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π Year Without a Summer
The year 1816 is known as the Year Without a Summer (also the Poverty Year and Eighteen Hundred and Froze To Death) because of severe climate abnormalities that caused average global temperatures to decrease by 0.4β0.7Β Β°C (0.72β1.26Β Β°F). This resulted in major food shortages across the Northern Hemisphere.
Evidence suggests that the anomaly was predominantly a volcanic winter event caused by the massive 1815 eruption of Mount Tambora in April in the Dutch East Indies (now Indonesia). This eruption was the largest eruption in at least 1,300 years (after the hypothesized eruption causing the extreme weather events of 535β536), and perhaps exacerbated by the 1814 eruption of Mayon in the Philippines.
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- "Year Without a Summer" | 2020-02-24 | 295 Upvotes 131 Comments
- "The Year Without a Summer" | 2018-11-17 | 14 Upvotes 1 Comments
π 2022 Oder Environmental Disaster
The 2022 Oder environmental disaster is a mass die-off of fish, beavers and other wildlife in the Oder river in Poland and Germany, causing a health and environmental crisis in large parts of the country and subsequently a political scandal.
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- "2022 Oder Environmental Disaster" | 2022-08-13 | 215 Upvotes 43 Comments
π One Laptop per Child
One Laptop per Child (OLPC) was a non-profit initiative established with the goal of transforming education for children around the world; this goal was to be achieved by creating and distributing educational devices for the developing world, and by creating software and content for those devices.
The goal was to transform education, by enabling children in low-income countries to have access to content, media and computer-programming environments. When the program launched, the typical retail price for a laptop was considerably in excess of $1,000 (US), so achieving this objective required bringing a low-cost machine to production. This became the OLPC XO Laptop, a low-cost and low-power laptop computer designed by Yves BΓ©har. The project was originally funded by member organizations such as AMD, eBay, Google, Marvell Technology Group, News Corporation, Nortel. Chi Mei Corporation, Red Hat, and Quanta provided in-kind support.
The OLPC project was the subject of much discussion. It was praised for pioneering low-cost, low-power laptops and inspiring later variants such as Eee PCs and Chromebooks; for assuring consensus at ministerial level in many countries that computer literacy is a mainstream part of education; for creating interfaces that worked without literacy in any language, and particularly without literacy in English. It was criticized from many sides regarding its US-centric focus ignoring bigger problems, high total costs, low focus on maintainability and training and its limited success. In 2014, after disappointing sales, the Foundation shut down.
The OLPC project is critically reviewed in a 2019 MIT Press book titled The Charisma Machine: The Life, Death, and Legacy of One Laptop per Child.
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- "One Laptop per Child" | 2024-08-26 | 20 Upvotes 21 Comments
- "One Laptop per Child" | 2021-07-12 | 22 Upvotes 12 Comments
π The Great Emu War
The Emu War, also known as the Great Emu War, was a nuisance wildlife management military operation undertaken in Australia over the latter part of 1932 to address public concern over the number of emus said to be running amok in the Campion district of Western Australia. The unsuccessful attempts to curb the population of emus, a large flightless bird indigenous to Australia, employed soldiers armed with Lewis gunsβleading the media to adopt the name "Emu War" when referring to the incident. While a number of the birds were killed, the emu population persisted and continued to cause crop destruction.
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- "Emu War" | 2024-01-15 | 16 Upvotes 7 Comments
- "The Great Emu War" | 2014-11-09 | 15 Upvotes 3 Comments
π One-Way Speed of Light
When using the term 'the speed of light' it is sometimes necessary to make the distinction between its one-way speed and its two-way speed. The "one-way" speed of light, from a source to a detector, cannot be measured independently of a convention as to how to synchronize the clocks at the source and the detector. What can however be experimentally measured is the round-trip speed (or "two-way" speed of light) from the source to a mirror (or other method of reflection) and back again to detector. Albert Einstein chose a synchronization convention (see Einstein synchronization) that made the one-way speed equal to the two-way speed. The constancy of the one-way speed in any given inertial frame is the basis of his special theory of relativity, although all experimentally verifiable predictions of this theory do not depend on that convention.
Experiments that attempt to directly probe the one-way speed of light independent of synchronization have been proposed, but none have succeeded in doing so. Those experiments directly establish that synchronization with slow clock-transport is equivalent to Einstein synchronization, which is an important feature of special relativity. However, those experiments cannot directly establish the isotropy of the one-way speed of light since it has been shown that slow clock-transport, the laws of motion, and the way inertial reference frames are defined already involve the assumption of isotropic one-way speeds and thus, are equally conventional. In general, it was shown that these experiments are consistent with anisotropic one-way light speed as long as the two-way light speed is isotropic.
The 'speed of light' in this article refers to the speed of all electromagnetic radiation in vacuum.
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- "One-Way Speed of Light" | 2023-06-24 | 31 Upvotes 7 Comments
π Emirp Primes
An emirp (prime spelled backwards) is a prime number that results in a different prime when its decimal digits are reversed. This definition excludes the related palindromic primes. The term reversible prime is used to mean the same as emirp, but may also, ambiguously, include the palindromic primes.
The sequence of emirps begins 13, 17, 31, 37, 71, 73, 79, 97, 107, 113, 149, 157, 167, 179, 199, 311, 337, 347, 359, 389, 701, 709, 733, 739, 743, 751, 761, 769, 907, 937, 941, 953, 967, 971, 983, 991, ... (sequence A006567 in the OEIS).
All non-palindromic permutable primes are emirps.
As of NovemberΒ 2009, the largest known emirp is 1010006+941992101Γ104999+1, found by Jens Kruse Andersen in October 2007.
The term 'emirpimes' (singular) is used also in places to treat semiprimes in a similar way. That is, an emirpimes is a semiprime that is also a (distinct) semiprime upon reversing its digits.
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- "Emirp Primes" | 2019-05-02 | 27 Upvotes 14 Comments
π Karmarkar's algorithm β Patent controversy β can mathematics be patented?
Karmarkar's algorithm is an algorithm introduced by Narendra Karmarkar in 1984 for solving linear programming problems. It was the first reasonably efficient algorithm that solves these problems in polynomial time. The ellipsoid method is also polynomial time but proved to be inefficient in practice.
Denoting as the number of variables and as the number of bits of input to the algorithm, Karmarkar's algorithm requires operations on -digit numbers, as compared to such operations for the ellipsoid algorithm. The runtime of Karmarkar's algorithm is thus
using FFT-based multiplication (see Big O notation).
Karmarkar's algorithm falls within the class of interior-point methods: the current guess for the solution does not follow the boundary of the feasible set as in the simplex method, but moves through the interior of the feasible region, improving the approximation of the optimal solution by a definite fraction with every iteration and converging to an optimal solution with rational data.
π Ray Kurzweil 2019 Predictions
American author, inventor and futurist Raymond Kurzweil has become well known for his predictions about artificial intelligence and the human species, mainly concerning the technological singularity. He predicts that Artificial Intelligence would outsmart the human brain in computational capabilities by mid-21st century. His first book, The Age of Intelligent Machines, published in 1990, put forth his theories on the results of the increasing use of technology and predicted the explosive growth in the internet, among other predictions. Later works, 1999's The Age of Spiritual Machines and 2005's The Singularity is Near outlined other theories including the rise of clouds of nano-robots (nanobots) called foglets and the development of Human Body 2.0 and 3.0, whereby nanotechnology is incorporated into many internal organs.
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- "Ray Kurzweil 2019 Predictions" | 2019-01-02 | 60 Upvotes 88 Comments
π IKEA Effect
The IKEA effect is a cognitive bias in which consumers place a disproportionately high value on products they partially created. The name derives from the name of Swedish manufacturer and furniture retailer IKEA, which sells many furniture products that require assembly.
The IKEA effect has been described as follows: "The price is low for IKEA products largely because they take labor out of the equation. With a Phillips screwdriver, an Allen wrench and rubber mallet, IKEA customers can very literally build an entire home's worth of furniture on a very tight budget. But what happens when they do?" They "fall in love with their IKEA creations. Even when there are parts missing and the items are incorrectly built, customers in the IKEA study still loved the fruits of their labors."
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- "IKEA Effect" | 2021-01-18 | 13 Upvotes 1 Comments
- "IKEA Effect" | 2017-12-30 | 256 Upvotes 118 Comments
π Entropy and Life
Research concerning the relationship between the thermodynamic quantity entropy and the evolution of life began around the turn of the 20th century. In 1910, American historian Henry Adams printed and distributed to university libraries and history professors the small volume A Letter to American Teachers of History proposing a theory of history based on the second law of thermodynamics and on the principle of entropy.
The 1944 book What is Life? by Nobel-laureate physicist Erwin SchrΓΆdinger stimulated further research in the field. In his book, SchrΓΆdinger originally stated that life feeds on negative entropy, or negentropy as it is sometimes called, but in a later edition corrected himself in response to complaints and stated that the true source is free energy. More recent work has restricted the discussion to Gibbs free energy because biological processes on Earth normally occur at a constant temperature and pressure, such as in the atmosphere or at the bottom of the ocean, but not across both over short periods of time for individual organisms.
Ideas about the relationship between entropy and living organisms have inspired hypotheses and speculations in many contexts, including psychology, information theory, the origin of life, and the possibility of extraterrestrial life.
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- "Entropy and Life" | 2020-04-12 | 144 Upvotes 61 Comments