Have a deep view into what people are curious about.

🔗 Internet culture

Eternal September or the September that never ended is Usenet slang for a period beginning in September 1993, the month that Internet service provider America Online (AOL) began offering Usenet access to its many users, overwhelming the existing culture for online forums.

Before then, Usenet was largely restricted to colleges, universities, and other research institutions. Every September, many incoming students would acquire access to Usenet for the first time, taking time to become accustomed to Usenet's standards of conduct and "netiquette". After a month or so, these new users would either learn to comply with the networks' social norms or tire of using the service.

Whereas the regular September student influx would quickly settle down, the influx of new users from AOL did not end and Usenet's existing culture did not have the capacity to integrate the sheer number of new users. The influx was exacerbated by the aggressive direct mailing campaign by AOL Chief Marketing Officer Jan Brandt, which most notably involved distributing millions of floppy disks and CD-ROMs with free trials of AOL.

Since then the popularity of the Internet has led to a constant stream of new users. Hence, from the point of view of the early Usenet, the influx of new users in September 1993 never ended.

Dave Fischer appears to have coined the term in a January 1994 post to alt.folklore.computers: "It's moot now. September 1993 will go down in net history as the September that never ended."

🔗 Statistics

In statistics, Halton sequences are sequences used to generate points in space for numerical methods such as Monte Carlo simulations. Although these sequences are deterministic, they are of low discrepancy, that is, appear to be random for many purposes. They were first introduced in 1960 and are an example of a quasi-random number sequence. They generalize the one-dimensional van der Corput sequences.

🔗 Internet 🔗 Internet culture 🔗 Business 🔗 Politics 🔗 Sociology

The Streisand effect is a social phenomenon that occurs when an attempt to hide, remove, or censor information has the unintended consequence of further publicizing that information, often via the Internet. It is named after American entertainer Barbra Streisand, whose attempt to suppress photographs of her residence in Malibu, California inadvertently drew further attention to it in 2003.

Attempts to suppress information are often made through cease-and-desist letters, but instead of being suppressed, the information receives extensive publicity, as well as media extensions such as videos and spoof songs, which can be mirrored on the Internet or distributed on file-sharing networks.

The Streisand effect is an example of psychological reactance, wherein once people are aware that some information is being kept from them, they are significantly more motivated to access and spread that information.

🔗 Astronomy

Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE) is a program which utilizes high-altitude balloon instrument package intended to measure the heating of the universe by the first stars and galaxies after the big bang and search for the signal of relic decay or annihilation. In July 2006 a strong residual radio source was found using the radiometer, approximately six times what is predicted by theory. This phenomenon is known as "space roar" and remains an unsolved problem in astrophysics.

ARCADE has been funded by the NASA's Science Mission Directorate under the Astronomy and Physics Research and Analysis Suborbital Investigation program. The program is composed of a team led by Alan Kogut of NASA's Goddard Space Flight Center. ARCADE was launched from NASA's Columbia Scientific Balloon Facility in Palestine, Texas, conducted under the auspices of the Balloon Program Office at Wallops Flight Facility. The balloon flew to an altitude of 120,000 feet (37 km), viewing about 7% of the sky during its observations.

The instrument is designed to detect radiation at centimeter wavelengths. The craft contained seven radiometers which were cooled to 2.7 K (−270.45 °C; −454.81 °F) using liquid helium, with the intent to measure temperature differences as small as 1/1000 of a degree against a background which is only 3 K (−270.15 °C; −454.27 °F). The optics in the instrument package were placed near the top of the dewar flask which cooled them in order to prevent the instruments from seeing the walls of the container, thereby simplifying the processing of the observational data. This design choice necessitated the use of superfluid pumps in order to drench the radiometers in liquid helium. The design also utilized heaters in order to create a cloud of helium gas, in place of using a (relatively warm) window, which also simplified processing of the observational data.

🔗 Africa 🔗 Philosophy 🔗 Philosophy/Anarchism 🔗 Somalia

Xeer (pronounced [ħeːr]) is the traditional legal system of Somalia, and one of the three systems from which formal Somali law draws its inspiration, the others being civil law and Islamic law. It is believed to pre-date Islam, although it was influenced by Islam and retains many of the faith's conservative elements. Under this system, elders, known as the xeer begti serve as mediator judges and help settle court cases, taking precedent and custom into account. Xeer is polycentric in that different groups within Somali society have different interpretations of xeer.

🔗 Philosophy 🔗 Philosophy/Logic 🔗 Philosophy/Contemporary philosophy 🔗 Philosophy/Philosophy of religion 🔗 Christianity 🔗 Christianity/theology 🔗 Military history/European military history

Gödel's ontological proof is a formal argument by the mathematician Kurt Gödel (1906–1978) for the existence of God. The argument is in a line of development that goes back to Anselm of Canterbury (1033–1109). St. Anselm's ontological argument, in its most succinct form, is as follows: "God, by definition, is that for which no greater can be conceived. God exists in the understanding. If God exists in the understanding, we could imagine Him to be greater by existing in reality. Therefore, God must exist." A more elaborate version was given by Gottfried Leibniz (1646–1716); this is the version that Gödel studied and attempted to clarify with his ontological argument.

Gödel left a fourteen-point outline of his philosophical beliefs in his papers. Points relevant to the ontological proof include

4. There are other worlds and rational beings of a different and higher kind.

5. The world in which we live is not the only one in which we shall live or have lived.

13. There is a scientific (exact) philosophy and theology, which deals with concepts of the highest abstractness; and this is also most highly fruitful for science.

14. Religions are, for the most part, bad—but religion is not.

🔗 Mathematics 🔗 Philosophy 🔗 Statistics

Fuzzy logic is a form of many-valued logic in which the truth values of variables may be any real number between 0 and 1 both inclusive. It is employed to handle the concept of partial truth, where the truth value may range between completely true and completely false. By contrast, in Boolean logic, the truth values of variables may only be the integer values 0 or 1.

The term fuzzy logic was introduced with the 1965 proposal of fuzzy set theory by Lotfi Zadeh. Fuzzy logic had, however, been studied since the 1920s, as infinite-valued logic—notably by Łukasiewicz and Tarski.

Fuzzy logic is based on the observation that people make decisions based on imprecise and non-numerical information. Fuzzy models or sets are mathematical means of representing vagueness and imprecise information (hence the term fuzzy). These models have the capability of recognising, representing, manipulating, interpreting, and utilising data and information that are vague and lack certainty.

Fuzzy logic has been applied to many fields, from control theory to artificial intelligence.

🔗 Medicine 🔗 Statistics 🔗 Microbiology 🔗 Game theory

Herd immunity (also called herd effect, community immunity, population immunity, or social immunity) is a form of indirect protection from infectious disease that occurs when a large percentage of a population has become immune to an infection, whether through previous infections or vaccination, thereby providing a measure of protection for individuals who are not immune. In a population in which a large proportion of individuals possess immunity, such people being unlikely to contribute to disease transmission, chains of infection are more likely to be disrupted, which either stops or slows the spread of disease. The greater the proportion of immune individuals in a community, the smaller the probability that non-immune individuals will come into contact with an infectious individual, helping to shield non-immune individuals from infection.

Individuals can become immune by recovering from an earlier infection or through vaccination. Some individuals cannot become immune due to medical reasons, such as an immunodeficiency or immunosuppression, and in this group herd immunity is a crucial method of protection. Once a certain threshold has been reached, herd immunity gradually eliminates a disease from a population. This elimination, if achieved worldwide, may result in the permanent reduction in the number of infections to zero, called eradication. Herd immunity created via vaccination contributed to the eventual eradication of smallpox in 1977 and has contributed to the reduction of the frequencies of other diseases. Herd immunity does not apply to all diseases, just those that are contagious, meaning that they can be transmitted from one individual to another. Tetanus, for example, is infectious but not contagious, so herd immunity does not apply.

The term "herd immunity" was first used in 1923. It was recognized as a naturally occurring phenomenon in the 1930s when it was observed that after a significant number of children had become immune to measles, the number of new infections temporarily decreased, including among susceptible children. Mass vaccination to induce herd immunity has since become common and proved successful in preventing the spread of many infectious diseases. Opposition to vaccination has posed a challenge to herd immunity, allowing preventable diseases to persist in or return to communities that have inadequate vaccination rates.

🔗 Philately 🔗 Netherlands

A postzegelcode is a hand-written method of franking in the Netherlands. It consists of a code containing nine numbers and letters that customers can purchase online from PostNL and write directly on their piece of mail within five days as proof-of-payment in place of a postage stamp.

For mail within the Netherlands the nine letters and numbers are written as a grid of 3x3. For international mail there is fourth additional row that contains P, N, L.

The system was started in 2013. Initially the postzegelcode was more expensive than a stamp because additional handling systems were required. Then for a while the postzegelcode was cheaper. Eventually the tariffs were set to the same price.

In December 2020, 590,000 people sent cards with postzegelcodes.

🔗 Computing 🔗 Mathematics 🔗 Computing/Networking

In mathematics, the Cheeger constant (also Cheeger number or isoperimetric number) of a graph is a numerical measure of whether or not a graph has a "bottleneck". The Cheeger constant as a measure of "bottleneckedness" is of great interest in many areas: for example, constructing well-connected networks of computers, card shuffling. The graph theoretical notion originated after the Cheeger isoperimetric constant of a compact Riemannian manifold.

The Cheeger constant is named after the mathematician Jeff Cheeger.