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π Kardashev Scale
The Kardashev scale is a method of measuring a civilization's level of technological advancement based on the amount of energy they are able to use. The measure was proposed by Soviet astronomer Nikolai Kardashev in 1964. The scale has three designated categories:
- A TypeΒ I civilization, also called a planetary civilizationβcan use and store all of the energy available on its planet.
- A TypeΒ II civilization, also called a stellar civilizationβcan use and control energy at the scale of its stellar system.
- A TypeΒ III civilization, also called a galactic civilizationβcan control energy at the scale of its entire host galaxy.
Discussed on
- "Kardashev Scale" | 2024-05-11 | 34 Upvotes 28 Comments
- "Kardashev Scale" | 2021-10-13 | 14 Upvotes 1 Comments
- "Kardashev Scale" | 2019-08-03 | 74 Upvotes 31 Comments
- "Kardashev scale" | 2011-02-05 | 72 Upvotes 15 Comments
π Tell HN: Perseids: "Last Chance" for Best Meteor Viewing Tonight
The Perseids are a prolific meteor shower associated with the comet SwiftβTuttle. The meteors are called the Perseids because the point from which they appear to hail (called the radiant) lies in the constellation Perseus.
Discussed on
- "Tell HN: Perseids: "Last Chance" for Best Meteor Viewing Tonight" | 2009-08-12 | 20 Upvotes 13 Comments
π Atash Behram β Types of Fire
An Atash Behram (Fire of Victory) is the highest grade of fire that can be placed in a Zoroastrian fire temple as an eternal flame. The other two lower graded fires are Atash Adaran and below Adaran is the Atash Dadgah; these three grades signify the degree of reverence and dignity these are held in. The establishment and consecration of the Atash Behram fire is the most elaborate of all the grades of fire. It involves the gathering of 16 different types of fire, including fire by lightning (i.e. gathering up any branch of tree ignited by a lightning strike), fire from a cremation pyre, fire from trades where a furnace is operated, and fires from the hearths as is also the case for the Atash Adaran. Each of the 16 fires is then subject to a purification ritual before it joins the others. A large team of priests are required for the purification and consecration ceremonies, which can take up to a year to complete.
The religious significance of gathering purifying and consecrating several fires is to purify and return to Ahura Mazda His first pure creation in its pristine form, to become a focus of worship and His eternal pure symbol, never allowed to go out. The sacred fire at Udvada Atash Behram, for example, kindled in 721 CE in Sanjan, burns continually to this day, now in Udvada since 1741, and housed in a magnificent Persian style temple building since 1742.
Discussed on
- "Atash Behram β Types of Fire" | 2024-06-04 | 98 Upvotes 20 Comments
π James while John had had had ... had had had a better effect on the teacher
"James while John had had had had had had had had had had had a better effect on the teacher" is an English sentence used to demonstrate lexical ambiguity and the necessity of punctuation, which serves as a substitute for the intonation,stress, and pauses found in speech. In human information processing research, the sentence has been used to show how readers depend on punctuation to give sentences meaning, especially in the context of scanning across lines of text. The sentence is sometimes presented as a puzzle, where the solver must add the punctuation.
It refers to two students, James and John, required by an English test to describe a man who had suffered from a cold in the past. John writes "The man had a cold", which the teacher marks incorrect, while James writes the correct "The man had had a cold". Since James's answer was right, it had had a better effect on the teacher.
The sentence is much easier to understand with added punctuation and emphasis:
James, while John had had "had", had had "had had"; "had had" had had a better effect on the teacher.
In each of the five "had had" word pairs in the above sentence, the first of the pair is in the past perfect form. The italicized instances denote emphasis of intonation, focusing on the differences in the students' answers, then finally identifying the correct one.
Discussed on
- "James while John had had had ... had had had a better effect on the teacher" | 2013-03-03 | 114 Upvotes 74 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 Edgelord
An edgelord is someone on the Internet who tries to impress or shock by posting edgy opinions such as nihilism or extremist views.
The term is a portmanteau derived from "edgy" and "shitlord" β a person who "basks in the bitterness and misery of others".
Merriam-Webster gave the following example:
We decided to watch It's A Wonderful Life and my dad said, βEvery year I wait for Jimmy Stewart to jump off that bridge but he never does itβ - merry Xmas from the original edgelord.
Edgelords were characterised by author Rachel Monroe in her account of criminal behaviour, Savage Appetites:
...internet cynics lumped the online Nazis together with the serial killer fetishists and the dumbest goths and dismissed them all as edgelords: kids who tried to be scary online. I thought of most of these edgelords as basement-dwellers, pale faces lit by the glow of their computer screen, puffing themselves up with nihilism. An edgelord was a scrawny guy with a LARP-y vibe, possibly wearing a cloak, dreaming of omnipotence. Or a girl with excessive eyeliner and lots of Tumblr posts about self-harm. The disturbing content posted by edgelords was undermined by its predictability...
It is frequently associated with the forum site 4chan.
Discussed on
- "Edgelord" | 2023-07-22 | 17 Upvotes 1 Comments
π Sequoyah β Inventor of the Cherokee Script
Sequoyah (αααα― Ssiquoya, as he signed his name, or ααα― Se-quo-ya, as is often spelled in Cherokee; named in English George Gist or George Guess) (c.1770β1843), was a Native American polymath of the Cherokee Nation. In 1821 he completed his independent creation of a Cherokee syllabary, making reading and writing in Cherokee possible. This was one of the very few times in recorded history that a member of a pre-literate people created an original, effective writing system (another example being Shong Lue Yang). After seeing its worth, the people of the Cherokee Nation rapidly began to use his syllabary and officially adopted it in 1825. Their literacy rate quickly surpassed that of surrounding European-American settlers.
Discussed on
- "Sequoyah β Inventor of the Cherokee Script" | 2019-12-08 | 68 Upvotes 16 Comments
π Ramanujan's Lost Notebook
Ramanujan's lost notebook is the manuscript in which the Indian mathematician Srinivasa Ramanujan recorded the mathematical discoveries of the last year (1919β1920) of his life. Its whereabouts were unknown to all but a few mathematicians until it was rediscovered by George Andrews in 1976, in a box of effects of G. N. Watson stored at the Wren Library at Trinity College, Cambridge. The "notebook" is not a book, but consists of loose and unordered sheets of paper described as "more than one hundred pages written on 138 sides in Ramanujan's distinctive handwriting. The sheets contained over six hundred mathematical formulas listed consecutively without proofs."
George Andrews and Bruce C. BerndtΒ (2005, 2009, 2012, 2013, 2018) have published several books in which they give proofs for Ramanujan's formulas included in the notebook. Berndt says of the notebook's discovery: "The discovery of this 'Lost Notebook' caused roughly as much stir in the mathematical world as the discovery of Beethovenβs tenth symphony would cause in the musical world."
Discussed on
- "Ramanujan's Lost Notebook" | 2024-04-15 | 306 Upvotes 94 Comments
π Lindy Effect
The Lindy effect is a theory that the future life expectancy of some non-perishable things like a technology or an idea is proportional to their current age, so that every additional period of survival implies a longer remaining life expectancy. Where the Lindy effect applies, mortality rate decreases with time.
Discussed on
- "Lindy Effect" | 2023-05-02 | 22 Upvotes 1 Comments
- "Lindy effect" | 2017-07-30 | 225 Upvotes 64 Comments
π Phonautograph
The phonautograph is the earliest known device for recording sound. Previously, tracings had been obtained of the sound-producing vibratory motions of tuning forks and other objects by physical contact with them, but not of actual sound waves as they propagated through air or other media. Invented by Frenchman Γdouard-LΓ©on Scott de Martinville, it was patented on March 25, 1857. It transcribed sound waves as undulations or other deviations in a line traced on smoke-blackened paper or glass. Intended solely as a laboratory instrument for the study of acoustics, it could be used to visually study and measure the amplitude envelopes and waveforms of speech and other sounds, or to determine the frequency of a given musical pitch by comparison with a simultaneously recorded reference frequency.
Apparently, it did not occur to anyone before the 1870s that the recordings, called phonautograms, contained enough information about the sound that they could, in theory, be used to recreate it. Because the phonautogram tracing was an insubstantial two-dimensional line, direct physical playback was impossible in any case.
Several phonautograms recorded before 1861 were successfully played as sound in 2008 by optically scanning them and using a computer to process the scans into digital audio files.