages. Ithkuil is notable for its grammatical complexity and extensive phoneme inventory, the latter being simplified in an upcoming redesign. The name "Ithkuil" is an anglicized form of Iţkuîl, which in the original form roughly means "hypothetical representation of a language". Quijada states he did not create Ithkuil to be auxiliary or used in everyday conversations. He wanted the language to be used for more elaborate and profound fields where more insightful thoughts are expected, such as philosophy, arts, science and politics.

Meaningful phrases or sentences can usually be expressed in Ithkuil with fewer linguistic units than in natural languages. For example, the two-word Ithkuil sentence "Tram-mļöi hhâsmařpţuktôx" can be translated into English as "On the contrary, I think it may turn out that this rugged mountain range trails off at some point". Quijada deems his creation as too complex to have developed naturally, seeing it as an exercise in exploring how languages could function. No person, including Quijada himself, is known to be able to speak Ithkuil fluently. It was featured in the Language Creation Conference's 6th Conlang Relay.

Four versions of the language have been publicized: the initial version in 2004, a simplified version called Ilaksh in 2007, the current version in 2011, and as of 2017, various revisions of a new version of the language, named Ithkuil IV. In 2004—and again in 2009 with Ilaksh—Ithkuil was featured in the Russian-language popular science and IT magazine Computerra. In 2008, David Peterson awarded it the Smiley Award. In 2013, Bartłomiej Kamiński codified the language to be able to quickly parse complicated sentences. Julien Tavernier and anonymous others have followed suit. Since July 2015, Quijada has released several Ithkuil songs in a prog rock style as part of the album Kaduatán, which translates to "Wayfarers". Recently, online communities for the language have developed in English, Russian, Mandarin, and Japanese.

🔗 Photography 🔗 Photography/History of photography 🔗 Gemology and Jewelry

A stanhope or stanho-scope is an optical device that enables the viewing of microphotographs without using a microscope. They were invented by René Dagron in 1857. Dagron bypassed the need for an expensive microscope to view the microscopic photographs by attaching the microphotograph at the end of a modified Stanhope lens. He called the devices bijoux photo-microscopiques or microscopic photo-jewelry.

🔗 United States 🔗 Biography 🔗 Mexico 🔗 Biography/science and academia 🔗 India 🔗 Plants 🔗 United States/Texas 🔗 Science Policy

Norman Ernest Borlaug (; March 25, 1914 – September 12, 2009) was an American agronomist who led initiatives worldwide that contributed to the extensive increases in agricultural production termed the Green Revolution. Borlaug was awarded multiple honors for his work, including the Nobel Peace Prize, the Presidential Medal of Freedom and the Congressional Gold Medal.

Borlaug received his B.S. in forestry in 1937 and Ph.D. in plant pathology and genetics from the University of Minnesota in 1942. He took up an agricultural research position in Mexico, where he developed semi-dwarf, high-yield, disease-resistant wheat varieties. During the mid-20th century, Borlaug led the introduction of these high-yielding varieties combined with modern agricultural production techniques to Mexico, Pakistan, and India. As a result, Mexico became a net exporter of wheat by 1963. Between 1965 and 1970, wheat yields nearly doubled in Pakistan and India, greatly improving the food security in those nations.

Borlaug was often called "the father of the Green Revolution", and is credited with saving over a billion people worldwide from starvation. According to Jan Douglas, executive assistant to the president of the World Food Prize Foundation, the source of this number is Gregg Easterbrook's 1997 article "Forgotten Benefactor of Humanity." The article states that the "form of agriculture that Borlaug preaches may have prevented a billion deaths." He was awarded the Nobel Peace Prize in 1970 in recognition of his contributions to world peace through increasing food supply.

Later in his life, he helped apply these methods of increasing food production in Asia and Africa.

🔗 Books

The Hacker's Diet (humorously subtitled "How to lose weight and hair through stress and poor nutrition") is a diet plan created by the founder of Autodesk, John Walker, outlined in an electronic book of the same name, that attempts to aid the process of weight loss by more accurately modeling how calories consumed and calories expended actually impact weight. Walker notes that much of our fat free mass introduces signal noise when trying to determine how much weight we're actually losing or gaining. With the help of a graphing tool (Excel is used in the book), he addresses these problems. Factoring in exercise, and through counting calories, one can calculate one's own total energy expenditure (basal metabolic rate, thermic effect of food, and day-to-day exercise) and cut back calorie intake or increase exercise to lose weight.

🔗 Philosophy 🔗 Books 🔗 Philosophy/Philosophy of science 🔗 Science

The Two Cultures is the first part of an influential 1959 Rede Lecture by British scientist and novelist C. P. Snow which were published in book form as The Two Cultures and the Scientific Revolution the same year. Its thesis was that science and the humanities which represented "the intellectual life of the whole of western society" had become split into "two cultures" and that this division was a major handicap to both in solving the world's problems.

🔗 Medicine 🔗 Iran 🔗 History of Science 🔗 Middle Ages 🔗 Islam 🔗 Middle Ages/History 🔗 Turkey

A bimaristan (Persian: بيمارستان‎, romanized: bīmārestān; Arabic: بِيْمَارِسْتَان‎, romanized: bīmāristān), also known as dar al-shifa (also darüşşifa in Turkish) or simply maristan, is a hospital in the historic Islamic world.

🔗 Internet 🔗 Computing 🔗 Computing/Software 🔗 Websites 🔗 Websites/Computing 🔗 Computing/Computer Security 🔗 Computing/Websites

Evercookie is a JavaScript-based application created by Samy Kamkar that produces zombie cookies in a web browser that are intentionally difficult to delete. In 2013, a top-secret NSA document was leaked by Edward Snowden, citing Evercookie as a method of tracking Tor users.