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π Marvin Pipkin, inventor of the frosted light bulb
Marvin Pipkin (November 18, 1889 β January 7, 1977) was an American chemist. During his time in the United States Army he worked on gas masks. In his civilian life he invented a process for frosting the inside of incandescent light bulbs to cut down on the sharp glare and diffuse the light. He went on to make many other inventions and innovative improvements to the light bulb.
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- "Marvin Pipkin, inventor of the frosted light bulb" | 2019-03-23 | 86 Upvotes 29 Comments
π List of journalists killed in Russia under Putin
The dangers to journalists in Russia have been well known since the early 1990s but concern over the number of unsolved killings soared after Anna Politkovskaya's murder in Moscow on 7 October 2006. While international monitors mentioned a dozen deaths, some sources within Russia talked of over two hundred fatalities. The evidence has since been examined and documented in two reports, published in Russian and English, by international organizations. These revealed a basic confusion in terminology that explained the seemingly enormous numerical discrepancy: statistics of premature death among journalists (from work accidents, crossfire incidents, and purely criminal or domestic cases of manslaughter) were repeatedly equated with the much smaller number of targeted (contract) killings or work-related murders. The Remembrance Day of Journalists Killed in the Line of Duty in Russia is observed on 15 December every year.
π Jonathan James
Jonathan Joseph James (December 12, 1983 β May 18, 2008) was an American hacker who was the first juvenile incarcerated for cybercrime in the United States. The South Florida native was 15 years old at the time of the first offense and 16 years old on the date of his sentencing. He died at his Pinecrest, Florida home on May 18, 2008, of a self-inflicted gunshot wound.
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- "Jonathan James" | 2013-01-13 | 366 Upvotes 118 Comments
π Gravity Hill
A gravity hill, also known as a magnetic hill, mystery hill, mystery spot, gravity road, or anti-gravity hill, is a place where the layout of the surrounding land produces an optical illusion, making a slight downhill slope appear to be an uphill slope. Thus, a car left out of gear will appear to be rolling uphill against gravity. There are hundreds of recognized gravity hills around the world.
The slope of gravity hills is an optical illusion, although sites are often accompanied by claims that magnetic or supernatural forces are at work. The most important factor contributing to the illusion is a completely or mostly obstructed horizon. Without a horizon, it becomes difficult to judge the slope of a surface as a reliable reference is missing. Objects which one would normally assume to be more or less perpendicular to the ground, such as trees, may actually be leaning, offsetting the visual reference.
A 2003 study looked into how the absence of a horizon can skew the perspective on gravity hills by recreating a number of antigravity places in the lab to see how volunteers would react. As a conclusion, researchers from Universities of Padova and Pavia in Italy found that without a true horizon in sight, landmarks such as trees and signs actually played these tricks on the human brain.
The illusion is similar to the Ames room, in which objects can also appear to roll against gravity.
The opposite phenomenonβan uphill road that appears flatβis known in bicycle racing as a "false flat".
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- "Gravity Hill" | 2022-03-19 | 102 Upvotes 33 Comments
π Boltzmann Brain
The Boltzmann brain argument suggests that it is more likely for a single brain to spontaneously and briefly form in a void (complete with a false memory of having existed in our universe) than it is for our universe to have come about in the way modern science thinks it actually did. It was first proposed as a reductio ad absurdum response to Ludwig Boltzmann's early explanation for the low-entropy state of our universe.
In this physics thought experiment, a Boltzmann brain is a fully formed brain, complete with memories of a full human life in our universe, that arises due to extremely rare random fluctuations out of a state of thermodynamic equilibrium. Theoretically over a period of time on the order of hundreds of billions of years, by sheer chance atoms in a void could spontaneously come together in such a way as to assemble a functioning human brain. Like any brain in such circumstances, it would almost immediately stop functioning and begin to deteriorate.
The idea is ironically named after the Austrian physicist Ludwig Boltzmann (1844β1906), who in 1896 published a theory that tried to account for the fact that we find ourselves in a universe that is not as chaotic as the budding field of thermodynamics seemed to predict. He offered several explanations, one of them being that the universe, even one that is fully random (or at thermal equilibrium), would spontaneously fluctuate to a more ordered (or low-entropy) state. One criticism of this "Boltzmann universe" hypothesis is that the most common thermal fluctuations are as close to equilibrium overall as possible; thus, by any reasonable criterion, actual humans in the actual universe would be vastly less likely than "Boltzmann brains" existing alone in an empty universe.
Boltzmann brains gained new relevance around 2002, when some cosmologists started to become concerned that, in many existing theories about the Universe, human brains in the current Universe appear to be vastly outnumbered by Boltzmann brains in the future Universe who, by chance, have exactly the same perceptions that we do; this leads to the conclusion that statistically we ourselves are likely to be Boltzmann brains. Such a reductio ad absurdum argument is sometimes used to argue against certain theories of the Universe. When applied to more recent theories about the multiverse, Boltzmann brain arguments are part of the unsolved measure problem of cosmology. Boltzmann brains remain a thought experiment; physicists do not believe that we are actually Boltzmann brains, but rather use the thought experiment as a tool for evaluating competing scientific theories.
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- "Boltzmann brain" | 2024-12-10 | 148 Upvotes 150 Comments
- "Boltzmann Brain" | 2020-01-17 | 238 Upvotes 149 Comments
- "Boltzmann Brain" | 2016-07-24 | 58 Upvotes 17 Comments
- "Boltzmann brain" | 2014-01-02 | 59 Upvotes 18 Comments
π The Population Bomb (1968)
The Population Bomb is a 1968 book co-authored by former Stanford University professor Paul R. Ehrlich and former Stanford senior researcher in conservation biology Anne H. Ehrlich. From the opening page, it predicted worldwide famines due to overpopulation, as well as other major societal upheavals, and advocated immediate action to limit population growth. Fears of a "population explosion" existed in the mid-20th century baby boom years, but the book and its authors brought the idea to an even wider audience.
The book has been criticized since its publication for an alarmist tone, and over the subsequent decades, for inaccurate assertions and failed predictions. For instance, regional famines have occurred since the publication of the book, but not world famines. The Ehrlichs themselves still stand by the book despite the flaws identified by its critics, with Paul stating in 2009 that "perhaps the most serious flaw in The Bomb was that it was much too optimistic about the future," despite having predicted catastrophic global famines that never came to pass. They believe that it achieved their goals because "it alerted people to the importance of environmental issues and brought human numbers into the debate on the human future."
π Truchet Tiles
In information visualization and graphic design, Truchet tiles are square tiles decorated with patterns that are not rotationally symmetric. When placed in a square tiling of the plane, they can form varied patterns, and the orientation of each tile can be used to visualize information associated with the tile's position within the tiling.
Truchet tiles were first described in a 1704 memoir by SΓ©bastien Truchet entitled "MΓ©moire sur les combinaisons", and were popularized in 1987 by Cyril Stanley Smith.
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- "Truchet Tiles" | 2025-07-25 | 123 Upvotes 28 Comments
π ErdΕs number
The ErdΕs number (Hungarian:Β [ΛΙrdΓΈΛΚ]) describes the "collaborative distance" between mathematician Paul ErdΕs and another person, as measured by authorship of mathematical papers. The same principle has been applied in other fields where a particular individual has collaborated with a large and broad number of peers.
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- "ErdΕs number" | 2010-09-29 | 16 Upvotes 22 Comments
π Firehose of Falsehood
The firehose of falsehood, or firehosing, is a propaganda technique in which a large number of messages are broadcast rapidly, repetitively, and continuously over multiple channels (such as news and social media) without regard for truth or consistency. Since 2014, when it was successfully used by Russia during its annexation of Crimea, this model has been adopted by other governments and political movements around the world.
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- "Firehose of Falsehood" | 2022-01-02 | 68 Upvotes 18 Comments
- "Firehose of Falsehood" | 2021-05-28 | 14 Upvotes 2 Comments
π Light Characteristic
A light characteristic is all of the properties that make a particular navigational light identifiable. Graphical and textual descriptions of navigational light sequences and colours are displayed on nautical charts and in Light Lists with the chart symbol for a lighthouse, lightvessel, buoy or sea mark with a light on it. Different lights use different colours, frequencies and light patterns, so mariners can identify which light they are seeing.
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- "Light Characteristic" | 2024-02-08 | 60 Upvotes 7 Comments