Emilia Fox

Emilia Fox

Emilia Rose Elizabeth Fox[2][3] (born 31 July 1974) is an English actress and presenter whose film debut was in Roman Polanski's film The Pianist. Her other notable films include the Italian–French–British romance-drama film The Soul Keeper (2002), for which she won the Flaiano Film Award for Best Actress; the drama film The Republic of Love (2003); the comedy-drama film Things to Do Before You're 30 (2005); the black comedy Keeping Mum (2005); the romantic comedy-drama film Cashback (2006); the drama Flashbacks of a Fool (2008); the drama film Ways to live Forever (2010); the drama-thriller A Thousand Kisses Deep (2011); and the fantasy-horror drama film Dorian Gray (2009).

Fox's television roles include the BBC drama Pride and Prejudice (1995), the PBS British/German television serial Rebecca (1997), ITV Granada's Henry VIII (2003), BBC's Gunpowder, Treason & Plot (2004), the 2005 BBC miniseries The Virgin Queen (2005) and the ITV crime drama series Fallen Angel (2007). She also appeared as Morgause in the BBC's Merlin, beginning in the programme's second series. Fox also starred in Delicious (2016). She stars as Dr. Nikki Alexander on BBC crime drama Silent Witness, having joined the cast in 2004 following the departure of Amanda Burton. Fox is the longest serving cast member since the departures of Tom Ward in 2012 and William Gaminara in 2013. Fox has currently played the role of Nikki for 16 years.

In Britain, Fox has performed in plays with high-profile actors such as Les Liaisons Dangereuses with Jared Harris and Coriolanus with Ralph Fiennes.

Personal life

Fox was born in Hammersmith, London.[1] She comes from a thespian family — her mother is actress Joanna David (née Joanna Elizabeth Hacking) and her father is actor Edward Fox. Her uncle is James Fox and her cousins Jack, Laurence and Lydia also have successful acting careers.[4] She has a brother, Freddie (also an actor), and a half sister, Lucy.[2] She was educated at the independent Bryanston School in Dorset, where she played the cello, and at St Catherine's College, Oxford, where she read English.[5][6] Her great-great grandfather was Samson Fox, a self-made millionaire, and her great-grandmother was the actress Hilda Hanbury, sister of Lily Hanbury. Her grandfather was Robin Fox, a theatrical agent.[7] Through Hanbury, she is related to the Terry family of actors.[8]

In 2000 Fox was engaged to the comedian Vic Reeves and subsequently dated Toby Mott.[9][10] In July 2005, she married the British actor Jared Harris, the son of the Irish actor Richard Harris. The couple announced their split in 2008, and Harris filed for divorce in January 2009.[11] The divorce followed the breakdown of their long-distance relationship and her having a miscarriage in 2007.[12]

Fox later entered into a relationship with actor Jeremy Gilley, and in May 2010 it was reported that Fox was pregnant with their child.[13] The Harris-Fox divorce was finalised in June 2010.[citation needed] In November 2010, Fox gave birth to a baby girl named Rose.[14]

Fox is a patron of the environmental and human rights charity the Environmental Justice Foundation.[15] She speaks German and French. She plays the cello, the piano and the trumpet.[16][failed verification]

Career

Fox first appeared as Georgiana, the sister of Colin Firth's Mr. Darcy, in the 1995 television adaptation of Pride and Prejudice, followed by her role as the second Mrs. de Winter in the 1997 television adaptation of Rebecca, opposite Charles Dance. In 1998 she starred with Ben Miles in the adaptation of Catherine Cookson's The Round Tower as the young Vanessa Radcliffe, a wealthy girl from an affluent family who is forced to leave her home after becoming pregnant. Fox played Jeannie Hurst in the 2000 remake of Randall and Hopkirk.

In 2002 she starred in The Pianist as Dorota, a beautiful, blond, non-Jewish cellist who adores the playing of the Polish-Jewish pianist and composer Władysław Szpilman (played by Adrien Brody). The film was directed by Roman Polanski. In 2003, she played Jane Seymour in a two-part television biographical film about King Henry VIII. She also played the title role in Katherine Howard, directed by Robin Lefevre at the Chichester Festival Theatre in 1998.

In 2004, she joined the cast of the crime drama, Silent Witness. As of 2020, she is still in the show and has now played the role of Nikki Alexander for sixteen years. Also in 2004, she played Lady Margaret in Part 2 of Gunpowder, Treason and Plot, the mini-series about James I (James VI in Scotland) and the Gunpowder Plot. In 2005, Fox appeared in the BBC miniseries The Virgin Queen, a four-part miniseries based upon the life of Queen Elizabeth I,Fox played Amy Dudley, the first wife of Robert Dudley, played by Tom Hardy, despite appearing in only one episode, her character remains a key character in the series. In 2008 she played Sister Jean in Baillie Walsh's Flashbacks of a Fool, which also featured Daniel Craig. She also starred in Things To Do Before You're 30 with Billie Piper, who would later marry her first cousin Laurence Fox, although in 2016 they divorced.

She was cast as Lynne Frederick in the 2004 film The Life and Death of Peter Sellers, which starred Geoffrey Rush in the lead role. A whole section of the film focusing on the Frederick/Sellers relationship was removed in the final edit, although she can be seen briefly in a background shot towards the end of the film. The deleted scenes with Fox can be found among the special features on the DVD release of the film.

in 2007, Fox reunited with her Rebecca co-star Charles Dance when they starred together in the ITV1 mini-series Fallen Angel, Fox played a serial killer Rosie Byfield, with Dance appearing as her father. The rewind format in which the show was shot traced the development of the killer streak of Fox's character. Fox and Dance had previously both appeared in ITV1's Henry VIII, but Dance's role as the Duke of Buckingham was limited, as his character was arrested for treason less than fifteen minutes into the first half, while Fox's scenes as the doomed third Queen Jane Seymour dominated the first half of the second episode. In the 2008 English language DVD re-release of the cult 2006 Norwegian animated film Free Jimmy, Fox voiced the character of "Bettina". The dialogue was written by Simon Pegg; other actors included Pegg himself and Woody Harrelson. Emilia Fox narrates the popular children's book We're Going on a Bear Hunt (by Michael Rosen and Helen Oxenbury) with Kevin Whately in a special edition book and DVD set. She appeared as Morgause in the second series of BBC's Merlin in 2009. She returned for the third and fourth series. Also in 2009, she portrayed Queen Elizabeth II in the Channel 4 documentary The Queen.

She narrated the Doctor Who character Lady Winters in the Doctor Who Adventure Game, The Gunpowder Plot, (2011).[17] She had previously played Bernice in the Eighth Doctor audio drama Nevermore.[18]

In 2015 she appeared as Julia Swetlove in the BBC's dramatisation of J. K. Rowling's book The Casual Vacancy. In 2016 she appeared in series 2 of The Tunnel as Vanessa Hamilton. In 2016–18 she has starred as Sam Vincent in Delicious, a Sky television drama. Silent Witness, in which Fox stars, resumed on BBC1 in January 2018.

Cat

Cat

The cat (Felis catus) is a domestic species of small carnivorous mammal.[1][2] It is the only domesticated species in the family Felidae and is often referred to as the domestic cat to distinguish it from the wild members of the family.[4] A cat can either be a house cat, a farm cat or a feral cat; the latter ranges freely and avoids human contact.[5] Domestic cats are valued by humans for companionship and their ability to hunt pests such as rodents. About 60 cat breeds are recognized by various cat registries.[6]

The cat is similar in anatomy to the other felid species: it has a strong flexible body, quick reflexes, sharp teeth and retractable claws adapted to killing small prey. Its night vision and sense of smell are well developed. Cat communication includes vocalizations like meowing, purring, trilling, hissing, growling and grunting as well as cat-specific body language. It is a solitary hunter but a social species. It can hear sounds too faint or too high in frequency for human ears, such as those made by mice and other small mammals. It is a predator that is most active at dawn and dusk.[7] It secretes and perceives pheromones.[8]

Female domestic cats can have kittens from spring to late autumn, with litter sizes ranging from two to five kittens.[9] Domestic cats are bred and shown at events as registered pedigreed cats, a hobby known as cat fancy. Failure to control breeding of pet cats by spaying and neutering, as well as abandonment of pets, resulted in large numbers of feral cats worldwide, contributing to the extinction of entire bird species and evoking population control.[10]

It was long thought that cat domestication was initiated in Ancient Egypt, because cats in ancient Egypt were venerated since around 3100 BC.[11][12] However, the earliest indication for the taming of an African wildcat (F. lybica) was found in Cyprus, where a cat skeleton was excavated close by a human Neolithic grave dating to around 7500 BC.[13] African wildcats were probably first domesticated in the Near East.[14]

As of 2017, the domestic cat was the second-most popular pet in the United States by number of pets owned, after freshwater fish,[15] with 95 million cats owned.[16][17] In the United Kingdom, around 7.3 million cats lived in more than 4.8 million households as of 2019.[18]

Etymology and naming

The origin of the English word 'cat', Old English catt, is thought to be the Late Latin word cattus, which was first used at the beginning of the 6th century.[19] It was suggested that the word 'cattus' is derived from an Egyptian precursor of Coptic ϣⲁⲩ šau, "tomcat", or its feminine form suffixed with -t.[20] The Late Latin word is also thought to be derived from Afro-Asiatic languages.[21] The Nubian word kaddîska "wildcat" and Nobiin kadīs are possible sources or cognates.[22] The Nubian word may be a loan from Arabic قَطّ‎ qaṭṭ ~ قِطّ qiṭṭ. It is "equally likely that the forms might derive from an ancient Germanic word, imported into Latin and thence to Greek and to Syriac and Arabic".[23] The word may be derived from Germanic and Northern European languages, and ultimately be borrowed from Uralic, cf. Northern Sami gáđfi, "female stoat", and Hungarian hölgy, "stoat"; from Proto-Uralic *käďwä, "female (of a furred animal)".[24]

The English puss, extended as pussy and pussycat, is attested from the 16th century and may have been introduced from Dutch poes or from Low German puuskatte, related to Swedish kattepus, or Norwegian pus, pusekatt. Similar forms exist in Lithuanian puižė and Irish puisín or puiscín. The etymology of this word is unknown, but it may have simply arisen from a sound used to attract a cat.[25][26]

A male cat is called a tom or tomcat[27] (or a gib,[28] if neutered) An unspayed female is called a queen,[29] especially in a cat-breeding context. A juvenile cat is referred to as a kitten. In Early Modern English, the word kitten was interchangeable with the now-obsolete word catling.[30] A group of cats can be referred to as a clowder or a glaring.[31]

Taxonomy

The scientific name Felis catus was proposed by Carl Linnaeus in 1758 for a domestic cat.[1][2] Felis catus domesticus was proposed by Johann Christian Polycarp Erxleben in 1777.[3] Felis daemon proposed by Konstantin Alekseevich Satunin in 1904 was a black cat from the Transcaucasus, later identified as a domestic cat.[32][33]

In 2003, the International Commission on Zoological Nomenclature ruled that the domestic cat is a distinct species, namely Felis catus.[34][35] In 2007, it was considered a subspecies of the European wildcat, F. silvestris catus, following results of phylogenetic research.[36][37] In 2017, the IUCN Cat Classification Taskforce followed the recommendation of the ICZN in regarding the domestic cat as a distinct species, Felis catus.[38]

Evolution

The domestic cat is a member of the Felidae, a family that had a common ancestor about 10–15 million years ago.[39] The genus Felis diverged from the Felidae around 6–7 million years ago.[40] Results of phylogenetic research confirm that the wild Felis species evolved through sympatric or parapatric speciation, whereas the domestic cat evolved through artificial selection.[41] The domesticated cat and its closest wild ancestor are both diploid organisms that possess 38 chromosomes[42] and roughly 20,000 genes.[43] The leopard cat (Prionailurus bengalensis) was tamed independently in China around 5500 BC. This line of partially domesticated cats leaves no trace in the domestic cat populations of today.[44]

Domestication

The earliest known indication for a tamed African wildcat was excavated close by a human grave in Shillourokambos, southern Cyprus, dating to about 9,200 to 9,500 years before present. As there is no evidence of native mammalian fauna on Cyprus, the inhabitants of this Neolithic village most likely brought the cat and other wild mammals to the island from the Middle Eastern mainland.[13] Scientists therefore assume that African wildcats were attracted to early human settlements in the Fertile Crescent by rodents, in particular the house mouse (Mus musculus), and were tamed by Neolithic farmers. This commensal relationship between early farmers and tamed cats lasted thousands of years. As agricultural practices spread, so did tame and domesticated cats.[14][6] Wildcats of Egypt contributed to the maternal gene pool of the domestic cat at a later time.[45] The earliest known evidence for the occurrence of the domestic cat in Greece dates to around 1200 BC. Greek, Phoenician, Carthaginian and Etruscan traders introduced domestic cats to southern Europe.[46] During the Roman Empire they were introduced to Corsica and Sardinia before the beginning of the 1st millennium.[47] By the 5th century BC, they were familiar animals around settlements in Magna Graecia and Etruria.[48] By the end of the Roman Empire in the 5th century, the Egyptian domestic cat lineage had arrived in a Baltic Sea port in northern Germany.[45]

During domestication, cats have undergone only minor changes in anatomy and behavior, and they are still capable of surviving in the wild. Several natural behaviors and characteristics of wildcats may have preadapted them for domestication as pets. These traits include their small size, social nature, obvious body language, love of play and relatively high intelligence. Captive Leopardus cats may also display affectionate behavior toward humans, but were not domesticated.[49] House cats often mate with feral cats,[50] producing hybrids such as the Kellas cat in Scotland.[51] Hybridisation between domestic and other Felinae species is also possible.[52]

Development of cat breeds started in the mid 19th century.[53] An analysis of the domestic cat genome revealed that the ancestral wildcat genome was significantly altered in the process of domestication as specific mutations were selected to develop cat breeds.[54] Most breeds are founded on random-bred domestic cats. Genetic diversity of these breeds varies between regions, and is lowest in purebred populations, which show more than 20 deleterious genetic disorders.[55]

Characteristics

Size

The domestic cat has a smaller skull and shorter bones than the European wildcat.[56] It averages about 46 cm (18 in) in head-to-body length and 23–25 cm (9.1–9.8 in) in height, with about 30 cm (12 in) long tails. Males are larger than females.[57] Adult domestic cats typically weigh between 4 and 5 kg (8.8 and 11.0 lb).[41]

Skeleton

Cats have seven cervical vertebrae (as do most mammals); 13 thoracic vertebrae (humans have 12); seven lumbar vertebrae (humans have five); three sacral vertebrae (as do most mammals, but humans have five); and a variable number of caudal vertebrae in the tail (humans have only vestigial caudal vertebrae, fused into an internal coccyx).[58]:11 The extra lumbar and thoracic vertebrae account for the cat's spinal mobility and flexibility. Attached to the spine are 13 ribs, the shoulder, and the pelvis.[58] :16 Unlike human arms, cat forelimbs are attached to the shoulder by free-floating clavicle bones which allow them to pass their body through any space into which they can fit their head.[59]

Skull

The cat skull is unusual among mammals in having very large eye sockets and a powerful specialized jaw.[60]:35 Within the jaw, cats have teeth adapted for killing prey and tearing meat. When it overpowers its prey, a cat delivers a lethal neck bite with its two long canine teeth, inserting them between two of the prey's vertebrae and severing its spinal cord, causing irreversible paralysis and death.[61] Compared to other felines, domestic cats have narrowly spaced canine teeth relative to the size of their jaw, which is an adaptation to their preferred prey of small rodents, which have small vertebrae.[61] The premolar and first molar together compose the carnassial pair on each side of the mouth, which efficiently shears meat into small pieces, like a pair of scissors. These are vital in feeding, since cats' small molars cannot chew food effectively, and cats are largely incapable of mastication.[60]:37 Although cats tend to have better teeth than most humans, with decay generally less likely because of a thicker protective layer of enamel, a less damaging saliva, less retention of food particles between teeth, and a diet mostly devoid of sugar, they are nonetheless subject to occasional tooth loss and infection.[62]

Ambulation

The cat is digitigrade. It walks on the toes, with the bones of the feet making up the lower part of the visible leg.[63] Unlike most mammals, it uses a "pacing" gait and moves both legs on one side of the body before the legs on the other side. It registers directly by placing each hind paw close to the track of the corresponding fore paw, minimizing noise and visible tracks. This also provides sure footing for hind paws when navigating rough terrain. As it speeds up walking to trotting, its gait changes to a "diagonal" gait: the diagonally opposite hind and fore legs move simultaneously.[64]

Claws

Cats have protractable and retractable claws.[65] In their normal, relaxed position, the claws are sheathed with the skin and fur around the paw's toe pads. This keeps the claws sharp by preventing wear from contact with the ground and allows the silent stalking of prey. The claws on the fore feet are typically sharper than those on the hind feet.[66] Cats can voluntarily extend their claws on one or more paws. They may extend their claws in hunting or self-defense, climbing, kneading, or for extra traction on soft surfaces. Cats shed the outside layer of their claw sheaths when scratching rough surfaces.[67]

Most cats have five claws on their front paws, and four on their rear paws. The dewclaw is proximal to the other claws. More proximally is a protrusion which appears to be a sixth "finger". This special feature of the front paws, on the inside of the wrists has no function in normal walking, but is thought to be an antiskidding device used while jumping. Some cat breeds are prone to having extra digits (polydactyly).[68] Polydactylous cats occur along North America's northeast coast and in Great Britain.[69]

Senses

Cats have excellent night vision and can see at only one-sixth the light level required for human vision.[60]:43 This is partly the result of cat eyes having a tapetum lucidum, which reflects any light that passes through the retina back into the eye, thereby increasing the eye's sensitivity to dim light.[70] Large pupils are an adaptation to dim light. The domestic cat has slit pupils, which allow it to focus bright light without chromatic aberration.[71] At low light, a cat's pupils expand to cover most of the exposed surface of its eyes.[72] However, the domestic cat has rather poor color vision and only two types of cone cells, optimized for sensitivity to blue and yellowish green; its ability to distinguish between red and green is limited.[73] A response to middle wavelengths from a system other than the rod cells might be due to a third type of cone. However, this appears to be an adaptation to low light levels rather than representing true trichromatic vision.[74]

Hearing

The domestic cat's hearing is most acute in the range of 500 Hz to 32 kHz.[75] It can detect an extremely broad range of frequencies ranging from 55 Hz to 79,000 Hz. It can hear a range of 10.5 octaves, while humans and dogs can hear ranges of about 9 octaves.[76][77] Its hearing sensitivity is enhanced by its large movable outer ears, the pinnae, which amplify sounds and help detect the location of a noise. It can detect ultrasound, which enables it to detect ultrasonic calls made by rodent prey.[78][79]

Smell

Cats have an acute sense of smell, due in part to their well-developed olfactory bulb and a large surface of olfactory mucosa, about 5.8 cm2 (0.90 in2) in area, which is about twice that of humans.[80] Cats and many other animals have a Jacobson's organ in their mouths that is used in the behavioral process of flehmening. It allows them to sense certain aromas in a way that humans cannot. Cats are sensitive to pheromones such as 3-mercapto-3-methylbutan-1-ol,[81] which they use to communicate through urine spraying and marking with scent glands.[82] Many cats also respond strongly to plants that contain nepetalactone, especially catnip, as they can detect that substance at less than one part per billion.[83] About 70–80% of cats are affected by nepetalactone.[84] This response is also produced by other plants, such as silver vine (Actinidia polygama) and the herb valerian; it may be caused by the smell of these plants mimicking a pheromone and stimulating cats' social or sexual behaviors.[85]

Taste

Cats have relatively few taste buds compared to humans (470 or so versus more than 9,000 on the human tongue).[86] Domestic and wild cats share a taste receptor gene mutation that keeps their sweet taste buds from binding to sugary molecules, leaving them with no ability to taste sweetness.[87] Their taste buds instead respond to acids, amino acids like protein, and bitter tastes.[88] Cats also have a distinct temperature preference for their food, preferring food with a temperature around 38 °C (100 °F) which is similar to that of a fresh kill and routinely rejecting food presented cold or refrigerated (which would signal to the cat that the "prey" item is long dead and therefore possibly toxic or decomposing)

Lion

Lion

The lion (Panthera leo) is a species in the family Felidae; it is a muscular, deep-chested cat with a short, rounded head, a reduced neck and round ears, and a hairy tuft at the end of its tail. It is sexually dimorphic; adult male lions have a prominent mane, which is the most recognisable feature of the species. With a typical head-to-body length of 184–208 cm (72–82 in) they are larger than females at 160–184 cm (63–72 in). It is a social species, forming groups called prides. A lion pride consists of a few adult males, related females and cubs. Groups of female lions usually hunt together, preying mostly on large ungulates. The lion is an apex and keystone predator, although some lions scavenge when opportunities occur, and have been known to hunt humans, although the species typically does not.

Typically, the lion inhabits grasslands and savannas but is absent in dense forests. It is usually more diurnal than other big cats, but when persecuted it adapts to being active at night and at twilight. In the Pleistocene, the lion ranged throughout Eurasia, Africa and North America but today it has been reduced to fragmented populations in Sub-Saharan Africa and one critically endangered population in western India. It has been listed as Vulnerable on the IUCN Red List since 1996 because populations in African countries have declined by about 43% since the early 1990s. Lion populations are untenable outside designated protected areas. Although the cause of the decline is not fully understood, habitat loss and conflicts with humans are the greatest causes for concern.

One of the most widely recognised animal symbols in human culture, the lion has been extensively depicted in sculptures and paintings, on national flags, and in contemporary films and literature. Lions have been kept in menageries since the time of the Roman Empire and have been a key species sought for exhibition in zoological gardens across the world since the late 18th century. Cultural depictions of lions were prominent in the Upper Paleolithic period; carvings and paintings from the Lascaux and Chauvet Caves in France have been dated to 17,000 years ago, and depictions have occurred in virtually all ancient and medieval cultures that coincided with the lion's former and current ranges

Etymology

The word 'lion' is derived from Latin: leo[4] and Ancient Greek: λέων (leon).[5] The word lavi (Hebrew: לָבִיא‎) may also be related.[6] The generic name Panthera is traceable to the classical Latin word 'panthēra' and the ancient Greek word πάνθηρ 'panther'.[7] Panthera is phonetically similar to the Sanskrit word पाण्डर pând-ara meaning 'pale yellow, whitish, white'.[8]

Taxonomy

Felis leo was the scientific name used by Carl Linnaeus in 1758, who described the lion in his work Systema Naturae.[3] The genus name Panthera was coined by German naturalist Lorenz Oken in 1816.[13] Between the mid-18th and mid-20th centuries, 26 lion specimens were described and proposed as subspecies, of which 11 were recognised as valid in 2005.[1] They were distinguished on the basis of appearance, size and colour of mane. Because these characteristics show much variation between individuals, most of these forms were probably not true subspecies, especially because they were often based upon museum material with "striking, but abnormal" morphological characteristics.[14]

Subspecies

In the 19th and 20th centuries, several lion type specimens were described and proposed as subspecies, with about a dozen recognised as valid taxa until 2017.[1] Between 2008 and 2016, IUCN Red List assessors used only two subspecific names: P. l. leo for African lion populations and P. l. persica for the Asiatic lion population.[2][15][16] In 2017, the Cat Classification Task Force of the Cat Specialist Group revised lion taxonomy, and recognises two subspecies based on results of several phylogeographic studies on lion evolution, namely:[17]

P. l. leo (Linnaeus, 1758) − the nominate lion subspecies includes the Asiatic lion, the regionally extinct Barbary lion, and lion populations in West and northern parts of Central Africa.[17] Synonyms include P. l. persica (Meyer, 1826), P. l. senegalensis (Meyer, 1826), P. l. kamptzi (Matschie, 1900), and P. l. azandica (Allen, 1924).[1] Some authors referred to it as 'northern lion' and 'northern subspecies'.[18][19]

P. l. melanochaita (Smith, 1842) − includes the extinct Cape lion and lion populations in East and Southern African regions.[17] Synonyms include P. l. somaliensis (Noack 1891), P. l. massaica (Neumann, 1900), P. l. sabakiensis (Lönnberg, 1910), P. l. bleyenberghi (Lönnberg, 1914), P. l. roosevelti (Heller, 1914), P. l. nyanzae (Heller, 1914), P. l. hollisteri (Allen, 1924), P. l. krugeri (Roberts, 1929), P. l. vernayi (Roberts, 1948), and P. l. webbiensis (Zukowsky, 1964).[1][20] It has been referred to as 'southern subspecies' and 'southern lion'.[19]

Lion samples from some parts of the Ethiopian Highlands cluster genetically with those from Cameroon and Chad, while lions from other areas of Ethiopia cluster with samples from East Africa. Researchers therefore assume that Ethiopia is a contact zone between the two subspecies.[21]

Fossil records

Other lion subspecies or sister species to the modern lion existed in prehistoric times:[22]

P. l. sinhaleyus was a fossil carnassial excavated in Sri Lanka, which was attributed to a lion. It is thought to have become extinct around 39,000 years ago.[23]

P. leo fossilis, P. fossilis or P. spelaea fossilis was larger than the modern lion and lived in the Middle Pleistocene. Bone fragments were excavated in caves in the United Kingdom, Germany, Italy and Czech Republic.[24][25]

Panthera spelaea lived in Eurasia and Beringia during the Late Pleistocene. It became extinct due to climate warming latest by 11,900 years ago.[26] Bone fragments excavated in European, North Asian, Canadian and Alaskan caves indicate that it ranged from Europe across Siberia into western Alaska.[27] It likely derived from P. fossilis,[28] and was genetically isolated and highly distinct from the lion in Africa and Asia.[29][28] It is depicted in Paleolithic cave paintings, ivory carvings, and clay busts.[30]

P. l. atrox or P. atrox ranged in the Americas from Canada to possibly Patagonia.[31][31] The American lion arose when a cave lion population in Beringia became isolated south of the Cordilleran Ice Sheet about 370,000 years ago.[32][33] A fossil from Edmonton dates to 11,355 ± 55 years ago.[34]

Evolution

The lion's closest relatives are the other species of the genus Panthera, namely tiger, snow leopard, jaguar, and leopard. Results of phylogenetic studies published in 2006 and 2009 indicate that the jaguar and the lion belong to one sister group that diverged about 2.06 million years ago.[9][10] Results of later studies indicate that the leopard and the lion belong to the same sister group, which diverged 3.1–1.95 million years ago.[11][12] The geographic origin of the Panthera is most likely northern Central Asia. The leopard-lion clade was distributed in the Asian and African Palearctic since at least the Early Pliocene. The lion is thought to have diverged from the cave lion clade in Holarctic Asia or Africa in the Pliocene,[35] around 1.89 million years ago.[28] Hybridisation between ancestors of lion and snow leopard lineages may have continued until about 2.1 million years ago.[36] The Eurasian and American cave lions became extinct at the end of the last glacial period without mitochondrial descendants on other continents.[29][37][38]

The modern lion was probably widely distributed in Africa during the Middle Pleistocene and started to diverge in sub-Saharan Africa during the Late Pleistocene. Lion populations in East and Southern Africa became separated from populations in West and North Africa when the equatorial rainforest expanded 183,500–81,800 years ago. The expansion of the Sahara 83,100–26,600 years ago caused the separation of populations in West and North Africa. As the rainforest decreased, thus giving rise to more open habitats, lions moved from West to Central Africa. Lions from North Africa dispersed to southern Europe and Asia 38,800–8,300 ago.[39] Extinction of lions in southern Europe, North Africa and the Middle East interrupted gene flow between lion populations in Asia and Africa. Genetic evidence revealed numerous mutations in lion samples from East and Southern Africa, which indicates that this group has a longer evolutionary history than genetically less diverse lion samples from Asia and West and Central Africa.[40] Results of phylogeographic research indicate that the two living lion subspecies diverged about 245,000 years ago.[21]

Hybrids

In zoos, lions have been bred with tigers to create hybrids for the curiosity of visitors or for scientific purpose.[41][42] The liger is bigger than a lion and a tiger, whereas most tigons are relatively small compared to their parents because of reciprocal gene effects.[43][44] The leopon is a hybrid between a lion and leopard.[45]

Tiger

Tiger

The tiger (Panthera tigris) is the largest species among the Felidae and classified in the genus Panthera. It is most recognisable for its dark vertical stripes on orangish-brown fur with a lighter underside. It is an apex predator, primarily preying on ungulates such as deer and wild boar. It is territorial and generally a solitary but social predator, requiring large contiguous areas of habitat, which support its requirements for prey and rearing of its offspring. Tiger cubs stay with their mother for about two years, before they become independent and leave their mother's home range to establish their own.

The tiger once ranged widely from the Eastern Anatolia Region in the west to the Amur River basin, and in the south from the foothills of the Himalayas to Bali in the Sunda islands. Since the early 20th century, tiger populations have lost at least 93% of their historic range and have been extirpated in Western and Central Asia, from the islands of Java and Bali, and in large areas of Southeast and South Asia and China. Today's tiger range is fragmented, stretching from Siberian temperate forests to subtropical and tropical forests on the Indian subcontinent and Sumatra.

The tiger is listed as Endangered on the IUCN Red List since 1986. As of 2015, the global wild tiger population was estimated to number between 3,062 and 3,948 mature individuals, down from around 100,000 at the start of the 20th century, with most remaining populations occurring in small pockets isolated from each other. Major reasons for population decline include habitat destruction, habitat fragmentation and poaching. This, coupled with the fact that it lives in some of the more densely populated places on Earth, has caused significant conflicts with humans.

The tiger is among the most recognisable and popular of the world's charismatic megafauna. It featured prominently in ancient mythology and folklore and continues to be depicted in modern films and literature, appearing on many flags, coats of arms and as mascots for sporting teams. The tiger is the national animal of India, Bangladesh, Malaysia and South Korea.

Etymology

The Middle English tigre and Old English tigras (plural)[4] derive from Old French tigre, from Latin tigris. This was a borrowing of Classical Greek τίγρις 'tigris', a foreign borrowing of unknown origin meaning 'tiger' as well as the river Tigris.[5] The origin may have been the Persian word tigra meaning 'pointed or sharp', and the Avestan word tigrhi 'arrow', perhaps referring to the speed of the tiger's leap, although these words are not known to have any meanings associated with tigers.[6]

The generic name Panthera is traceable to the Old French word 'pantère', the Latin word panthera, and the Ancient Greek word πάνθηρ 'panther'.[7] The Sanskrit word पाण्डर pând-ara means 'pale yellow, whitish, white'.[8]

Taxonomy and genetics

In 1758, Carl Linnaeus described the tiger in his work Systema Naturae and gave it the scientific name Felis tigris.[2] In 1929, the British taxonomist Reginald Innes Pocock subordinated the species under the genus Panthera using the scientific name Panthera tigris.[9][10]

Subspecies

Following Linnaeus's first descriptions of the species, several tiger specimens were described and proposed as subspecies.[12] The validity of several tiger subspecies was questioned in 1999. Most putative subspecies described in the 19th and 20th centuries were distinguished on basis of fur length and colouration, striping patterns and body size, hence characteristics that vary widely within populations. Morphologically, tigers from different regions vary little, and gene flow between populations in those regions is considered to have been possible during the Pleistocene. Therefore, it was proposed to recognize only two tiger subspecies as valid, namely P. t. tigris in mainland Asia, and P. t. sondaica in the Greater Sunda Islands.[13]

Results of craniological analysis of 111 tiger skulls from Southeast Asian range countries indicate that Sumatran tiger skulls differ from Indochinese and Javan tiger skulls, whereas Bali tiger skulls are similar in size to Javan tiger skulls. The authors proposed to classify Sumatran and Javan tiger as distinct species, P. sumatrae and P. sondaica with Bali tiger as subspecies P. sondaica balica.[14]

In 2015, morphological, ecological and molecular traits of all putative tiger subspecies were analysed in a combined approach. Results support distinction of the two evolutionary groups continental and Sunda tigers. The authors proposed recognition of only two subspecies, namely P. t. tigris comprising the Bengal, Malayan, Indochinese, South Chinese, Siberian and Caspian tiger populations, and P. t. sondaica comprising the Javan, Bali and Sumatran tiger populations. The authors also noted that this reclassification will affect tiger conservation management. The nominate subspecies P. t. tigris constitutes two clades:[15]

a northern clade composed of the Siberian and Caspian tiger populations

a southern clade composed of all other mainland populations.

One conservation specialist welcomed this proposal as it would make captive breeding programmes and future rewilding of zoo-born tigers easier. One geneticist was sceptical of this study and maintained that the currently recognised nine subspecies can be distinguished genetically.[16]

In 2017, the Cat Classification Task Force of the IUCN Cat Specialist Group revised felid taxonomy and recognized the tiger populations in continental Asia as P. t. tigris, and those in the Sunda Islands as P. t. sondaica.[17] The following tables are based on the classification of the species Panthera tigris provided in Mammal Species of the World.[12] It also reflects the classification used by the Cat Classification Task Force in 2017:

بروكلين ناين-ناين

بروكلين ناين-ناين

بروكلين ناين-ناين (بالإنجليزية: Brooklyn Nine-Nine) مُسلسل كوميدي أمريكي يعرض على قناة فوكس، بدأ عرضه في 17 أيلول، 2013، شاهد الحلقة الاولى 6.17 مليون مشاهد. فاز المسلسل بجائزتي إيمي و جائزتين غولدن غلوب. في 7 مارس، 2014، جُدد المسلسل لموسم ثاني بدأ عرضه في 28 سبتمبر، 2014. وفي 17 يناير، 2015، جدد لموسم ثالث بدأ عرضه في 27 سبتمبر، 2015، وايضاً جدد لموسم رابع في 24 مارس، 2016. وايضاً جدد لموسم خامس في 2017 وانتهى بنفس السنة وثم جدد لموسم سادس مستمر

Brooklyn 99

Brooklyn 99

Brooklyn Nine-Nine is an American police procedural comedy television series created by Dan Goor and Michael Schur. The series revolves around Jake Peralta (Andy Samberg), an immature but talented NYPD detective in Brooklyn's fictional 99th Precinct, who often comes into conflict with his new commanding officer, the serious and stern Captain Raymond Holt (Andre Braugher). The rest of the cast features Stephanie Beatriz as Rosa Diaz, Terry Crews as Terry Jeffords, Melissa Fumero as Amy Santiago, Joe Lo Truglio as Charles Boyle, Chelsea Peretti as Gina Linetti, Dirk Blocker as Michael Hitchcock, and Joel McKinnon Miller as Norm Scully.

Produced as a single-camera comedy, Fox originally ordered 13 episodes for its first season, eventually expanding it to 22 episodes. Brooklyn Nine-Nine premiered on September 17, 2013. On May 10, 2018, Fox canceled the series after five seasons. The following day, NBC picked up the series for a sixth season; it premiered on NBC on January 10, 2019. On February 27, NBC renewed the series for a seventh season, which premiered on February 6, 2020. The series was renewed for an eighth season in November 2019, ahead of the premiere of its seventh season.

The series has been acclaimed by critics for its cast, especially Samberg, Beatriz, Fumero, and Braugher. It has won two Creative Arts Emmy Awards and a Golden Globe Award for Best Television Series – Musical or Comedy. Samberg has won a Golden Globe Award for Best Actor – Television Series Musical or Comedy, while Braugher has been nominated for three consecutive Primetime Emmy Awards for Outstanding Supporting Actor in a Comedy Series and has won two Critics' Choice Television Awards for Best Supporting Actor in a Comedy Series. The series has also received particular praise for its portrayal of serious issues whilst retaining a sense of humor. For its portrayal of LGBTQ+ people, the series won a GLAAD Media Award for Outstanding Comedy Series.

Premise

Set in the fictional 99th Precinct of the New York City Police Department in Brooklyn, Brooklyn Nine-Nine follows a team of detectives headed by the overly serious, newly appointed Captain Raymond Holt (Andre Braugher). The detectives include Jake Peralta (Andy Samberg), who has a high rate of successful arrests and solved cases, in spite of his relaxed, carefree and (at times) childish attitude. He eventually falls for his stern, nerdy, by-the-book but loveable partner, Amy Santiago (Melissa Fumero). The hard-working but timid Charles Boyle (Joe Lo Truglio) is partnered with the stoic, aggressive and stern, Rosa Diaz (Stephanie Beatriz). The pair of older Detectives, Michael Hitchcock (Dirk Blocker) and Norm Scully (Joel McKinnon Miller) often seem incompetent, stupid and lazy, but have solved more cases over the years simply because they have been on the job much longer.

The detectives report to Lieutenant Terry Jeffords (Terry Crews), a gentle giant and devoted family man who initially has a phobia of going back to active field police work for fear of being killed in the line of duty and leaving his children fatherless. The precinct also includes sarcastic and dominating civilian administrator Gina Linetti (Chelsea Peretti), who dislikes her job, prioritizes her social media, and believes that dancing is her life goal.

Cast and characters

See also: List of Brooklyn Nine-Nine characters

Andy Samberg as Jake Peralta

Stephanie Beatriz as Rosa Diaz

Terry Crews as Terry Jeffords

Melissa Fumero as Amy Santiago

Joe Lo Truglio as Charles Boyle

Chelsea Peretti as Gina Linetti (main season 1–6)[a]

Andre Braugher as Raymond Holt

Dirk Blocker as Michael Hitchcock (main season 2–present, recurring season 1)

Joel McKinnon Miller as Norm Scully (main season 2–present, recurring season 1)

Notes

 Chelsea Peretti is credited as a series regular from 1x01 through 6x04. She is credited as a special guest star in 6x15.

Development and production

Michael Schur and Dan Goor, who had known each other since their time as students at Harvard and had collaborated on Parks and Recreation, liked the idea of setting a comedy in a police station, a setting which they felt was insufficiently used for television comedies since Barney Miller. They pitched the idea to Universal Television, where Schur had a development deal. Although Universal agreed to produce the show, NBC passed on airing it, so the duo sold the series to the Fox Broadcasting Company.[1]

On May 8, 2013, Fox placed a thirteen-episode order for the single-camera ensemble comedy.[2][3][4] On October 18, 2013, the series was picked up for a full season of 22 episodes, and was later chosen to air with New Girl in a "special one-hour comedy event" as the Super Bowl XLVIII lead-out programs.[5]

The exterior view of the fictional 99th Precinct building is the actual 78th Precinct building at the corner of Sixth Avenue and Bergen Street. It is one block south of the Barclays Center and one block east of the Bergen Street station on the New York City Subway's 2, ​3, and ​4 routes.[6]

On May 10, 2018, Fox canceled the series after five seasons.[7] Shortly afterwards, there were announcements that negotiations had begun with Hulu, TBS, NBC and Netflix for the possibility of reviving the show for a sixth season.[8] The next day, TVLine reported Hulu had already passed on the series.[9] Shortly after, Goor announced that NBC would pick up the series for thirteen episodes.[10] In a statement, NBC Entertainment chairman Robert Greenblatt expressed regret for originally passing on the series to Fox and was "thrilled" at its addition to NBC.[11][12] A few days later, it was announced that the series would premiere mid-season in the 2018–19 television season.[13] In September 2018, NBC ordered an additional five episodes for season 6, bringing the order to 18.[14] The sixth season began on NBC on January 10, 2019.[15] On February 27, 2019, NBC renewed the series for a seventh season, which premiered on February 6, 2020.[16][17] On November 14, 2019, NBC renewed the series for an eighth season ahead of the seventh-season premiere

Time

Time

Time is the indefinite continued progress of existence and events that occur in an apparently irreversible succession from the past, through the present, into the future.[1][2][3] Time is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience.[4][5][6][7] Time is often referred to as a fourth dimension, along with three spatial dimensions.[8]

Time has long been an important subject of study in religion, philosophy, and science, but defining it in a manner applicable to all fields without circularity has consistently eluded scholars.[2][6][7][9][10][11] Nevertheless, diverse fields such as business, industry, sports, the sciences, and the performing arts all incorporate some notion of time into their respective measuring systems.[12][13][14]

Time in physics is operationally defined as "what a clock reads".[6][15][16] See Units of Time. Time is one of the seven fundamental physical quantities in both the International System of Units and International System of Quantities. Time is used to define other quantities – such as velocity – so defining time in terms of such quantities would result in circularity of definition.[17] An operational definition of time, wherein one says that observing a certain number of repetitions of one or another standard cyclical event (such as the passage of a free-swinging pendulum) constitutes one standard unit such as the second, is highly useful in the conduct of both advanced experiments and everyday affairs of life. To describe observations of an event, a location (position in space) and time are typically noted.

The operational definition of time does not address what the fundamental nature of it is. It does not address why events can happen forward and backwards in space, whereas events only happen in the forward progress of time. Investigations into the relationship between space and time led physicists to define the spacetime continuum. General Relativity is the primary framework for understanding how spacetime works. Through advances in both theoretical and experimental investigations of space-time, it has been shown that time can be distorted, particularly at the edges of black holes.

Temporal measurement has occupied scientists and technologists, and was a prime motivation in navigation and astronomy. Periodic events and periodic motion have long served as standards for units of time. Examples include the apparent motion of the sun across the sky, the phases of the moon, the swing of a pendulum, and the beat of a heart. Currently, the international unit of time, the second, is defined by measuring the electronic transition frequency of caesium atoms (see below). Time is also of significant social importance, having economic value ("time is money") as well as personal value, due to an awareness of the limited time in each day and in human life spans.

Temporal measurement

Generally speaking, methods of temporal measurement, or chronometry, take two distinct forms: the calendar, a mathematical tool for organising intervals of time,[18] and the clock, a physical mechanism that counts the passage of time. In day-to-day life, the clock is consulted for periods less than a day whereas the calendar is consulted for periods longer than a day. Increasingly, personal electronic devices display both calendars and clocks simultaneously. The number (as on a clock dial or calendar) that marks the occurrence of a specified event as to hour or date is obtained by counting from a fiducial epoch – a central reference point.

History of the calendar

Artifacts from the Paleolithic suggest that the moon was used to reckon time as early as 6,000 years ago.[19] Lunar calendars were among the first to appear, with years of either 12 or 13 lunar months (either 354 or 384 days). Without intercalation to add days or months to some years, seasons quickly drift in a calendar based solely on twelve lunar months. Lunisolar calendars have a thirteenth month added to some years to make up for the difference between a full year (now known to be about 365.24 days) and a year of just twelve lunar months. The numbers twelve and thirteen came to feature prominently in many cultures, at least partly due to this relationship of months to years. Other early forms of calendars originated in Mesoamerica, particularly in ancient Mayan civilization. These calendars were religiously and astronomically based, with 18 months in a year and 20 days in a month, plus five epagomenal days at the end of the year.[20]

The reforms of Julius Caesar in 45 BC put the Roman world on a solar calendar. This Julian calendar was faulty in that its intercalation still allowed the astronomical solstices and equinoxes to advance against it by about 11 minutes per year. Pope Gregory XIII introduced a correction in 1582; the Gregorian calendar was only slowly adopted by different nations over a period of centuries, but it is now by far the most commonly used calendar around the world.

During the French Revolution, a new clock and calendar were invented in an attempt to de-Christianize time and create a more rational system in order to replace the Gregorian calendar. The French Republican Calendar's days consisted of ten hours of a hundred minutes of a hundred seconds, which marked a deviation from the base 12 (duodecimal) system used in many other devices by many cultures. The system was abolished in 1806.[21]

History of time measurement devices

A large variety of devices have been invented to measure time. The study of these devices is called horology.[22]

An Egyptian device that dates to c. 1500 BC, similar in shape to a bent T-square, measured the passage of time from the shadow cast by its crossbar on a nonlinear rule. The T was oriented eastward in the mornings. At noon, the device was turned around so that it could cast its shadow in the evening direction.[23]

A sundial uses a gnomon to cast a shadow on a set of markings calibrated to the hour. The position of the shadow marks the hour in local time. The idea to separate the day into smaller parts is credited to Egyptians because of their sundials, which operated on a duodecimal system. The importance of the number 12 is due to the number of lunar cycles in a year and the number of stars used to count the passage of night.[24]

The most precise timekeeping device of the ancient world was the water clock, or clepsydra, one of which was found in the tomb of Egyptian pharaoh Amenhotep I. They could be used to measure the hours even at night, but required manual upkeep to replenish the flow of water. The Ancient Greeks and the people from Chaldea (southeastern Mesopotamia) regularly maintained timekeeping records as an essential part of their astronomical observations. Arab inventors and engineers in particular made improvements on the use of water clocks up to the Middle Ages.[25] In the 11th century, Chinese inventors and engineers invented the first mechanical clocks driven by an escapement mechanism.

The hourglass uses the flow of sand to measure the flow of time. They were used in navigation. Ferdinand Magellan used 18 glasses on each ship for his circumnavigation of the globe (1522).[26]

Incense sticks and candles were, and are, commonly used to measure time in temples and churches across the globe. Waterclocks, and later, mechanical clocks, were used to mark the events of the abbeys and monasteries of the Middle Ages. Richard of Wallingford (1292–1336), abbot of St. Alban's abbey, famously built a mechanical clock as an astronomical orrery about 1330.[27][28]

Great advances in accurate time-keeping were made by Galileo Galilei and especially Christiaan Huygens with the invention of pendulum driven clocks along with the invention of the minute hand by Jost Burgi.[29]

The English word clock probably comes from the Middle Dutch word klocke which, in turn, derives from the medieval Latin word clocca, which ultimately derives from Celtic and is cognate with French, Latin, and German words that mean bell. The passage of the hours at sea were marked by bells, and denoted the time (see ship's bell). The hours were marked by bells in abbeys as well as at sea.

Clocks can range from watches, to more exotic varieties such as the Clock of the Long Now. They can be driven by a variety of means, including gravity, springs, and various forms of electrical power, and regulated by a variety of means such as a pendulum.

Alarm clocks first appeared in ancient Greece around 250 BC with a water clock that would set off a whistle. This idea was later mechanized by Levi Hutchins and Seth E. Thomas.[29]

A chronometer is a portable timekeeper that meets certain precision standards. Initially, the term was used to refer to the marine chronometer, a timepiece used to determine longitude by means of celestial navigation, a precision firstly achieved by John Harrison. More recently, the term has also been applied to the chronometer watch, a watch that meets precision standards set by the Swiss agency COSC.

The most accurate timekeeping devices are atomic clocks, which are accurate to seconds in many millions of years,[31] and are used to calibrate other clocks and timekeeping instruments.

Atomic clocks use the frequency of electronic transitions in certain atoms to measure the second. One of the atoms used is caesium, most modern atomic clocks probe caesium with microwaves to determine the frequency of these electron vibrations.[32] Since 1967, the International System of Measurements bases its unit of time, the second, on the properties of caesium atoms. SI defines the second as 9,192,631,770 cycles of the radiation that corresponds to the transition between two electron spin energy levels of the ground state of the 133Cs atom.

Today, the Global Positioning System in coordination with the Network Time Protocol can be used to synchronize timekeeping systems across the globe.

In medieval philosophical writings, the atom was a unit of time referred to as the smallest possible division of time. The earliest known occurrence in English is in Byrhtferth's Enchiridion (a science text) of 1010–1012,[33] where it was defined as 1/564 of a momentum (1½ minutes),[34] and thus equal to 15/94 of a second. It was used in the computus, the process of calculating the date of Easter.

As of May 2010, the smallest time interval uncertainty in direct measurements is on the order of 12 attoseconds (1.2 × 10−17 seconds), about 3.7 × 1026 Planck times.[35]

Units of time

The second (s) is the SI base unit. A minute (min) is 60 seconds in length, and an hour is 60 minutes in length. A day is 24 hours or 86,400 seconds in length.

Definitions and standards

The Mean Solar Time system defines the second as 1/86,400 of the mean solar day, which is the year-average of the solar day. The solar day is the time interval between two successive solar noons, i.e., the time interval between two successive passages of the Sun across the local meridian. The local meridian is an imaginary line that runs from celestial north pole to celestial south pole passing directly over the head of the observer. At the local meridian the Sun reaches its highest point on its daily arc across the sky.

In 1874 the British Association for the Advancement of Science introduced the CGS (centimetre/gramme/second system) combining fundamental units of length, mass and time. The second is "elastic", because tidal friction is slowing the earth's rotation rate. For use in calculating ephemerides of celestial motion, therefore, in 1952 astronomers introduced the "ephemeris second", currently defined as

the fraction 1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.[36]

The CGS system has been superseded by the Système international. The SI base unit for time is the SI second. The International System of Quantities, which incorporates the SI, also defines larger units of time equal to fixed integer multiples of one second (1 s), such as the minute, hour and day. These are not part of the SI, but may be used alongside the SI. Other units of time such as the month and the year are not equal to fixed multiples of 1 s, and instead exhibit significant variations in duration.[37]

The official SI definition of the second is as follows:[37][38]

The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.

At its 1997 meeting, the CIPM affirmed that this definition refers to a caesium atom in its ground state at a temperature of 0 K.[37]

The current definition of the second, coupled with the current definition of the meter, is based on the special theory of relativity, which affirms our spacetime to be a Minkowski space. The definition of the second in mean solar time, however, is unchanged.

World time

While in theory, the concept of a single worldwide universal time-scale may have been conceived of many centuries ago, in practicality the technical ability to create and maintain such a time-scale did not become possible until the mid-19th century. The timescale adopted was Greenwich Mean Time, created in 1847. A few countries have replaced it with Coordinated Universal Time, UTC.

History of the development of UTC

With the advent of the industrial revolution, a greater understanding and agreement on the nature of time itself became increasingly necessary and helpful. In 1847 in Britain, Greenwich Mean Time (GMT) was first created for use by the British railways, the British navy, and the British shipping industry. Using telescopes, GMT was calibrated to the mean solar time at the Royal Observatory, Greenwich in the UK.

As international commerce continued to increase throughout Europe, in order to achieve a more efficiently functioning modern society, an agreed upon, and highly accurate international standard of time measurement became necessary. In order to find or determine such a time-standard, three steps had to be followed:

An internationally agreed upon time-standard had to be defined.

This new time-standard then had to be consistently and accurately measured.

The new time-standard then had to be freely shared and distributed around the world.

The development of what is now known as UTC time began as a collaboration between 41 nations, officially agreed and signed at the International Meridian Conference, in Washington D.C. in 1884. At this conference, the local mean solar time at the Royal Observatory, Greenwich in England was chosen to define the "universal day", counted from 0 hours at Greenwich mean midnight. This agreed with the civil Greenwich Mean Time used on the island of Great Britain since 1847. In contrast astronomical GMT began at mean noon, i.e. astronomical day X began at noon of civil day X. The purpose of this was to keep one night's observations under one date. The civil system was adopted as of 0 hours (civil) 1 January 1925. Nautical GMT began 24 hours before astronomical GMT, at least until 1805 in the Royal Navy, but persisted much later elsewhere because it was mentioned at the 1884 conference. In 1884, the Greenwich meridian was used for two-thirds of all charts and maps as their Prime Meridian.[39]

Among the 41 nations represented at the conference, the advanced time-technologies that had already come into use in Britain were fundamental components of the agreed method of arriving at a universal and agreed international time. In 1928 Greenwich Mean Time was rebranded for scientific purposes by the International Astronomical Union as Universal Time (UT). This was to avoid confusion with the previous system in which the day had begun at noon. As the general public had always begun the day at midnight, the timescale continued to be presented to them as Greenwich Mean Time. By 1956, universal time had been split into various versions: UT2, which smoothed for polar motion and seasonal effects, was presented to the public as Greenwich Mean Time. Later, UT1 (which smooths only for polar motion) became the default form of UT used by astronomers and hence the form used in navigation, sunrise and sunset and moonrise and moonset tables where the name Greenwich Mean Time continues to be employed. Greenwich Mean Time is also the preferred method of describing the timescale used by legislators. Even to the present day, UT is still based on an international telescopic system. Observations at the Greenwich Observatory itself ceased in 1954, though the location is still used as the basis for the coordinate system. Because the rotational period of Earth is not perfectly constant, the duration of a second would vary if calibrated to a telescope-based standard like GMT, where the second is defined as 1/86 400 of the mean solar day.

Until 1960, the methods and definitions of time-keeping that had been laid out at the International Meridian Conference proved to be adequate to meet time tracking needs of science. Still, with the advent of the "electronic revolution" in the latter half of the 20th century, the technologies that had been available at the time of the Convention of the Metre proved to be in need of further refinement in order to meet the needs of the ever-increasing precision that the "electronic revolution" had begun to require.

The ephemeris second

An invariable second (the "ephemeris second") had been defined, use of which removed the errors in ephemerides resulting from the use of the variable mean solar second as the time argument. In 1960 this ephemeris second was made the basis of the "coordinated universal time" which was being derived from atomic clocks. It is a specified fraction of the mean tropical year as at 1900 and, being based on historical telescope observations, corresponds roughly to the mean solar second of the early nineteenth century.[40]

The SI second

In 1967 a further step was taken with the introduction of the SI second, essentially the ephemeris second as measured by atomic clocks and formally defined in atomic terms.[41] The SI second (Standard Internationale second) is based directly on the measurement of the atomic-clock observation of the frequency oscillation of caesium atoms. It is the basis of all atomic timescales, e.g. coordinated universal time, GPS time, International Atomic Time, etc. Atomic clocks do not measure nuclear decay rates, which is a common misconception, but rather measure a certain natural vibrational frequency of caesium-133.[42] Coordinated universal time is subject to one constraint which does not affect the other atomic timescales. As it has been adopted as the civil timescale by some countries (most countries have opted to retain mean solar time) it is not permitted to deviate from GMT by more than 0.9 second. This is achieved by the occasional insertion of a leap second.

Current application of UTC

Most countries use mean solar time. Australia, Canada (Quebec only), Colombia, France, Germany, New Zealand, Papua New Guinea (Bougainville only), Paraguay, Portugal, Switzerland, the United States and Venezuela use UTC. However, UTC is widely used by the scientific community in countries where mean solar time is official. UTC time is based on the SI second, which was first defined in 1967, and is based on the use of atomic clocks. Some other less used but closely related time-standards include International Atomic Time (TAI), Terrestrial Time, and Barycentric Dynamical Time.

Between 1967 and 1971, UTC was periodically adjusted by fractional amounts of a second in order to adjust and refine for variations in mean solar time, with which it is aligned. After 1 January 1972, UTC time has been defined as being offset from atomic time by a whole number of seconds, changing only when a leap second is added to keep radio-controlled clocks synchronized with the rotation of the Earth.

The Global Positioning System also broadcasts a very precise time signal worldwide, along with instructions for converting GPS time to UTC. GPS-time is based on, and regularly synchronized with or from, UTC-time.

The surface of the Earth is split up into a number of time zones. Most time zones are exactly one hour apart, and by convention compute their local time as an offset from GMT. For example, time zones at sea are based on GMT. In many locations (but not at sea) these offsets vary twice yearly due to daylight saving time transitions.