Random Articles (Page 97)
Have a deep view into what people are curious about.
π Operation Freakout
Operation Freakout, also known as Operation PC Freakout, was a Church of Scientology covert plan intended to have the U.S. author and journalist Paulette Cooper imprisoned or committed to a psychiatric hospital. The plan, undertaken in 1976 following years of church-initiated lawsuits and covert harassment, was meant to eliminate the perceived threat that Cooper posed to the church and obtain revenge for her publication in 1971 of a highly critical book, The Scandal of Scientology. The Federal Bureau of Investigation discovered documentary evidence of the plot and the preceding campaign of harassment during an investigation into the Church of Scientology in 1977, eventually leading to the church compensating Cooper in an out-of-court settlement.
Discussed on
- "Operation Freakout" | 2023-12-27 | 14 Upvotes 1 Comments
π Bum Farto
Joseph "Bum" Farto (July 3, 1919 β February 16, 1976) was a fire chief and convicted drug dealer in Key West, Florida who disappeared in 1976.
Discussed on
- "Bum Farto" | 2024-08-22 | 119 Upvotes 29 Comments
π Geohash: text representation allows you to sort locations by proximity
Geohash is a public domain geocode system invented in 2008 by Gustavo Niemeyer and (similar work in 1966) G.M. Morton, which encodes a geographic location into a short string of letters and digits. It is a hierarchical spatial data structure which subdivides space into buckets of grid shape, which is one of the many applications of what is known as a Z-order curve, and generally space-filling curves.
Geohashes offer properties like arbitrary precision and the possibility of gradually removing characters from the end of the code to reduce its size (and gradually lose precision). As a consequence of the gradual precision degradation, nearby places will often (but not always) present similar prefixes. While in rare cases nearby places may have very short shared prefixes, the longer their shared prefix is, the closer two places are guaranteed to be.
Discussed on
- "Geohash" | 2023-11-12 | 44 Upvotes 15 Comments
- "Geohash: text representation allows you to sort locations by proximity" | 2014-08-23 | 39 Upvotes 8 Comments
π Type A and Type B personality theory
Type A and Type B personality hypothesis describes two contrasting personality types. In this hypothesis, personalities that are more competitive, highly organized, ambitious, impatient, highly aware of time management and/or aggressive are labeled Type A, while more relaxed, less 'neurotic', 'frantic', 'explainable', personalities are labeled Type B.
The two cardiologists who developed this theory came to believe that Type A personalities had a greater chance of developing coronary heart disease. Following the results of further studies and considerable controversy about the role of the tobacco industry funding of early research in this area, some reject, either partially or completely, the link between Type A personality and coronary disease. Nevertheless, this research had a significant effect on the development of the health psychology field, in which psychologists look at how an individual's mental state affects physical health.
Discussed on
- "Type A and Type B personality theory" | 2014-03-22 | 26 Upvotes 3 Comments
π Symmetry Minute
The symmetry minute is a significant time point in the clock face timetables used by many public transport operators. At this point in the cycle, a train in a clock-face timetable meets its counterpart travelling in the opposite direction on the same line. If this crossing time is constant across a network, connecting times between lines are kept consistent in both directions.
At the symmetry time, the timetable is mirrored in both directions. At the ends of the line, the center of the turnaround time coincides with the symmetry minute. The distance between two consecutive symmetry times is equal to half the cycle time, so on an hourly schedule, opposite trains on the same line cross every 30 minutes. On a two-hour cycle, there is a symmetry time every hour.
In principle, a train-encounter can be set at any time. However, at the transition between two networks or lines, it is expedient to set uniform symmetry minutes, to create a symmetrical connection relation. For the long-distance cycle systems of ΓBB and SBB, the Forschungsgesellschaft fΓΌr StraΓen- und Verkehrswesen fΓΌr Deutschland (Research Association for Roads and Traffic for Germany) recommends minute 58, so a four-minute minimum connecting time results in a departure at minute 0. Meanwhile, most railways in Central Europe and a number of other transport operators have established the symmetry minute 58Β½, for a three-minute hold time before a departure at minute 0. Shorter cycles have additional symmetry minutes, shifted by half the cycle time. So an hourly cycle has symmetries at minutes 28Β½ and 58Β½, a 30-minute cycle has symmetries at minutes 13Β½, 28Β½, 43Β½ and 58Β½, and so on.
The following table shows the departure times in opposite directions for an hourly cycle, using the 58Β½ symmetry minute (the most common in Central Europe). The other departure times for shorter cycles can be calculated from it. The last line gives the meeting times.
Discussed on
- "Symmetry Minute" | 2019-07-18 | 84 Upvotes 18 Comments
π --All You Zombies--
"β'βAll You Zombiesβ'β" is a science fiction short story by American writer Robert A. Heinlein. It was written in one day, July 11, 1958, and first published in the March 1959 issue of Fantasy and Science Fiction magazine after being rejected by Playboy.
The story involves a number of paradoxes caused by time travel. In 1980, it was nominated for the Balrog Award for short fiction.
"'βAll You Zombiesβ'" further develops themes explored by the author in a previous work: "By His Bootstraps", published some 18 years earlier. Some of the same elements also appear later in The Cat Who Walks Through Walls (1985), including the Circle of Ouroboros and the Temporal Corps.
The unusual title of the story, which includes both the quotation marks and dashes shown above, is a quotation from a sentence near the end of the story; the quotation is taken from the middle of the sentence, hence the dashes indicating edited text before and after the title.
Discussed on
- "All You Zombies" | 2022-02-25 | 111 Upvotes 51 Comments
- "--All You Zombies--" | 2009-12-19 | 30 Upvotes 13 Comments
- "All You Zombiesβ The most craziest of the time travel paradoxes" | 2008-10-10 | 42 Upvotes 21 Comments
π Ask HN: using only static magnetism - impossible to stably levitate against gravity?
Earnshaw's theorem states that a collection of point charges cannot be maintained in a stable stationary equilibrium configuration solely by the electrostatic interaction of the charges. This was first proven by British mathematician Samuel Earnshaw in 1842. It is usually referenced to magnetic fields, but was first applied to electrostatic fields.
Earnshaw's theorem applies to classical inverse-square law forces (electric and gravitational) and also to the magnetic forces of permanent magnets, if the magnets are hard (the magnets do not vary in strength with external fields). Earnshaw's theorem forbids magnetic levitation in many common situations.
If the materials are not hard, Braunbeck's extension shows that materials with relative magnetic permeability greater than one (paramagnetism) are further destabilising, but materials with a permeability less than one (diamagnetic materials) permit stable configurations.
Discussed on
- "Earnshaw's Theorem" | 2020-11-14 | 23 Upvotes 5 Comments
- "Ask HN: using only static magnetism - impossible to stably levitate against gravity?" | 2009-04-30 | 3 Upvotes 10 Comments
π Headlinese
Headlinese is an abbreviated form of news writing style used in newspaper headlines.
Discussed on
- "Headlinese" | 2020-02-10 | 45 Upvotes 9 Comments
π United States Camel Corps
The United States Camel Corps was a mid-19th-century experiment by the United States Army in using camels as pack animals in the Southwestern United States. While the camels proved to be hardy and well suited to travel through the region, the Army declined to adopt them for military use. The Civil War interfered with the experiment and it was eventually abandoned; the animals were sold at auction.
Discussed on
- "United States Camel Corps" | 2025-01-28 | 11 Upvotes 2 Comments
- "United States Camel Corps" | 2017-08-16 | 70 Upvotes 19 Comments
π Netpbm format
Netpbm is an open-source package of graphics programs and a programming library. It is used mainly in the Unix world, where one can find it included in all major open-source operating system distributions, but also works on Microsoft Windows, macOS, and other operating systems.
Discussed on
- "Netpbm format" | 2015-11-07 | 29 Upvotes 23 Comments