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For a topic outline of science, see Outline of science.

Scientific method

An undergraduate student handles chemicals

Science (from the Latin word scientia, meaning "knowledge") is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.

The earliest roots of science can be traced to Ancient Egypt and Mesopotamia in around 3000 to 1200 BCE. Their contributions to mathematics, astronomy, and medicine entered and shaped Greek natural philosophy of classical antiquity, whereby formal attempts were made to provide explanations of events in the physical world based on natural causes. After the fall of the Western Roman Empire, knowledge of Greek conceptions of the world deteriorated in Western Europe during the early centuries (400 to 1000 CE) of the Middle Ages, but was preserved in the Muslim world during the Islamic Golden Age. The recovery and assimilation of Greek works and Islamic inquiries into Western Europe from the 10th to 13th century revived "natural philosophy", which was later transformed by the Scientific Revolution that began in the 16th century as new ideas and discoveries departed from previous Greek conceptions and traditions. The scientific method soon played a greater role in knowledge creation and it was not until the 19th century that many of the institutional and professional features of science began to take shape; along with the changing of "natural philosophy" to "natural science."

Modern science is typically divided into three major branches that consist of the natural sciences (e.g., biology, chemistry, and physics), which study nature in the broadest sense; 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 deal with symbols governed by rules. There is disagreement, however, on whether the formal sciences actually constitute a science as they do not rely on empirical evidence. Disciplines that use existing scientific knowledge for practical purposes, such as engineering and medicine, are described as applied sciences.

New knowledge in science is advanced by research from scientists who are motivated by curiosity about the world and a desire to solve problems. Contemporary scientific research is highly collaborative and is usually done by teams in academic and research institutions, government agencies, and companies. The practical impact of their work has led to the emergence of science policies that seek to influence the scientific enterprise by prioritizing the development of commercial products, armaments, health care, public infrastructure, and environmental protection. (Full article...)

Selected article

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  The effects of Hurricane Isabel in Delaware resulted in one of only thirteen presidential disaster declarations for the state of Delaware. Hurricane Isabel formed from a tropical wave on September 6, 2003 in the tropical Atlantic Ocean. It moved northwestward, and within an environment of light wind shear and warm waters it steadily strengthened to reach peak winds of 165 mph (265 km/h) on September 11. After fluctuating in intensity for four days, Isabel gradually weakened and made landfall on the Outer Banks of North Carolina with winds of 105 mph (165 km/h) on September 18. It quickly weakened over land and became extratropical over Pennsylvania the next day. The storm's center remained to the south and west of Delaware, and was about 175 miles (280 km) from the state at its closest approach. At that time, Isabel was a strong tropical storm located in central Virginia.
  
  The effects of the hurricane were compounded by flooding caused by the remnants of Tropical Storm Henri days before. Moderate winds of up to 62 mph (100 km/h) downed numerous trees, tree limbs, and power lines across the state, leaving at least 15,300 without power. Numerous low-lying areas were flooded due to high surf, strong storm surge, or run-off from flooding further inland. The passage of Hurricane Isabel resulted in $40 million in damage (2003 USD, ($56.3 million 2021 USD)) and no casualties in the state. Hurricane Isabel was the ninth named storm of the 2003 Atlantic hurricane season on September 6, 2003. (Full article...)
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  Known localities of V. gymnocaudus (red) and V. antsahabensis (green)

  
  Voalavo is a genus of rodent in the subfamily Nesomyinae, found only in Madagascar. Two species are known, both of which occur in mountain forest above 1250 m (4100 ft) altitude; the northern voalavo lives in northern Madagascar and eastern voalavo is restricted to a small area in the central part of the island. The genus was discovered in 1994 and formally described in 1998. Within Nesomyinae, it is most closely related to the genus Eliurus, and DNA sequence data suggest that the current definitions of these two genera need to be changed.
  
  Species of Voalavo are small, gray, mouse-like rodents, among the smallest nesomyines. They lack the distinctive tuft of long hairs on the tail that is characteristic of Eliurus. The tail is long and females have six mammae. In Voalavo, there are two glands on the chest (absent in Eliurus) that produce a sweet-smelling musk in breeding males. In the skull, the facial skeleton is long and the braincase is smooth. The incisive foramina (openings in the front part of the palate) are long and the bony palate itself is smooth. The molars are somewhat hypsodont (high-crowned), though less so than in Eliurus, and the third molars are reduced in size and complexity. (Full article...)
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  Chorioactis geaster

  
  Chorioactis is a genus of fungi that contains the single species Chorioactis geaster. The mushroom is commonly known as the devil's cigar or the Texas star in the United States, while in Japan it is called kirinomitake (キリノミタケ).
  This extremely rare mushroom is notable for its unusual appearance and disjunct distribution; it is found only in select locales in Texas and Japan. The fruit body, which grows on the stumps or dead roots of cedar elms (in Texas) or dead oaks (in Japan), somewhat resembles a dark brown or black cigar before it splits open radially into a starlike arrangement of four to seven leathery rays. The interior surface of the fruit body bears the spore-bearing tissue known as the hymenium, and is colored white to brown, depending on its age. The fruit body opening can be accompanied by a distinct hissing sound and the release of a smoky cloud of spores.
  
  Fruit bodies were first collected in Austin, Texas, and the species was named Urnula geaster in 1893; later it was found in Kyushu in 1937, but the mushroom was not reported again in Japan until 1973. Although the new genus Chorioactis was proposed to accommodate the unique species a few years after its original discovery, it was not accepted as a valid genus until 1968. Its classification has also been a source of confusion. Historically, Chorioactis was placed in the fungus family Sarcosomataceae, despite inconsistencies in the microscopic structure of the ascus, the saclike structure in which spores are formed. Phylogenetic analyses of the past decade have clarified the fungus's classification: Chorioactis, along with three other genera, make up the family Chorioactidaceae, a grouping of related fungi formally acknowledged in 2008. In 2009, Japanese researchers reported discovering a form of the fungus missing the sexual stage of its lifecycle; this asexual state was named Kumanasamuha geaster. (Full article...)
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  Male at at Head Marala, Punjab, Pakistan
  

  
  The Sind sparrow (Passer pyrrhonotus) is a passerine bird of the sparrow family, Passeridae, found around the Indus valley region in South Asia. It is also known as the jungle, Sind jungle, or rufous-backed sparrow. Very similar to the related house sparrow, it is smaller and has distinguishing plumage features. As in the house sparrow, the male has brighter plumage than female and young birds, including black markings and a grey crown. Distinctively, the male has a chestnut stripe running down its head behind the eye, and the female has a darker head than other sparrow species. Its main vocalisations are soft chirping calls that are extended into longer songs with other sounds interspersed by breeding males. Historically, this species was thought to be very closely related to the house sparrow, but its closest evolutionary affinities may lie elsewhere. The species was discovered around 1840, but went undetected for several decades afterwards.
  
  Within its Indus valley breeding range in Pakistan and western India, the Sind sparrow is patchily distributed in riverine and wetland habitats with thorny scrub and tall grass. During the non-breeding season, some birds enter drier habitats as they disperse short distances from their breeding habitat, or migrate into western Pakistan and the extreme east of Iran. Since this species is fairly common and expanding its range, it is assessed as least concern on the IUCN Red List. The Sind sparrow is social while feeding and gathers in small groups both while breeding and during winter dispersal. It feeds mostly on seeds and less often on insects, foraging close to the ground. Nests are made in the branches of thorny trees, and are untidy globular masses constructed from grass or other plant matter and lined with softer material. Both sexes are involved in building the nest and caring for the young, and usually raise two clutches of three to five young each breeding season. (Full article...)
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  The black-necked grebe or eared grebe (Podiceps nigricollis) is a member of the grebe family of water birds. It was described in 1831 by Christian Ludwig Brehm. There are currently three accepted subspecies, including the nominate subspecies. Its breeding plumage features a distinctive ochre-coloured plumage which extends behind its eye and over its ear coverts. The rest of the upper parts, including the head, neck, and breast, are coloured black to blackish brown. The flanks are tawny rufous to maroon-chestnut, and the abdomen is white. When in its non-breeding plumage, this bird has greyish-black upper parts, including the top of the head and a vertical stripe on the back of the neck. The flanks are also greyish-black. The rest of the body is a white or whitish colour. The juvenile has more brown in its darker areas. The subspecies californicus can be distinguished from the nominate by the former's usually longer bill. The other subspecies, P. n. gurneyi, can be differentiated by its greyer head and upper parts and by its smaller size. P. n. gurneyi can also be told apart by its lack of a non-breeding plumage. This species is present in parts of Africa, Eurasia, and the Americas.
  
  The black-necked grebe uses multiple foraging techniques. Insects, which make up the majority of this bird's diet, are caught either on the surface of the water or when they are in flight. It occasionally practices foliage gleaning. This grebe dives to catch crustaceans, molluscs, tadpoles, and small frogs and fish. When moulting at saline lakes, this bird feeds mostly on brine shrimp. The black-necked grebe makes a floating cup nest on an open lake. The nest cup is covered with a disc. This nest is located both in colonies and by itself. During the breeding season, which varies depending on location, this species will lay one (sometimes two) clutch of three to four eggs. The number of eggs is sometimes larger due to conspecific brood parasitism. After a 21-day incubation period, the eggs hatch, and then the nest is deserted. After about 10 days, the parents split up the chicks between themselves. After this, the chicks become independent in about 10 days, and fledge in about three weeks. (Full article...)
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  Hurricane Marie is tied as the seventh-most intense Pacific hurricane on record, attaining a barometric pressure of 918 mbar (hPa; 27.11 inHg) in August 2014 and the sixth-most intense tropical cyclone worldwide in 2014. The fourteenth named storm, ninth hurricane, and sixth major hurricane of the season, Marie began as a tropical wave that emerged off the west coast of Africa over the Atlantic Ocean on August 10. Some organization of shower and thunderstorm activity initially took place, but dry air soon impinged upon the system and imparted weakening. The wave tracked westward across the Atlantic and Caribbean for several days. On August 19, an area of low pressure consolidated within the wave west of Central America. With favorable atmospheric conditions, convective activity and banding features increased around the system and by August 22, the system acquired enough organization to be classified as Tropical Depression Thirteen-E while situated about 370 mi (595 km) south-southeast of Acapulco, Mexico. Development was initially fast-paced, as the depression acquired tropical storm-force winds within six hours of formation and hurricane-force by August 23. However, due to some vertical wind shear its intensification rate stalled, and for a time it remained a Category 1 hurricane on the Saffir–Simpson hurricane wind scale.
  
  On August 24, Marie developed an eye and rapidly intensified to a Category 5 hurricane with winds of 160 km/h (100 mph). At its peak, the hurricane's gale-force winds spanned an area 575 mi (925 km) across. Marie subsequently underwent an eyewall replacement cycle on August 25 which prompted steady weakening. Over the next several days, Marie progressively degraded to below hurricane strength as it moved into an increasingly hostile environment with cooler waters and a more stable atmosphere. On August 29, after having lost all signs of organized deep convection, Marie degenerated into a remnant low. The large system gradually wound down over the following several days, with winds subsiding below gale-force on August 30. The remnant cyclone eventually lost a well defined center and dissipated on September 2 about 1,200 mi (1,950 km) northeast of Hawaii. (Full article...)
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  Tropical Storm Kiko was a strong tropical storm that capsized a boat off the western coast of Mexico, killing at least 15 people. The 15th and final tropical cyclone of the 2007 Pacific hurricane season, Kiko developed out of a tropical wave that formed off the coast of Africa on September 26 and traversed the Atlantic. The wave crossed over Central America and entered the Pacific Ocean on October 8, where it spawned Tropical Depression 15-E on October 15. The depression drifted to the south over the next day before briefly being declared Tropical Storm Kiko. It subsequently weakened into a tropical depression, but later reattained tropical storm intensity. By October 18, Kiko was forecast to make landfall along the western Mexican coastline as a moderate tropical storm. However, the cyclone turned to the west and reached its peak intensity of 70 mph (110 km/h) on October 20. The tropical storm slowly weakened to a remnant low-pressure area by October 24 and completely dissipated on October 27 without making landfall. (Full article...)
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  Ben Gascoigne at the Stromlo Observatory, 1948

  
  Sidney Charles Bartholemew "Ben" Gascoigne AO (11 November 1915 – 25 March 2010) was a New Zealand-born Australian optical astronomer and expert in photometry who played a leading role in the design and commissioning of Australia's largest optical telescope, the Anglo-Australian Telescope, which for a time was one of the world's most important astronomical facilities. Born in Napier, New Zealand, Gascoigne trained in Auckland and at the University of Bristol, before moving to Australia during World War II to work at the Commonwealth Solar Observatory at Mount Stromlo in Canberra. He became skillful in the design and manufacture of optical devices such as telescope elements.
  
  Following the war, Gascoigne and astronomer Gerald Kron used newly modernised telescopes at Mount Stromlo to determine that the distance between our galaxy and the Magellanic Cloud dwarf galaxies had been underestimated by a factor of two. Because this measurement was used to calibrate other distances in astronomy, the result effectively doubled the estimated size of the universe. They also found that star formation in the Magellanic Clouds had occurred more recently than in the Milky Way; this overturned the prevailing view that both had evolved in parallel. A major figure at Mount Stromlo Observatory, Gascoigne helped it develop from a solar observatory to a centre of stellar and galactic research, and was instrumental in the creation of its field observatory in northern New South Wales, Siding Spring Observatory. When the British and Australian governments agreed to jointly build the Anglo-Australian Telescope at Siding Spring, Gascoigne was involved from its initial conception and throughout its lengthy commissioning, taking its first photograph. Gascoigne was made an Officer of the Order of Australia for his contributions to astronomy and to the Anglo-Australian Telescope. (Full article...)
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  The great auk (Pinguinus impennis) is a species of flightless alcid that became extinct in the mid-19th century. It was the only modern species in the genus Pinguinus. It is not closely related to the birds now known as penguins, which were discovered later and so named by sailors because of their physical resemblance to the great auk.
  
  It bred on rocky, isolated islands with easy access to the ocean and a plentiful food supply, a rarity in nature that provided only a few breeding sites for the great auks. When not breeding, they spent their time foraging in the waters of the North Atlantic, ranging as far south as northern Spain and along the coastlines of Canada, Greenland, Iceland, the Faroe Islands, Norway, Ireland, and Great Britain. (Full article...)
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  Inocybe saliceticola is a fungus found in moist habitats in the Nordic countries. The species produces brown mushrooms with caps of varying shapes up to 40 millimetres (1.6 in) across, and tall, thin stems up to 62 millimetres (2.4 in) long. At the base of the stem is a large and well-defined "bulb". The species produces unusually shaped, irregular spores, each with a few thick protrusions. This feature helps differentiate it from other species that would otherwise be similar in appearance and habit.
  
  Inocybe saliceticola grows in mycorrhizal association with willow trees, and it is for this that the species is named. However, particular species favoured by the fungus are unclear and may include beech and alder taxa. The mushrooms grow from the ground, often among mosses or detritus. I. saliceticola was first described in 2009, and within the genus Inocybe, the species is a part of the section Marginatae. The species has been recorded in Finland and Sweden and is relatively common in some areas. (Full article...)
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  Banksia verticillata, commonly known as granite banksia or Albany banksia, is a species of shrub or (rarely) tree of the genus Banksia in the family Proteaceae. It is native to the southwest of Western Australia and can reach up to 3 m (10 ft) in height. It can grow taller to 5 m (16 ft) in sheltered areas, and much smaller in more exposed areas. This species has elliptic green leaves and large, bright golden yellow inflorescences or flower spikes, appearing in summer and autumn. The New Holland honeyeater (Phylidonyris novaehollandiae) is the most prominent pollinator, although several other species of honeyeater, as well as bees, visit the flower spikes.
  
  A declared vulnerable species, it occurs in two disjunct populations on granite outcrops along the south coast of Western Australia, with the main population near Albany and a smaller population near Walpole, and is threatened by dieback (Phytophthora cinnamomi) and aerial canker (Zythiostroma). B. verticillata is killed by bushfire and new plants regenerate from seed afterwards. Populations take over a decade to produce seed and fire intervals of greater than twenty years are needed to allow the canopy seed bank to accumulate. (Full article...)
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  Debora J. Green (née Jones) is an American physician who pleaded no contest to setting a 1995 fire which burned down her family's home and killed two of her children, and to poisoning her husband with ricin with the intention of causing his death. The case was sensational, and covered heavily by news media, especially in the Kansas–Missouri area, where the crimes occurred. Though Green has petitioned for a new trial twice in recent years, her requests have not been successful.
  
  Green married Michael Farrar in 1979 while practicing as an emergency physician. The marriage was tumultuous, and Farrar filed for divorce in July 1995. Between August and September 1995, Farrar repeatedly fell violently ill, and despite numerous hospitalizations his doctors could not pinpoint the source of his illness. Green's emotional stability deteriorated and she began to drink heavily, even while supervising her children. On October 24, 1995, the Farrar family home, occupied by Green and the couple's three children, caught fire. Kate Farrar and Debora Green escaped without harm, but despite the efforts of firefighters, Timothy and Kelly Farrar died in the blaze. Investigation showed that trails of accelerant in the house led back to Green's bedroom, and that the source of Michael Farrar's intractable illness had been ricin, a poison served to him in his food by Green. (Full article...)
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  A Haflinger mare and foal

  
  The Haflinger, also known as the Avelignese, is a breed of horse developed in Austria and northern Italy (namely Hafling in South Tyrol region) during the late 19th century. Haflinger horses are relatively small, are always chestnut with flaxen mane and tail, have distinctive gaits described as energetic but smooth, and are well-muscled yet elegant. The breed traces its ancestry to the Middle Ages; several theories for its origin exist. Haflingers, developed for use in mountainous terrain, are known for their hardiness. Their current conformation and appearance are the result of infusions of bloodlines from Arabian and various European breeds into the original native Tyrolean ponies. The foundation sire, 249 Folie, was born in 1874; by 1904, the first breeders' cooperative was formed. All Haflingers can trace their lineage back to Folie through one of seven bloodlines. World Wars I and II, as well as the Great Depression, had a detrimental effect on the breed, and lower-quality animals were used at times to save the breed from extinction. During World War II, breeders focused on horses that were shorter and more draft-like, favored by the military for use as packhorses. The emphasis after the war shifted toward animals of increased refinement and height.
  
  In the postwar era, the Haflinger was indiscriminately crossed with other breeds and some observers feared the breed was in renewed danger of extinction. However, starting in 1946, breeders focused on producing purebred Haflingers and a closed stud book was created. Interest in the breed increased in other countries, and between 1950 and 1974, the population grew, even while the overall European horse population decreased. Population numbers continued to increase steadily, and as of 2005, almost 250,000 Haflingers existed worldwide. Breeding farms are in several countries, although most of the breeding stock still comes from Austria. In 2003, a Haflinger became the first horse to be cloned, resulting in a filly named Prometea. (Full article...)
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  Splitting of the slate blocks with hammer and chisel to produce roofing slates requires great skill. This process was not mechanized until the second half of the 20th century, and some slate is still produced in this way. These quarrymen are working at the Dinorwic Quarry, Wales, about 1910.

  
  
  The existence of a slate industry in Wales is attested since the Roman period, when slate was used to roof the fort at Segontium, now Caernarfon. The slate industry grew slowly until the early 18th century, then expanded rapidly until the late 19th century, at which time the most important slate producing areas were in northwest Wales, including the Penrhyn Quarry near Bethesda, the Dinorwic Quarry near Llanberis, the Nantlle Valley quarries, and Blaenau Ffestiniog, where the slate was mined rather than quarried. Penrhyn and Dinorwig were the two largest slate quarries in the world, and the Oakeley mine at Blaenau Ffestiniog was the largest slate mine in the world. Slate is mainly used for roofing, but is also produced as thicker slab for a variety of uses including flooring, worktops and headstones.
  
  Up to the end of the 18th century, slate was extracted on a small scale by groups of quarrymen who paid a royalty to the landlord, carted slate to the ports, and then shipped it to England, Ireland and sometimes France. Towards the close of the century, the landowners began to operate the quarries themselves, on a larger scale. After the government abolished slate duty in 1831, rapid expansion was propelled by the building of narrow gauge railways to transport the slates to the ports. (Full article...)
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  Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American paleontologist, comparative anatomist, herpetologist, and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of 19. Though his father tried to raise Cope as a gentleman farmer, he eventually acquiesced to his son's scientific aspirations. Cope married his cousin and had one child; the family moved from Philadelphia to Haddonfield, New Jersey, although Cope would maintain a residence and museum in Philadelphia in his later years.
  
  Cope had little formal scientific training, and he eschewed a teaching position for field work. He made regular trips to the American West, prospecting in the 1870s and 1880s, often as a member of United States Geological Survey teams. A personal feud between Cope and paleontologist Othniel Charles Marsh led to a period of intense fossil-finding competition now known as the Bone Wars. Cope's financial fortunes soured after failed mining ventures in the 1880s, forcing him to sell off much of his fossil collection. He experienced a resurgence in his career toward the end of his life before dying on April 12, 1897. (Full article...)

Selected image

Deep Impact (space mission)

Credit: NASA

Deep Impact is a NASA space probe designed to study the composition of the interior of the comet Tempel 1. At 5:52 UTC on July 4, 2005, one section of the Deep Impact probe successfully impacted the comet's nucleus, excavating debris from the interior of the nucleus. Photographs of the impact showed the comet to be more dusty and less icy than expected. The impact generated a large, bright dust cloud that obscured the hoped-for view of the impact crater.

Selected biography

Wolfgang Ernst Pauli (April 25, 1900 – December 15, 1958) was an Austrian physicist noted for his work on the theory of spin, and in particular the discovery of the Exclusion principle, which underpins the whole of chemistry and quantum mechanics.

He seldom published papers, preferring lengthy correspondences with colleagues (such as Bohr and Heisenberg, with whom he had close friendships.) Many of his ideas and results were never published and appeared only in his letters, which were often copied and circulated by their recipients. Pauli was apparently unconcerned that much of his work thus went uncredited.

Did you know...

• ...that the gestation period of the ring-tailed lemur (pictured) is approximately 146 days?
• ...that the Late November 2006 Nor'easter caused winds up to 80 mph (70 knots) in the Outer Banks of North Carolina, the earliest snowfall on record for Savannah, Georgia and Charleston, South Carolina, as well as Charleston, South Carolina's only occurrence of thundersnow on record?
• ...that the Rufous-crowned Sparrow, a medium-sized sparrow of the southwestern United States and Mexico, has a subspecies endemic to the Todos Santos Islands that has not been seen since the 1970s?
• ...that the Christmas 1994 Nor'easter led to wind gusts of 99 mph/86 knots in Massachusetts, and briefly formed an eye?
• ...that the Northern Red-legged Frog is a near-threatened species, whose male defends breeding pond territory with nocturnal displays?

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