Random Articles (Page 186)
Have a deep view into what people are curious about.
π Our world is turning into the one depicted in Ray Bradbury's "The Murderer"
"The Murderer" (1953) is a short story by Ray Bradbury, published in his collection The Golden Apples of the Sun.
Discussed on
- "Our world is turning into the one depicted in Ray Bradbury's "The Murderer"" | 2011-09-26 | 10 Upvotes 2 Comments
π Mummy Brown
Mummy brown, also known as Egyptian brown or Caput Mortuum,:β254β is a rich brown bituminous pigment with good transparency, sitting between burnt umber and raw umber in tint. The pigment was made from the flesh of mummies mixed with white pitch and myrrh. Mummy brown was extremely popular from the mid-eighteenth to the nineteenth centuries. However, fresh supplies of mummies diminished, and artists were less satisfied with the pigment's permanency and finish. By 1915, demand had significantly declined. Suppliers ceased to offer it by the middle of the twentieth century.:β82β
Mummy brown was one of the favourite colours of the Pre-Raphaelites. It was used by many artists, including Eugene Delacroix, William Beechey, Edward Burne-Jones, Lawrence Alma-Tadema, and Martin Drolling.
Discussed on
- "Mummy Brown" | 2024-05-16 | 40 Upvotes 16 Comments
π Foucault pendulum
The Foucault pendulum or Foucault's pendulum is a simple device named after French physicist LΓ©on Foucault and conceived as an experiment to demonstrate the Earth's rotation. The pendulum was introduced in 1851 and was the first experiment to give simple, direct evidence of the earth's rotation. Foucault pendulums today are popular displays in science museums and universities.
Discussed on
- "Foucault pendulum" | 2020-04-27 | 69 Upvotes 33 Comments
π Haversine Formula
The haversine formula determines the great-circle distance between two points on a sphere given their longitudes and latitudes. Important in navigation, it is a special case of a more general formula in spherical trigonometry, the law of haversines, that relates the sides and angles of spherical triangles.
The first table of haversines in English was published by James Andrew in 1805, but Florian Cajori credits an earlier use by JosΓ© de Mendoza y RΓos in 1801. The term haversine was coined in 1835 by James Inman.
These names follow from the fact that they are customarily written in terms of the haversine function, given by hav(ΞΈ) = sin2(ΞΈ/2). The formulas could equally be written in terms of any multiple of the haversine, such as the older versine function (twice the haversine). Prior to the advent of computers, the elimination of division and multiplication by factors of two proved convenient enough that tables of haversine values and logarithms were included in nineteenth and early twentieth century navigation and trigonometric texts. These days, the haversine form is also convenient in that it has no coefficient in front of the sin2 function.
Discussed on
- "Haversine Formula" | 2019-04-12 | 73 Upvotes 31 Comments
π Relativistic Quantum Chemistry
Relativistic quantum chemistry combines relativistic mechanics with quantum chemistry to explain elemental properties and structure, especially for the heavier elements of the periodic table. A prominent example of such an explanation is the color of gold: due to relativistic effects, it is not silvery like most other metals.
The term relativistic effects was developed in light of the history of quantum mechanics. Initially quantum mechanics was developed without considering the theory of relativity. Relativistic effects are those discrepancies between values calculated by models that consider and that do not consider relativity. Relativistic effects are important for the heavier elements with high atomic numbers. In the most common layout of the periodic table, these elements are shown in the lower area. Examples are the lanthanides and actinides.
Relativistic effects in chemistry can be considered to be perturbations, or small corrections, to the non-relativistic theory of chemistry, which is developed from the solutions of the SchrΓΆdinger equation. These corrections affect the electrons differently depending on the electron speed relative to the speed of light. Relativistic effects are more prominent in heavy elements because only in these elements do electrons attain sufficient speeds for the elements to have properties that differ from what non-relativistic chemistry predicts.
Discussed on
- "Relativistic Quantum Chemistry" | 2019-10-12 | 70 Upvotes 5 Comments
π Axial twist theory
The axial twist theory (a.k.a. axial twist hypothesis) is a proposed scientific theory to explain a range of unusual aspects of the body plan of vertebrates (including humans). It states that the rostral part of the head is "turned around" regarding the rest of the body. This end-part consists of the face (eyes, nose, and mouth) as well as part of the brain (cerebrum and thalamus). According to the theory, the vertebrate body has a left-handed chirality.
The axial twist theory competes with a number of other proposals that focus on more limited, specific aspects, most of which explain contralateral forebrain organization, the phenomenon that the left side of the brain mainly controls the right side of the body and vice versa. None of the proposed theories explaining this phenomenon, including axial twist theory, have gained general recognition. The genetic basis underlying the proposed developmental twist is not yet understood.
The axial twist theory would explain various anatomical phenomena, and addresses how and when the proposed twist between the end of the head and the rest of the body develops. It also addresses the possible evolutionary history. One prediction of the theory was the aurofacial asymmetry, which was then found empirically, albeit by one of the authors of the original theory.
Phenomena the theory can explain include:
- Contralateral organization of the brain
- Left-sided orientation of the heart
- Asymmetric position of the gastrointestinal tract, the liver, and the pancreas
- Optic chiasm
- Chiasm of the trochlear nerve
- Non-crossed olfactory tract
- Aurofacial asymmetry
- Yakovlevian torque
- Asymmetry of the thoracal vertebra
According to the axial twist developmental model, the anterior part of the head turns against the rest of the body, except for the inner organs. Due to this twist, the forebrain and face are turned around such that left and right, but also anterior and posterior are flipped in the adult vertebrate.
Discussed on
- "Axial twist theory" | 2025-09-07 | 178 Upvotes 45 Comments
π Exercises in Style
Exercises in Style (French: Exercices de style), written by Raymond Queneau, is a collection of 99 retellings of the same story, each in a different style. In each, the narrator gets on the "S" bus (now no. 84), witnesses an altercation between a man (a zazou) with a long neck and funny hat and another passenger, and then sees the same person two hours later at the Gare St-Lazare getting advice on adding a button to his overcoat. The literary variations recall the famous 33rd chapter of the 1512 rhetorical guide by Desiderius Erasmus, Copia: Foundations of the Abundant Style.
Discussed on
- "Exercises in Style" | 2014-03-22 | 20 Upvotes 7 Comments
π List of countries by tax revenue to GDP ratio
This article lists countries alphabetically, with total tax revenue as a percentage of gross domestic product (GDP) for the listed countries. The tax percentage for each country listed in the source has been added to the chart.
Discussed on
- "List of countries by tax revenue to GDP ratio" | 2022-10-03 | 13 Upvotes 7 Comments
π Hedges vs. Obama
Hedges v. Obama was a lawsuit filed in January 2012 against the Obama administration and members of the U.S. Congress by a group including former New York Times reporter Christopher Hedges, challenging the National Defense Authorization Act for Fiscal Year 2012 (NDAA). The legislation permitted the U.S. government to indefinitely detain people "who are part of or substantially support Al Qaeda, the Taliban or associated forces engaged in hostilities against the United States". The plaintiffs contended that Section 1021(b)(2) of the law allows for detention of citizens and permanent residents taken into custody in the U.S. on "suspicion of providing substantial support" to groups engaged in hostilities against the U.S. such as al-Qaeda and the Taliban respectively that the NDAA arms the U.S. military with the ability to imprison indefinitely journalists, activists and human-rights workers based on vague allegations.
A federal court in New York issued a permanent injunction blocking the indefinite detention powers of the NDAA but the injunction was stayed by the Second Circuit Court of Appeals pending appeal by the Obama Administration. On July 17, 2013, the Second Circuit Court of Appeals overturned the district court's permanent injunction blocking the indefinite detention powers of the NDAA because the plaintiffs lacked legal standing to challenge the indefinite detention powers of the NDAA. The Supreme Court declined to hear the case on April 28, 2014, leaving the Second Circuit decision intact.
Discussed on
- "Hedges vs. Obama" | 2021-10-30 | 17 Upvotes 8 Comments
π Self-Replicating Machine
A self-replicating machine is a type of autonomous robot that is capable of reproducing itself autonomously using raw materials found in the environment, thus exhibiting self-replication in a way analogous to that found in nature. The concept of self-replicating machines has been advanced and examined by Homer Jacobson, Edward F. Moore, Freeman Dyson, John von Neumann, Konrad Zuse and in more recent times by K. Eric Drexler in his book on nanotechnology, Engines of Creation (coining the term clanking replicator for such machines) and by Robert Freitas and Ralph Merkle in their review Kinematic Self-Replicating Machines which provided the first comprehensive analysis of the entire replicator design space. The future development of such technology is an integral part of several plans involving the mining of moons and asteroid belts for ore and other materials, the creation of lunar factories, and even the construction of solar power satellites in space. The von Neumann probe is one theoretical example of such a machine. Von Neumann also worked on what he called the universal constructor, a self-replicating machine that would be able to evolve and which he formalized in a cellular automata environment. Notably, Von Neumann's Self-Reproducing Automata scheme posited that open-ended evolution requires inherited information to be copied and passed to offspring separately from the self-replicating machine, an insight that preceded the discovery of the structure of the DNA molecule by Watson and Crick and how it is separately translated and replicated in the cell.
A self-replicating machine is an artificial self-replicating system that relies on conventional large-scale technology and automation. Although suggested earlier than in the late 1940's by Von Neumann, no self-replicating machine has been seen until today. Certain idiosyncratic terms are occasionally found in the literature. For example, the term clanking replicator was once used by Drexler to distinguish macroscale replicating systems from the microscopic nanorobots or "assemblers" that nanotechnology may make possible, but the term is informal and is rarely used by others in popular or technical discussions. Replicators have also been called "von Neumann machines" after John von Neumann, who first rigorously studied the idea. However, the term "von Neumann machine" is less specific and also refers to a completely unrelated computer architecture that von Neumann proposed and so its use is discouraged where accuracy is important. Von Neumann himself used the term universal constructor to describe such self-replicating machines.
Historians of machine tools, even before the numerical control era, sometimes figuratively said that machine tools were a unique class of machines because they have the ability to "reproduce themselves" by copying all of their parts. Implicit in these discussions is that a human would direct the cutting processes (later planning and programming the machines), and would then assemble the parts. The same is true for RepRaps, which are another class of machines sometimes mentioned in reference to such non-autonomous "self-replication". In contrast, machines that are truly autonomously self-replicating (like biological machines) are the main subject discussed here.