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π Two capacitor paradox
The two capacitor paradox or capacitor paradox is a paradox, or counterintuitive thought experiment, in electric circuit theory. The thought experiment is usually described as follows: Two identical capacitors are connected in parallel with an open switch between them. One of the capacitors is charged with a voltage of , the other is uncharged. When the switch is closed, some of the charge on the first capacitor flows into the second, reducing the voltage on the first and increasing the voltage on the second. When a steady state is reached and the current goes to zero, the voltage on the two capacitors must be equal since they are connected together. Since they both have the same capacitance the charge will be divided equally between the capacitors so each capacitor will have a charge of and a voltage of . At the beginning of the experiment the total initial energy in the circuit is the energy stored in the charged capacitor:
- .
At the end of the experiment the final energy is equal to the sum of the energy in the two capacitors
Thus the final energy is equal to half of the initial energy . Where did the other half of the initial energy go?
Discussed on
- "Two capacitor paradox" | 2020-05-25 | 438 Upvotes 169 Comments
π Pelorus Jack
Pelorus Jack (fl. 1888Β β April 1912) was a Risso's dolphin that was famous for meeting and escorting ships through a stretch of water in Cook Strait, New Zealand, between 1888 and 1912. Pelorus Jack was usually spotted in Admiralty Bay between Cape Francis and Collinet Point, near French Pass, a notoriously dangerous channel used by ships travelling between Wellington and Nelson.
Pelorus Jack was shot at from a passing ship, and was later protected by a 1904 New Zealand law.
Discussed on
- "Pelorus Jack" | 2020-05-25 | 187 Upvotes 30 Comments
π The Great Plague of Marseille
The Great Plague of Marseille was the last major outbreak of bubonic plague in western Europe. Arriving in Marseille, France in 1720, the disease killed a total of 100,000 people: 50,000 in the city during the next two years and another 50,000 to the north in surrounding provinces and towns.
While economic activity took only a few years to recover, as trade expanded to the West Indies and Latin America, it was not until 1765 that the population returned to its pre-1720 level.
Discussed on
- "The Great Plague of Marseille" | 2020-05-24 | 29 Upvotes 14 Comments
π Pantai Remis Landslide
The Pantai Remis landslide was a rock fall and flood that occurred on 21 October 1993, near Pantai Remis in Perak, Malaysia. The landslide took place in an abandoned open cast tin mine (in a region of the state well known for its tin mining industry) close to the Strait of Malacca. Video footage shows the rapid collapse of the working face closest the sea, allowing complete flooding of the mine and forming a new cove measuring approximately 0.5Β km2 (0.19Β sqΒ mi).
Discussed on
- "Pantai Remis Landslide" | 2020-05-24 | 41 Upvotes 24 Comments
π Norton Commander
Norton Commander (NC) is a discontinued prototypical orthodox file manager (OFM), written by John Socha and released by Peter Norton Computing (later acquired in 1990 by the Symantec corporation). NC provides a text-based user interface for managing files on top of MS-DOS. It was officially produced between 1986 and 1998. The last MS-DOS version of Norton Commander, 5.51, was released on July 1, 1998.
A related product, Norton Desktop, a graphical shell for MS-DOS and Windows, succeeded Norton Commander. It came in two variants, Norton Desktop for DOS and Norton Desktop for Windows.
Discussed on
- "Norton Commander" | 2020-05-22 | 35 Upvotes 51 Comments
π Hypothetical types of biochemistry
Hypothetical types of biochemistry are forms of biochemistry speculated to be scientifically viable but not proven to exist at this time. The kinds of living organisms currently known on Earth all use carbon compounds for basic structural and metabolic functions, water as a solvent, and DNA or RNA to define and control their form. If life exists on other planets or moons, it may be chemically similar; it is also possible that there are organisms with quite different chemistriesβfor instance, involving other classes of carbon compounds, compounds of another element, or another solvent in place of water.
The possibility of life-forms being based on "alternative" biochemistries is the topic of an ongoing scientific discussion, informed by what is known about extraterrestrial environments and about the chemical behaviour of various elements and compounds. It is of interest in synthetic biology and is also a common subject in science fiction.
The element silicon has been much discussed as a hypothetical alternative to carbon. Silicon is in the same group as carbon on the periodic table and, like carbon, it is tetravalent. Hypothetical alternatives to water include ammonia, which, like water, is a polar molecule, and cosmically abundant; and non-polar hydrocarbon solvents such as methane and ethane, which are known to exist in liquid form on the surface of Titan.
Discussed on
- "Hypothetical Types of Biochemistry" | 2020-05-21 | 49 Upvotes 7 Comments
- "Hypothetical types of biochemistry" | 2015-03-25 | 42 Upvotes 2 Comments
π McLibel Case
McDonald's Corporation v Steel & Morris [1997] EWHC QB 366, known as "the McLibel case", was an English lawsuit for libel filed by McDonald's Corporation against environmental activists Helen Steel and David Morris (often referred to as "The McLibel Two") over a factsheet critical of the company. Each of two hearings in English courts found some of the leaflet's contested claims to be libellous and others to be true.
The original case lasted nearly ten years which, according to the BBC, made it the longest-running libel case in English history. McDonald's announced it did not plan to collect the Β£40,000 it was awarded by the courts. Following the decision, the European Court of Human Rights (ECHR) ruled in Steel & Morris v United Kingdom the pair had been denied a fair trial, in breach of Article 6 of the European Convention on Human Rights (right to a fair trial) and their conduct should have been protected by Article 10 of the Convention, which protects the right to freedom of expression. The court awarded a judgement of Β£57,000 against the UK government. McDonald's itself was not involved in, or a party to, this action, as applications to the ECHR are independent cases filed against the relevant state.
Franny Armstrong and Ken Loach made a documentary film, McLibel, about the case.
Discussed on
- "McLibel Case" | 2020-05-21 | 69 Upvotes 26 Comments
π Polywater
Polywater was a hypothesized polymerized form of water that was the subject of much scientific controversy during the late 1960s. By 1969 the popular press had taken notice and sparked fears of a "polywater gap" in the US.
Increased press attention also brought with it increased scientific attention, and as early as 1970 doubts about its authenticity were being circulated. By 1973 it was found to be illusory, being just water with any number of common organic compounds contaminating it.
Today, polywater is best known as an example of pathological science.
Discussed on
- "Polywater" | 2020-05-20 | 49 Upvotes 1 Comments
π Covid-19 Vaccine Candidates
A COVID-19 vaccine is a hypothetical vaccine against coronavirus disease 2019 (COVIDβ19). Although no vaccine has completed clinical trials, there are multiple attempts in progress to develop such a vaccine. In February 2020, the World Health Organization (WHO) said it did not expect a vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative virus, to become available in less than 18 months. The Coalition for Epidemic Preparedness Innovations (CEPI)Β β which is organizing a US$2 billion worldwide fund for rapid investment and development of vaccine candidatesΒ β indicated in April that a vaccine may be available under emergency use protocols in less than 12 months or by early 2021. On 4Β May 2020, the WHO organized a telethon to raise US$8 billion from forty countries to support rapid development of vaccines to prevent COVID-19 infections, also announcing deployment of an international "Solidarity trial" for simultaneous evaluation of several vaccine candidates reaching Phase II-III clinical trials.
By May, 159 vaccine candidates were in development, with five having been initiated in PhaseΒ IβII safety and efficacy studies in human subjects, and seven in PhaseΒ I trials.
Discussed on
- "Covid-19 Vaccine Candidates" | 2020-05-20 | 53 Upvotes 63 Comments
π Censorship by Google
Google and its subsidiary companies, such as YouTube, have removed or omitted information from its services to comply with its company policies, legal demands, and government censorship laws. Google's censorship varies between countries and their regulations, and ranges from advertisements to speeches. Over the years, the search engine's censorship policies and targets have also differed, and have been the source of internet censorship debates.
Numerous governments have asked Google to censor what they publish. In 2012, Google ruled in favor of more than half of the requests they received via court orders and phone calls. This did not include China and Iran who had blocked their site entirely.
Discussed on
- "Censorship by Google" | 2020-05-19 | 59 Upvotes 17 Comments