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🔗 The Demon-Haunted World
The Demon-Haunted World: Science as a Candle in the Dark is a 1995 book by the astronomer and science communicator Carl Sagan. (Four of the 25 chapters were written with Ann Druyan.) In it, Sagan aims to explain the scientific method to laypeople and to encourage people to learn critical and skeptical thinking. He explains methods to help distinguish between ideas that are considered valid science and those that can be considered pseudoscience. Sagan states that when new ideas are offered for consideration, they should be tested by means of skeptical thinking and should stand up to rigorous questioning.
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- "The Demon-Haunted World" | 2025-09-28 | 188 Upvotes 100 Comments
🔗 World's Littlest Skyscraper
The Newby–McMahon Building, commonly referred to as the world's littlest skyscraper, is located at 701 La Salle (on the corner of Seventh and La Salle streets) in downtown Wichita Falls, Texas. It is a late Neoclassical style red brick and cast stone structure. It stands 40 ft (12 m) tall, and its exterior dimensions are 18 ft (5.5 m) deep and 10 ft (3.0 m) wide. Its interior dimensions are approximately 12 ft (3.7 m) by 9 ft (2.7 m), or approximately 108 sq ft (10.0 m2). Steep, narrow, internal stairways leading to the upper floors occupy roughly 25 percent of the interior area.
Reportedly the result of a fraudulent investment scheme by a confidence man, the Newby–McMahon Building was a source of great embarrassment to the city and its residents after its completion in 1919. During the 1920s, the Newby–McMahon Building was featured in Robert Ripley's Ripley's Believe It or Not! syndicated column as "the world's littlest skyscraper," a nickname that has stuck with it ever since. The Newby–McMahon Building is now part of the Depot Square Historic District of Wichita Falls, a Texas Historic Landmark.
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- "World's Littlest Skyscraper" | 2021-03-13 | 131 Upvotes 49 Comments
🔗 The "DeWitt Clause"
David J. DeWitt is a computer scientist specializing in database management system research at the Massachusetts Institute of Technology. Prior to moving to MIT, DeWitt was the John P. Morgridge Professor (Emeritus) of Computer Sciences at the University of Wisconsin–Madison. He was also a Technical Fellow at Microsoft, leading the Microsoft Jim Gray Systems Lab at Madison, Wisconsin. Professor DeWitt received a B.A. degree from Colgate University in 1970, and a Ph.D. from the University of Michigan in 1976. He then joined the University of Wisconsin-Madison and started the Wisconsin Database Group, which he led for more than 30 years.
Professor DeWitt is known for his research in the areas of parallel databases, benchmarking, object-oriented databases, and XML databases. He is an elected member of the National Academy of Engineering (1998), and a Fellow of the Association for Computing Machinery.
He received the ACM SIGMOD Innovations Award (now renamed SIGMOD Edgar F. Codd Innovations Award) in 1995 for his contributions to the database systems field. In 2009, ACM recognized the seminal contributions of his Gamma parallel database system project with the ACM Software System Award. Also in 2009, he received the IEEE Emanuel R. Piore Award for his contributions to the database systems field.
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- "The "DeWitt Clause"" | 2013-12-15 | 19 Upvotes 1 Comments
🔗 Bloom's 2 sigma problem
Bloom's 2 sigma problem refers to an educational phenomenon observed by educational psychologist Benjamin Bloom and initially reported in 1984 in the journal Educational Researcher. Bloom found that the average student tutored one-to-one using mastery learning techniques performed two standard deviations better than students who learn via conventional instructional methods — that is, "the average tutored student was above 98% of the students in the control class". Additionally, the variation of the students' achievement changed: "about 90% of the tutored students ... attained the level of summative achievement reached by only the highest 20%" of the control class. Bloom's graduate students J. Anania and A. J. Burke conducted studies of this effect at different grade levels and in different schools, observing students with "great differences in cognitive achievement, attitudes, and academic self-concept".
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- "Bloom's 2 Sigma Problem" | 2023-02-25 | 266 Upvotes 130 Comments
- "Bloom's 2 Sigma Problem" | 2020-08-24 | 54 Upvotes 15 Comments
- "Bloom's 2 sigma problem" | 2018-10-01 | 57 Upvotes 18 Comments
🔗 Polyphasic Sleep
Biphasic sleep (or diphasic, bimodal or bifurcated sleep) is the practice of sleeping during two periods over the course of 24 hours, while polyphasic sleep refers to sleeping multiple times – usually more than two. Each of these is in contrast to monophasic sleep, which is one period of sleep within 24 hours. Segmented sleep and divided sleep may refer to polyphasic or biphasic sleep, but may also refer to interrupted sleep, where the sleep has one or several shorter periods of wakefulness. A common form of biphasic or polyphasic sleep includes a nap, which is a short period of sleep, typically taken between the hours of 9 am and 9 pm as an adjunct to the usual nocturnal sleep period. Nowadays, the definition of polyphasic sleep is any sleep schedule with at least two sleeps per day, to distinguish it from monophasic sleep, which only has one sleep per day.
The term polyphasic sleep was first used in the early 20th century by psychologist J. S. Szymanski, who observed daily fluctuations in activity patterns (see Stampi 1992). It does not imply any particular sleep schedule. The circadian rhythm disorder known as irregular sleep-wake syndrome is an example of polyphasic sleep in humans. Polyphasic sleep is common in many animals, and is believed to be the ancestral sleep state for mammals, although simians are monophasic.
The term polyphasic sleep is also used by an online community that experiments with alternative sleeping schedules to achieve more time awake each day. However, researchers such as Piotr Woźniak warn that such forms of sleep deprivation are not healthy. While many claim that polyphasic sleep was widely used by some polymaths and prominent people such as Leonardo da Vinci, Napoleon, and Nikola Tesla, there are few reliable sources supporting that view.
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- "Polyphasic Sleep" | 2013-08-22 | 32 Upvotes 44 Comments
🔗 Circle-Ellipse Problem
The circle–ellipse problem in software development (sometimes called the square–rectangle problem) illustrates several pitfalls which can arise when using subtype polymorphism in object modelling. The issues are most commonly encountered when using object-oriented programming (OOP). By definition, this problem is a violation of the Liskov substitution principle, one of the SOLID principles.
The problem concerns which subtyping or inheritance relationship should exist between classes which represent circles and ellipses (or, similarly, squares and rectangles). More generally, the problem illustrates the difficulties which can occur when a base class contains methods which mutate an object in a manner which may invalidate a (stronger) invariant found in a derived class, causing the Liskov substitution principle to be violated.
The existence of the circle–ellipse problem is sometimes used to criticize object-oriented programming. It may also imply that hierarchical taxonomies are difficult to make universal, implying that situational classification systems may be more practical.
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- "Circle-Ellipse Problem" | 2011-04-17 | 21 Upvotes 20 Comments
🔗 No free lunch in search and optimization
In computational complexity and optimization the no free lunch theorem is a result that states that for certain types of mathematical problems, the computational cost of finding a solution, averaged over all problems in the class, is the same for any solution method. The name alludes to the saying "no such thing as a free lunch", that is, no method offers a "short cut". This is under the assumption that the search space is a probability density function. It does not apply to the case where the search space has underlying structure (e.g., is a differentiable function) that can be exploited more efficiently (e.g., Newton's method in optimization) than random search or even has closed-form solutions (e.g., the extrema of a quadratic polynomial) that can be determined without search at all. For such probabilistic assumptions, the outputs of all procedures solving a particular type of problem are statistically identical. A colourful way of describing such a circumstance, introduced by David Wolpert and William G. Macready in connection with the problems of search and optimization, is to say that there is no free lunch. Wolpert had previously derived no free lunch theorems for machine learning (statistical inference). Before Wolpert's article was published, Cullen Schaffer independently proved a restricted version of one of Wolpert's theorems and used it to critique the current state of machine learning research on the problem of induction.
In the "no free lunch" metaphor, each "restaurant" (problem-solving procedure) has a "menu" associating each "lunch plate" (problem) with a "price" (the performance of the procedure in solving the problem). The menus of restaurants are identical except in one regard – the prices are shuffled from one restaurant to the next. For an omnivore who is as likely to order each plate as any other, the average cost of lunch does not depend on the choice of restaurant. But a vegan who goes to lunch regularly with a carnivore who seeks economy might pay a high average cost for lunch. To methodically reduce the average cost, one must use advance knowledge of a) what one will order and b) what the order will cost at various restaurants. That is, improvement of performance in problem-solving hinges on using prior information to match procedures to problems.
In formal terms, there is no free lunch when the probability distribution on problem instances is such that all problem solvers have identically distributed results. In the case of search, a problem instance in this context is a particular objective function, and a result is a sequence of values obtained in evaluation of candidate solutions in the domain of the function. For typical interpretations of results, search is an optimization process. There is no free lunch in search if and only if the distribution on objective functions is invariant under permutation of the space of candidate solutions. This condition does not hold precisely in practice, but an "(almost) no free lunch" theorem suggests that it holds approximately.
🔗 Alan Smithee
Alan Smithee (also Allen Smithee) is an official pseudonym used by film directors who wish to disown a project. Coined in 1968 and used until it was formally discontinued in 2000, it was the sole pseudonym used by members of the Directors Guild of America (DGA) when a director, dissatisfied with the final product, proved to the satisfaction of a guild panel that they had not been able to exercise creative control over a film. The director was also required by guild rules not to discuss the circumstances leading to the movie or even to acknowledge being the project's director.
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- "Alan Smithee" | 2018-07-09 | 38 Upvotes 9 Comments
🔗 Nobel Disease
Nobel disease or Nobelitis is the embracing of strange or scientifically unsound ideas by some Nobel Prize winners, usually later in life. It has been argued that the effect results, in part, from a tendency for Nobel winners to feel empowered by the award to speak on topics outside their specific area of expertise, although it is unknown whether Nobel Prize winners are more prone to this tendency than other individuals. Paul Nurse, co-winner of the 2001 Nobel Prize in Physiology or Medicine, warned later laureates against "believing you are expert in almost everything, and being prepared to express opinions about most issues with great confidence, sheltering behind the authority that the Nobel Prize can give you". Nobel disease has been described as a "tongue in cheek" term.
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- "Nobel Disease" | 2026-08-04 | 124 Upvotes 131 Comments
- "Nobel Disease" | 2023-07-15 | 12 Upvotes 4 Comments
- "Nobel Disease" | 2021-09-29 | 23 Upvotes 5 Comments
🔗 Centennial Light
The Centennial Light is the world's longest-lasting light bulb, burning since 1901, and almost never switched off. It is at 4550 East Avenue, Livermore, California, and maintained by the Livermore-Pleasanton Fire Department. Due to its longevity, the bulb has been noted by The Guinness Book of World Records, Ripley's Believe It or Not!, and General Electric.
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- "Centennial Light" | 2019-07-13 | 40 Upvotes 20 Comments