Have a deep view into what people are curious about.

🔗 France 🔗 Law

Droit de suite (French for "right to follow") or Artist's Resale Right (ARR) is a right granted to artists or their heirs, in some jurisdictions, to receive a fee on the resale of their works of art. This should be contrasted with policies such as the American first-sale doctrine, where artists do not have the right to control or profit from subsequent sales.

🔗 Physics 🔗 Philosophy 🔗 Philosophy/Metaphysics

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 (1844–1906), 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.

🔗 Medicine 🔗 Iran 🔗 History of Science 🔗 Middle Ages 🔗 Islam 🔗 Middle Ages/History 🔗 Turkey

A bimaristan (Persian: بيمارستان‎, romanized: bīmārestān; Arabic: بِيْمَارِسْتَان‎, romanized: bīmāristān), also known as dar al-shifa (also darüşşifa in Turkish) or simply maristan, is a hospital in the historic Islamic world.

🔗 United States 🔗 Middle Ages 🔗 Middle Ages/History 🔗 Archaeology 🔗 Indigenous peoples of North America 🔗 Cities 🔗 World Heritage Sites 🔗 Illinois 🔗 National Register of Historic Places 🔗 Historic sites 🔗 Protected areas 🔗 St. Louis

The Cahokia Mounds (also simply known as Cahokia) (11 MS 2) is the site of a Native American city (which existed c. 1050–1350 CE) directly across the Mississippi River from present-day St. Louis. The state archaeology park lies in south-western Illinois between East St. Louis and Collinsville. The park covers 2,200 acres (890 ha), or about 3.5 square miles (9 km²), and contains about 80 manmade mounds, but the ancient city was much larger. At its apex around 1100 CE, the city covered about 6 square miles (16 km²), included about 120 earthworks in a wide range of sizes, shapes, and functions, and had a population of between 15,000 and 20,000 people.

Cahokia was the largest and most influential urban settlement of the Mississippian culture, which developed advanced societies across much of what is now the Central and the Southeastern United States, beginning around 1000 CE. Today, the Cahokia Mounds are considered to be the largest and most complex archaeological site north of the great pre-Columbian cities in Mexico.

The city's original name is unknown. The mounds were later named after the Cahokia tribe, a historic Illiniwek people living in the area when the first French explorers arrived in the 17th century. As this was centuries after Cahokia was abandoned by its original inhabitants, the Cahokia tribe was not necessarily descended from the earlier Mississippian-era people. Most likely, multiple indigenous ethnic groups settled in the Cahokia Mounds area during the time of the city's apex.

Cahokia Mounds is a National Historic Landmark and a designated site for state protection. It is also one of the 26 UNESCO World Heritage Sites within the United States. The largest pre-Columbian earthen construction in the Americas north of Mexico, the site is open to the public and administered by the Illinois Historic Preservation Division and supported by the Cahokia Mounds Museum Society. In celebration of the 2018 Illinois state bicentennial, the Cahokia Mounds were selected as one of the Illinois 200 Great Places by the American Institute of Architects Illinois component (AIA Illinois). It was recognized by USA Today Travel magazine, as one of the selections for 'Illinois 25 Must See Places'.

🔗 Biography 🔗 Comedy 🔗 Biography/arts and entertainment 🔗 Japan 🔗 Japan/Biography 🔗 Japan/Owarai 🔗 Japan/Gaijin tarento

Jason David Danielson (born April 9, 1986), known professionally as Atsugiri Jason (厚切りジェイソン, Atsugiri Jeison, lit. "Thick-sliced Jason"), is an American comedian based in Japan and associated with Watanabe Entertainment. Danielson's comedic narrative is based on his confusion with kanji, ending with the punchline, "Why Japanese people?!"

🔗 Physics 🔗 Chemistry 🔗 Materials

High-entropy alloys (HEAs) are alloys that are formed by mixing equal or relatively large proportions of (usually) five or more elements. Prior to the synthesis of these substances, typical metal alloys comprised one or two major components with smaller amounts of other elements. For example, additional elements can be added to iron to improve its properties, thereby creating an iron-based alloy, but typically in fairly low proportions, such as the proportions of carbon, manganese, and others in various steels. Hence, high-entropy alloys are a novel class of materials. The term "high-entropy alloys" was coined by Taiwanese scientist Jien-Wei Yeh because the entropy increase of mixing is substantially higher when there is a larger number of elements in the mix, and their proportions are more nearly equal. Some alternative names, such as multi-component alloys, compositionally complex alloys and multi-principal-element alloys are also suggested by other researchers. Compositionally complex alloys (CCAs) are an up-and-coming group of materials due to their unique mechanical properties. They have high strength and toughness, the ability to operate at higher temperatures than current alloys, and have superior ductility. Material ductility is important because it quantifies the permanent deformation a material can withstand before failure, a key consideration in designing safe and reliable materials. Due to their enhanced properties, CCAs show promise in extreme environments. An extreme environment presents significant challenges for a material to perform to its intended use within designated safety limits. CCAs can be used in several applications such as aerospace propulsion systems, land-based gas turbines, heat exchangers, and the chemical process industry.

These alloys are currently the focus of significant attention in materials science and engineering because they have potentially desirable properties. Furthermore, research indicates that some HEAs have considerably better strength-to-weight ratios, with a higher degree of fracture resistance, tensile strength, and corrosion and oxidation resistance than conventional alloys. Although HEAs have been studied since the 1980s, research substantially accelerated in the 2010s.

🔗 Aviation 🔗 Aviation/aircraft 🔗 Aviation/rotorcraft

The cyclogyro, or cyclocopter, is an aircraft configuration that uses a horizontal-axis cyclorotor as a rotor wing to provide lift and sometimes also propulsion and control. In principle, the cyclogyro is capable of vertical take off and landing and hovering performance like a helicopter, while potentially benefiting from some of the advantages of a fixed-wing aircraft.

The cyclogyro is distinct from the Flettner airplane which uses a cylindrical wing rotor to harness the Magnus effect.

🔗 Physics 🔗 Physics/relativity

In physics, there is a speculative hypothesis that, if there were a black hole with the same mass, charge and angular momentum as an electron, it would share other properties of the electron. Most notably, Brandon Carter showed in 1968 that the magnetic moment of such an object would match that of an electron. This is interesting because calculations ignoring special relativity and treating the electron as a small rotating sphere of charge give a magnetic moment roughly half the experimental value (see Gyromagnetic ratio).

However, Carter's calculations also show that a would-be black hole with these parameters would be "super-extremal". Thus, unlike a true black hole, this object would display a naked singularity, meaning a singularity in spacetime not hidden behind an event horizon. It would also give rise to closed timelike curves.

Standard quantum electrodynamics (QED), currently the most comprehensive theory of particles, treats the electron as a point particle. There is no evidence that the electron is a black hole (or naked singularity) or not. Furthermore, since the electron is quantum-mechanical in nature, any description purely in terms of general relativity is paradoxical until a better model based on understanding of quantum nature of blackholes and gravitational behaviour of quantum particles is developed by research. Hence, the idea of a black hole electron remains strictly hypothetical.

🔗 Computing 🔗 Computing/Software 🔗 Computing/Free and open-source software 🔗 Plan 9

Plan 9 from Bell Labs is a distributed operating system, originating in the Computing Science Research Center (CSRC) at Bell Labs in the mid-1980s, and building on UNIX concepts first developed there in the late 1960s. The final official release was in early 2015.

Under Plan 9, UNIX's everything is a file metaphor is extended via a pervasive network-centric filesystem, and graphical user interface is assumed as a basis for almost all functionality, though it retains a heavily text-centric ideology.

The name Plan 9 from Bell Labs is a reference to the Ed Wood 1959 cult science fiction Z-movie Plan 9 from Outer Space. The name of the project's mascot is "Glenda, the Plan 9 Bunny". The system continues to be used and developed by operating system researchers and hobbyists.