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🔗 Metalworking 🔗 Measurement

A thousandth of an inch is a derived unit of length in a system of units using inches. Equal to 1⁄1000 of an inch, a thousandth is commonly called a thou (used for both singular and plural) or particularly in North America a mil (plural mils).

The words are shortened forms of the English and Latin words for "thousand" (mille in Latin). In international engineering contexts, confusion can arise because mil is a formal unit name in North America but mil or mill is also a common colloquial clipped form of millimetre. The units are considerably different: a millimetre is approximately 39 mils.

🔗 Philosophy 🔗 Classical Greece and Rome 🔗 Greece 🔗 Philosophy/Ancient philosophy 🔗 Philosophy/Epistemology

Pyrrhonism is an Ancient Greek school of philosophical skepticism which rejects dogma and advocates the suspension of judgement over the truth of all beliefs. It was founded by Aenesidemus in the first century BCE, and said to have been inspired by the teachings of Pyrrho and Timon of Phlius in the fourth century BCE. Pyrrhonism is best known today through the surviving works of Sextus Empiricus, writing in the late second century or early third century CE. The publication of Sextus' works in the Renaissance ignited a revival of interest in Skepticism and played a major role in Reformation thought and the development of early modern philosophy.

🔗 Espionage 🔗 Books 🔗 Computer Security 🔗 Computer Security/Computing

The Cuckoo's Egg: Tracking a Spy Through the Maze of Computer Espionage is a 1989 book written by Clifford Stoll. It is his first-person account of the hunt for a computer hacker who broke into a computer at the Lawrence Berkeley National Laboratory (LBNL).

Stoll's use of the term extended the metaphor Cuckoo's egg from brood parasitism in birds to malware.

🔗 Physics 🔗 Philosophy 🔗 Philosophy/Philosophy of science 🔗 Sociology

The term physics envy is used to criticize modern writing and research of academics working in areas such as "softer sciences", liberal arts, business studies, and humanities. The term argues that writing and working practices in these disciplines have overused confusing jargon and complicated mathematics to seem more 'rigorous' and like mathematics-based subjects like physics.

🔗 Mathematics 🔗 Economics 🔗 Politics 🔗 Elections and Referendums

In social choice theory, Arrow's impossibility theorem, the general possibility theorem or Arrow's paradox is an impossibility theorem stating that when voters have three or more distinct alternatives (options), no ranked voting electoral system can convert the ranked preferences of individuals into a community-wide (complete and transitive) ranking while also meeting a specified set of criteria: unrestricted domain, non-dictatorship, Pareto efficiency, and independence of irrelevant alternatives. The theorem is often cited in discussions of voting theory as it is further interpreted by the Gibbard–Satterthwaite theorem. The theorem is named after economist and Nobel laureate Kenneth Arrow, who demonstrated the theorem in his doctoral thesis and popularized it in his 1951 book Social Choice and Individual Values. The original paper was titled "A Difficulty in the Concept of Social Welfare".

In short, the theorem states that no rank-order electoral system can be designed that always satisfies these three "fairness" criteria:

• If every voter prefers alternative X over alternative Y, then the group prefers X over Y.
• If every voter's preference between X and Y remains unchanged, then the group's preference between X and Y will also remain unchanged (even if voters' preferences between other pairs like X and Z, Y and Z, or Z and W change).
• There is no "dictator": no single voter possesses the power to always determine the group's preference.

Cardinal voting electoral systems are not covered by the theorem, as they convey more information than rank orders. However, Gibbard's theorem extends Arrow's theorem for that case. The theorem can also be sidestepped by weakening the notion of independence.

The axiomatic approach Arrow adopted can treat all conceivable rules (that are based on preferences) within one unified framework. In that sense, the approach is qualitatively different from the earlier one in voting theory, in which rules were investigated one by one. One can therefore say that the contemporary paradigm of social choice theory started from this theorem.

The practical consequences of the theorem are debatable: Arrow has said "Most systems are not going to work badly all of the time. All I proved is that all can work badly at times."

🔗 Mathematics 🔗 Physics 🔗 Philosophy

Norton's dome is a thought experiment that exhibits a non-deterministic system within the bounds of Newtonian mechanics. It was devised by John D. Norton in 2003. It is a special limiting case of a more general class of examples from 1997 due to Sanjay Bhat and Dennis Bernstein. The Norton's dome problem can be regarded as a problem in physics, mathematics, or philosophy.

🔗 Physics

Separation of isotopes by laser excitation (SILEX) is a process for isotope separation that is being investigated to produce enriched uranium on an industrial scale using lasers. It was developed in the 1990s and is a variant of molecular laser isotope separation (MLIS). For uranium, it uses a cold molecular beam with UF₆ in a carrier cas, in which the ²³⁵UF₆ is selectively excited by an infrared laser near 16 µm. But in contrast to earlier MLIS techniques developed since the 1970s, it does not dissociate the molecule.

🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation

Balloon busters were military pilots known for destroying enemy observation balloons. These pilots were noted for their fearlessness, as balloons were stationary targets able to receive heavy defenses, from the ground and the air. Seventy-seven flying aces in World War I were each credited with destroying five or more balloons, and thus were balloon aces.

🔗 Germany 🔗 Songs 🔗 Anti-war

"99 Luftballons" (German: Neunundneunzig Luftballons, "99 balloons") is a song by the German band Nena from their 1983 self-titled album. An English-language version titled "99 Red Balloons", with lyrics by Kevin McAlea, was also released on the album 99 Luftballons in 1984 after widespread success of the original in Europe and Japan. The English version is not a direct translation of the German original and contains lyrics but with the same meaning. In the US, the English-language version did not chart, while the German-language recording became Nena's only US hit.