Portal:Science

The St. Croix macaw (Ara autocthones) or Puerto Rican macaw is an extinct species of macaw whose remains have been found on the Caribbean islands of St. Croix and Puerto Rico. It was described in 1937 based on a tibiotarsus leg bone unearthed from a kitchen midden at a pre-Columbian site on St. Croix. A second specimen consisting of various bones from a similar site on Puerto Rico was described in 2008, while a coracoid from Montserrat may belong to this or another extinct species of macaw. The St. Croix macaw is one of 13 extinct macaw species that have been proposed to have lived on the Caribbean islands. Macaws were frequently transported long distances by humans in prehistoric and historical times, so it is impossible to know whether species known only from bones or accounts were native or imported. (Full article...)

Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all of Earth's water is contained in its global ocean, covering 70.8% of Earth's crust. The remaining 29.2% of Earth's crust is land, most of which is located in the form of continental landmasses within Earth's land hemisphere. Most of Earth's land is somewhat humid and covered by vegetation, while large sheets of ice at Earth's polar deserts retain more water than Earth's groundwater, lakes, rivers and atmospheric water combined. Earth's crust consists of slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth has a liquid outer core that generates a magnetosphere capable of deflecting most of the destructive solar winds and cosmic radiation. (Full article...)

Artificial intelligence (AI), in its broadest sense, is intelligence exhibited by machines, particularly computer systems. It is a field of research in computer science that develops and studies methods and software that enable machines to perceive their environment and use learning and intelligence to take actions that maximize their chances of achieving defined goals. Such machines may be called AIs. (Full article...)

Science is a strict systematic discipline that builds and organizes knowledge in the form of testable hypotheses and predictions about the world. Modern science is typically divided into three major branches: the natural sciences (e.g., physics, chemistry, and biology), which study the physical world; the social sciences (e.g., economics, psychology, and sociology), which study individuals and societies; and the formal sciences (e.g., logic, mathematics, and theoretical computer science), which study formal systems, governed by axioms and rules. There is disagreement whether the formal sciences are scientific disciplines, as they do not rely on empirical evidence. Applied sciences are disciplines that use scientific knowledge for practical purposes, such as in engineering and medicine. (Full article...)

Ejaculation is the discharge of semen (the ejaculate; normally containing sperm) through the urethra in men. It is normally linked with orgasm, which involves involuntary contractions of the pelvic floor. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. Ejaculation can occur spontaneously during sleep, and is a normal part of human sexual development (a nocturnal emission or "wet dream"). In rare cases, ejaculation occurs because of prostatic disease. Anejaculation is the condition of being unable to ejaculate. Ejaculation is normally intensely pleasurable for men; dysejaculation is an ejaculation that is painful or uncomfortable. Retrograde ejaculation is the backward flow of semen into the bladder rather than out of the urethra. (Full article...)

In statistics, the standard deviation is a measure of the amount of variation of a random variable expected about its mean. A low standard deviation indicates that the values tend to be close to the mean (also called the expected value) of the set, while a high standard deviation indicates that the values are spread out over a wider range. The standard deviation is commonly used in the determination of what constitutes an outlier and what does not. (Full article...)

An error (from the Latin errāre, meaning 'to wander') is an inaccurate or incorrect action, thought, or judgement. (Full article...)

A planet is a large, rounded astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets by the most restrictive definition of the term: the terrestrial planets Mercury, Venus, Earth, and Mars, and the giant planets Jupiter, Saturn, Uranus, and Neptune. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. Planets grow in this disk by the gradual accumulation of material driven by gravity, a process called accretion. (Full article...)

Sci-Hub is a shadow library website that provides free access to millions of research papers, regardless of copyright, by bypassing publishers' paywalls in various ways. Unlike Library Genesis, it does not provide access to books. Sci-Hub was founded in Kazakhstan by Alexandra Elbakyan in 2011, in response to the high cost of research papers behind paywalls (see Serials crisis). The site is extensively used worldwide. In September 2019, the site's operator(s) said that it served approximately 400,000 requests per day.
In addition to its intensive use, Sci-Hub stands out among other shadow libraries because of its easy use/reliability and because of the enormous size of its collection; a 2018 study estimated that Sci-Hub provided access to 95% of all scholarly publications with issued DOI numbers, and on 15 July 2022, Sci-Hub reported that its collection comprised 88,343,822 files. However, due to legal troubles (see legal section) the site has paused uploads. (Full article...)

Anthropomorphism is the attribution of human traits, emotions, or intentions to non-human entities. It is considered to be an innate tendency of human psychology. Personification is the related attribution of human form and characteristics to abstract concepts such as nations, emotions, and natural forces, such as seasons and weather. Both have ancient roots as storytelling and artistic devices, and most cultures have traditional fables with anthropomorphized animals as characters. People have also routinely attributed human emotions and behavioral traits to wild as well as domesticated animals. (Full article...)

Physics is the natural science of matter, involving the study of matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines. A scientist who specializes in the field of physics is called a physicist. (Full article...)