Customs.

Hinamatsuri is one of the that are held on auspicious dates of the Chinese calendar: the first day of the first month, the third day of the third month, and so on. After the adoption of the Gregorian calendar, these were fixed on 1January, 3March, 5May, 7July, and 9September. The festival was traditionally known as the, as peach trees typically began to flower around this time. Although this is no longer true since the shift to Gregorian dates, the name remains and peaches are still symbolic of the festival.  The primary aspect of Hinamatsuri is the display of seated male and female dolls (the and, literally "male doll" and "female doll" respectively), which represent a Heian period wedding, but usually described as the Emperor and Empress of Japan), usually on red cloth. These may be as simple as pictures or folded paper, or intricately carved three-dimensional dolls. More elaborate displays will include a multi-tiered of dolls that represent ladies of the court, musicians, and other attendants, with all sorts of accoutrements. The entire set of dolls and accessories is called the. The number of tiers and dolls a family may have depends on their budget.  Families normally ensure that girls have a set of the two main dolls before their first Hinamatsuri. The dolls are usually fairly expensive ($1,500 to $2,500 for a five-tier set, depending on quality) and may be handed down from older generations as heirlooms. The "hinakazari" spends most of the year in storage, and girls and their mothers begin setting up the display a few days before 3March (boys normally do not participate, as 5May, now Children's Day was historically called "Boys' Day"). Traditionally, the dolls were supposed to be put away by the day after Hinamatsuri, the superstition being that leaving the dolls any longer will result in a late marriage for the daughter, but some families may leave them up for the entire month of March. Practically speaking, the encouragement to put everything away quickly is to avoid the rainy season and humidity that typically follow Hinamatsuri. Historically, the dolls were used as toys, but in modern times they are intended for display only. The display of dolls usually discontinues when the girls reach 10 years old.  During Hinamatsuri and the preceding days, girls hold parties with their friends. Typical foods include (multi-colored rice crackers), (raw fish and vegetables on rice in a bowl or "bento" box), (multicolored rice cakes), (strawberries wrapped in adzuki bean paste), and (clam soup, as clam shells represent a joined pair). The customary drink is (lit. "white sake"), also called (lit. "sweet sake") a non-alcoholic sake.

Placement.

The actual placement order of the dolls from left to right varies according to family tradition and location, but the order of dolls per level is the same. The layer of covering is called or simply, a red carpet with rainbow stripes at the bottom. The description that follows is for a complete set.

First, top platform.

The top tier holds two dolls, known as. The words "dairi" means "imperial palace". These are the "obina" holding a and "mebina" holding a fan. The pair are also known as and (lord and princess) or and (honored palace official and honored doll). Although they are sometimes referred to as the Emperor and Empress, they only represent the positions and not the actual individuals themselves (with the exception of some dolls from the Meiji period that actually depict Emperor Meiji and Empress Shōken). The two are usually placed in front of a gold folding screen and placed beside green Japanese garden trees.  Optional are the two lampstands, called, and the paper or silk lanterns that are known as, which are usually decorated with cherry or plum blossom patterns.  Complete sets would include accessories placed between the two figures, known as, composing of two vases of artificial.  Generally speaking, the Kansai style arrangement has the male on the right, while Kantō style arrangements have him on the left (from the viewer's perspective).

Second platform.

The second tier holds three court ladies who serve sake to the male and female dolls. Two of them are standing with serving utensils, one with a and the other with a. The, placed in the middle, holds a small table and may be standing or sitting/kneeling.  Accessories placed between the ladies are, stands with round table-tops for seasonal sweets, excluding "hishi mochi".

Third platform.

The third tier holds five male musicians. Each holds a musical instrument except the singer, who holds a fan:  There are ancient sets with seven or ten musicians, and at least one with female musicians.

Fourth platform.

Two may be displayed on the fourth tier. These may be the emperor's bodyguards, or administrators in Kyoto: the and the. Both are sometimes equipped with bows and arrows. When representing the ministers, the Minister of the Right is depicted as a young person, while the Minister of the Left is older because that position was the more senior of the two. Also, because the dolls are placed in positions relative to each other, the Minister of the Right will be on "stage right" (the viewer's left) and the Minister of the Left will be on the other side.  Between the two figures are covered, also referred to as, as well as bearing diamond-shaped "hishi mochi".  Just below the ministers: on the rightmost, a, and on the leftmost, a.

Fifth platform.

The fifth tier, between the plants, holds three or of the Emperor and Empress:

Other platforms.

On the sixth and seventh tiers, a variety of miniature furniture, tools, carriages, etc., are displayed.

Sixth platform.

These are items used within the palatial residence.

Seventh, bottom platform.

These are items used when away from the palatial residence.

Origin.

The earliest record of displaying the dolls as part of the Peach Festival comes from 1625, for Emperor Go-Mizunoo's daughter Oki-ko. Imperial court ladies set up equipment for her to engage in. After Oki-ko succeeded her father as the Empress Meishō, Hinamatsuri legally became the name of the holiday in 1687. Doll-makers began making elaborate dolls for the festival (some growing as tall as 3 feet (1 meter) high before laws were passed restricting their size) and over time, the "hinazakari" evolved to include fifteen dolls and their accessories. As dolls became more expensive, tiers were added to the "hinadan" so that the expensive ones could be placed out of the reach of young children.  During the Meiji period as Japan began to modernize and the emperor was restored to power, Hinamatsuri was deprecated in favor of new holidays that focused on the emperor's supposed bond with the nation, but it was revived. By focusing on marriage and families, it represented Japanese hopes and values, and as the dolls were said to represent the emperor and empress, it also fostered respect for the throne. The holiday then spread to other countries via the Japanese diaspora, although it remains confined to immigrant Japanese communities and their descendants.

, also called Doll's Day or Girls' Day, is a special day in Japan. Celebrated on 3March of each year, platforms covered with a red carpet-material are used to display a set of representing the Emperor, Empress, attendants, and musicians in traditional court dress of the Heian period.

Les jours précédant le, les petites filles japonaises exposent de précieuses poupées posées sur des petites estrades à plusieurs niveaux. Ces poupées spéciales, qui se transmettent parfois de génération en génération, sont rangées dans un carton tout le reste de l'année. Elles représentent des personnages de la cour impériale de l'.


Etymology.

The modern English word "Hebrew" is derived from Old French "Ebrau", via Latin from the Greek "Ἑβραῖος" ("Hebraîos") and Aramaic "'ibrāy", all ultimately derived from Biblical Hebrew "Ivri" (), one of several names for the Israelite (Jewish and Samaritan) people (Hebrews). It is traditionally understood to be an adjective based on the name of Abraham's ancestor, Eber, mentioned in. The name is believed to be based on the Semitic root "ʕ-b-r" () meaning "beyond", "other

History.

Hebrew belongs to the Canaanite group of languages. Canaanite languages are a branch of the Northwest Semitic family of languages.  According to Avraham Ben-Yosef, Hebrew flourished as a spoken language in the Kingdoms of Israel and Judah during the period from about 1200 to 586 BCE. Scholars debate the degree to which Hebrew was a spoken vernacular in ancient times following the Babylonian exile, when the predominant international language in the region was Old Aramaic.  Hebrew was extinct as a colloquial language by Late Antiquity, but it continued to be used as a literary language and as the liturgical language of Judaism, evolving various dialects of literary Medieval Hebrew, until its revival as a spoken language in the late 19th century.

Oldest Hebrew inscriptions.

In July 2008, Israeli archaeologist Yossi Garfinkel discovered a ceramic shard at Khirbet Qeiyafa that he claimed may be the earliest Hebrew writing yet discovered, dating from around 3,000 years ago. Hebrew University archaeologist Amihai Mazar said that the inscription was "proto-Canaanite" but cautioned that "The differentiation between the scripts, and between the languages themselves in that period, remains unclear," and suggested that calling the text Hebrew might be going too far.  The Gezer calendar also dates back to the 10th century BCE at the beginning of the Monarchic Period, the traditional time of the reign of David and Solomon. Classified as Archaic Biblical Hebrew, the calendar presents a list of seasons and related agricultural activities. The Gezer calendar (named after the

Classical Hebrew.

Biblical Hebrew.

In its widest sense, Biblical Hebrew refers to the spoken language of ancient Israel flourishing between the 10th century BCE

Early post-Biblical Hebrew.

Sometimes the above phases of spoken Classical Hebrew are simplified into "Biblical Hebrew" (including several dialects from the 10th century BCE to 2nd century BCE and extant in certain Dead Sea Scrolls) and "Mishnaic Hebrew" (including several dialects from the 3rd century BCE to the 3rd century CE and extant in certain other Dead Sea Scrolls). However, today most Hebrew linguists classify Dead Sea Scroll Hebrew as a set of dialects evolving out of Late Biblical Hebrew and into Mishnaic Hebrew, thus including elements from both but remaining distinct from either.  By the start of the Byzantine Period in the 4th century CE, Classical Hebrew ceased as a regularly spoken language, roughly a century after the publication of the Mishnah, apparently declining since the aftermath of the catastrophic Bar Kokhba War around 135 CE.

Displacement by Aramaic.

In the early 6th century BCE, the Neo-Babylonian Empire conquered the ancient Kingdom of Judah, destroying much of Jerusalem and exiling its population far to the East in Babylon. During the Babylonian captivity, many Israelites learned Aramaic, the closely related Semitic language of their captors. Thus for a significant period, the Jewish elite became influenced by Aramaic.  After Cyrus the Great conquered Babylon, he allowed the Jewish people to return from captivity. As a result, a local version of Aramaic came to be spoken in Israel alongside Hebrew. By the beginning of the Common Era, Aramaic was the primary colloquial language of Samarian, Babylonian and Galileean Jews, and western and intellectual Jews spoke Greek, but a form of so-called Rabbinic Hebrew continued to be used as a vernacular in Judea until it was displaced by Aramaic, probably

Mishnah and Talmud.

The term "Mishnaic Hebrew" generally refers to the Hebrew dialects found in the Talmud, excepting quotations from the Hebrew Bible. The dialects organize into Mishnaic Hebrew (also called Tannaitic Hebrew, Early Rabbinic Hebrew, or Mishnaic Hebrew I), which was a spoken language, and Amoraic Hebrew (also called Late Rabbinic Hebrew or Mishnaic Hebrew II), which was a literary language. The earlier section of the Talmud is the Mishnah that was published around 200 CE, although many of the stories take place much earlier, and was written in the earlier Mishnaic dialect. The dialect is also found in certain Dead Sea Scrolls. Mishnaic Hebrew is considered to be one of the dialects of Classical Hebrew that functioned as a living language in the land of Israel. A transitional form of the language occurs in the other works of Tannaitic literature dating from the century beginning with the

Medieval Hebrew.

After the Talmud, various regional literary dialects of Medieval Hebrew evolved. The most important is Tiberian Hebrew or Masoretic Hebrew, a local dialect of Tiberias in Galilee that became the standard for vocalizing the Hebrew Bible and thus still influences all other regional dialects of Hebrew. This Tiberian Hebrew from the 7th to 10th century CE is sometimes called "Biblical Hebrew" because it is used to pronounce the Hebrew Bible; however, properly it should be distinguished from the historical Biblical Hebrew of the 6th century BCE, whose original pronunciation must be reconstructed. Tiberian Hebrew incorporates the remarkable scholarship of the Masoretes (from "masoret" meaning "tradition"), who added vowel points and grammar points to the

Revival.

Hebrew has been revived several times as a literary language, most significantly by the Haskalah (Enlightenment) movement of early and mid-19th-century Germany. In the early 19th century, a form of spoken Hebrew had emerged in the markets of Jerusalem between Jews of different linguistic backgrounds to communicate for commercial purposes. This Hebrew dialect was to a certain extent a pidgin. Near the end of that century the Jewish activist Eliezer Ben-Yehuda, owing to the ideology of the national revival (, "Shivat Tziyon," later Zionism), began reviving Hebrew as a modern spoken language. Eventually, as a result of the local movement he created, but more significantly as a result of the new groups of immigrants known under the name of the Second Aliyah, it replaced a score of languages spoken by Jews at that time. Those languages were Jewish dialects of local languages, including Judaeo-Spanish (also called "Judezmo" and "Ladino"), Yiddish, Judeo-Arabic and Bukhori (Tajiki), or local languages spoken in the Jewish diaspora such

Modern Hebrew.

Standard Hebrew, as developed by Eliezer Ben-Yehuda, was based on Mishnaic spelling and Sephardi Hebrew pronunciation. However, the earliest speakers of Modern Hebrew had Yiddish as their native language and often introduced calques from Yiddish and phono-semantic matchings of international words.  Despite using Sephardic

Current status.

Modern Hebrew is the primary official language of the State of Israel., there are about 9 million Hebrew speakers worldwide, of whom 7 million speak it fluently.  Currently, 90% of Israeli Jews are proficient in Hebrew, and 70% are highly proficient. Some 60% of Israeli Arabs are also proficient in Hebrew, and 30% report having a higher proficiency in Hebrew than in Arabic. In total, about 53% of the Israeli population speaks Hebrew as a native language, while most of the rest speak it fluently. However, in 2013 Hebrew was the native language of only 49% of Israelis over the age of 20, with Russian, Arabic, French, English, Yiddish and Ladino being the native tongues of most of the rest. Some 26% of immigrants from the former

Phonology.

Biblical Hebrew had a typical Semitic consonant inventory, with pharyngeal /ʕ ħ/, a series of "emphatic" consonants (possibly ejective, but this is debated), lateral fricative /ɬ/, and in its older stages also uvular /χ ʁ/. /χ ʁ/ merged into /ħ ʕ/ in later Biblical Hebrew, and /b ɡ d k p t/ underwent allophonic spirantization to [v ɣ ð x f θ] (known as begadkefat). The earliest Biblical Hebrew vowel system contained the Proto-Semitic vowels /a aː i iː u uː/ as well as /oː/, but this system changed dramatically over time.  By the time of the Dead Sea Scrolls, /ɬ/ had shifted to /s/ in the Jewish traditions, though for the Samaritans it merged with /ʃ/ instead. (Elisha Qimron 1986. "Hebrew of the Dead Sea Scrolls", 29). The Tiberian reading tradition of the Middle Ages had the vowel system /a ɛ e i ɔ o u ă ɔ̆ ɛ̆/, though other Medieval reading traditions had fewer vowels.  A number of reading traditions have been preserved in liturgical use. In Oriental (Sephardi and Mizrahi) Jewish reading traditions, the emphatic consonants are realized as pharyngealized, while the Ashkenazi (northern and eastern European) traditions have lost emphatics and pharyngeals (although according to Ashkenazi law, pharyngeal articulation is preferred over uvular or glottal articulation when representing the community in religious service such as prayer and Torah reading), and show the shift of /w/ to /v/. The Samaritan tradition has a complex vowel system that does not correspond closely to the Tiberian systems.  Modern Hebrew pronunciation developed from a mixture of the different Jewish reading traditions, generally tending towards simplification. In line with Sephardi Hebrew pronunciation, emphatic consonants have shifted to their ordinary counterparts, /w/ to /v/, and [ɣ ð θ] are not present. Most Israelis today also merge /ʕ ħ/ with /ʔ χ/, do not have contrastive gemination, and pronounce /r/ as a uvular fricative [ʁ] or a voiced velar fricative [ɣ] rather than an alveolar trill, because of Ashkenazi Hebrew influences. The consonants /tʃ/ and /dʒ/ have become phonemic due to loan words, and /w/ has similarly been re-introduced.

Consonants.

Hebrew grammar.

Hebrew grammar is partly analytic, expressing such forms as dative, ablative and accusative using prepositional particles rather than grammatical cases. However, inflection plays a decisive role in the formation of the verbs and nouns. For example, nouns have a construct state, called "smikhut", to denote the relationship of "belonging to": this is the converse of the genitive case of more inflected languages. Words in smikhut are often combined with hyphens. In modern speech, the use of the construct is sometimes interchangeable with the preposition "shel", meaning "of". There are many cases, however, where older declined forms are retained (especially in idiomatic expressions and the like), and "person"-enclitics are widely used to "decline" prepositions.

Morphology.

Like all Semitic languages, the Hebrew language exhibits a pattern of stems consisting typically of "triliteral", or 3-consonant consonantal roots, from which nouns, adjectives, and verbs are formed in various ways: e.g. by inserting vowels, doubling consonants, lengthening vowels and/or adding prefixes, suffixes or infixes. 4-consonant roots also exist and became more frequent in the modern language due to a process of coining verbs from nouns that are themselves constructed from 3-consonant verbs. Some trilateral roots lose one of their consonants in most forms and are called "Nehim" (Resting).  Hebrew uses a number of one-letter prefixes that are added to words for various purposes. These are called inseparable prepositions or "Letters of Use" (). Such items include: the definite article "ha-" () (="the"); prepositions "be-" () (="in"), "le-" () (="to"; a shortened version of the preposition "el"), "mi-" () (="from"; a shortened

Syntax.

Like most other languages, the vocabulary of the Hebrew language is divided into verbs,

Writing system.

Modern Hebrew is written from right to left using the Hebrew alphabet, which is an "impure" abjad, or consonant-only script, of 22 letters. The ancient paleo-Hebrew alphabet is similar to those used for Canaanite and Phoenician. Modern scripts are based on the "square" letter form, known as "Ashurit" (Assyrian), which was developed from the Aramaic script. A cursive Hebrew script is used in handwriting: the letters

Liturgical use in Judaism.

Hebrew has always been used as the language of prayer and study, and the following pronunciation systems are found.  Ashkenazi Hebrew, originating in Central and Eastern Europe, is still widely used in Ashkenazi Jewish religious services and studies in Israel and abroad, particularly in the Haredi and other Orthodox communities. It was influenced by the Yiddish language.  Sephardi Hebrew is the traditional pronunciation of the Spanish and Portuguese Jews and Sephardi Jews in the countries of the former Ottoman Empire, with the exception of Yemenite Hebrew. This pronunciation, in the form used by the Jerusalem Sephardic community, is the basis of the Hebrew phonology of Israeli native speakers. It was influenced by the Judezmo language.  Mizrahi (Oriental) Hebrew is actually a collection of dialects spoken liturgically by Jews in various parts of the Arab and Islamic world. It was derived from the old Arabic language, and in some cases influenced by Sephardi Hebrew. The same claim is sometimes made for Yemenite Hebrew or "Temanit", which differs from other Mizrahi dialects by having a radically different vowel system, and distinguishing between different diacritically marked consonants that are pronounced identically in other dialects (for example gimel and "ghimel".)  These pronunciations are still used in synagogue ritual and religious study, in Israel and elsewhere, mostly by people who are not native speakers of Hebrew, though some traditionalist Israelis use liturgical pronunciations in prayer.  Many synagogues in the diaspora, even though Ashkenazi by rite and by ethnic composition, have adopted the "Sephardic" pronunciation in deference to Israeli Hebrew. However, in many British and American schools and synagogues, this pronunciation retains several elements of its Ashkenazi substrate, especially the distinction between tsere and segol.

Hebrew (, or ) is a Northwest Semitic language native to Israel. In 2013, Modern Hebrew was spoken by over nine million people worldwide. Historically, it is regarded as the language of the Israelites and their ancestors, although the language was not referred to by the name "Hebrew" in the Tanakh itself. The earliest examples of written Paleo-Hebrew date from the 10th century BCE. Hebrew belongs to the West Semitic branch of the Afroasiatic language family. Hebrew is the only Canaanite language still spoken and the only truly successful example of a revived dead language.

L’hébreu (en hébreu moderne : / ou, et en hébreu ancien : « langue sacrée ») est une langue chamito-sémitique appartenant à la branche centre-nord de la famille des langues sémitiques du groupe canaanéen. Elle est étroitement apparentée au phénicien et aux langues araméennes ainsi qu'à l'arabe.


Taxonomy.

Research history.

The first recognised remains—OH 7, a partial juvenile skull and hand and foot bones dating to 1.75 million years ago (mya)—were discovered in Olduvai Gorge, Tanzania, in 1960 by Jonathan Leakey. However, the actual first remains—OH 4, a molar—were discovered by the Leakeys' senior assistant Heselon Mukiri in 1959, but this was not realised at the time. By this time, palaeoanthropologists Louis and Mary Leakey (Jonathan's parents) had spent 29 years excavating in Olduvai Gorge for early hominin remains, but had instead recovered mainly other animal remains as well as the Oldowan stone tool industry. The industry had been ascribed to "Paranthropus boisei" (at the time ""Zinjanthropus"") in 1959 as it was the first and only hominin recovered in the area, but this was revised upon OH 7's discovery. In 1964, Louis, South African palaeoanthropologist Phillip V. Tobias, and British primatologist John R. Napier officially assigned the remains into the genus "Homo" as, on recommendation by Australian anthropologist Raymond Dart, "H. habilis", the species name meaning "able, handy, mentally skilful, vigorous" in Latin. The specimen's association with the Oldowan (then considered evidence of advanced cognitive ability) was also used as justification for classifying it into "Homo". OH 7 was designated the holotype specimen.  After description, it was hotly debated if "H. habilis" should be reclassified into "Australopithecus africanus" (the only other early hominin known at the time), in part because the remains were so old and at the time "Homo" was presumed to have evolved in Asia (with the australopithecines having no living descendants), and the brain size was smaller than what Wilfrid Le Gros Clark proposed in 1955 when considering "Homo". The classification "H. habilis" began to receive wider acceptance as more fossil elements and species were being unearthed. In 1983, Tobias proposed that "A. africanus" was a direct ancestor of "Paranthropus" and "Homo" (the two were sister taxa), and that "A. africanus" evolved into "H. habilis" which evolved into "H. erectus" which evolved into modern humans (by a process of cladogenesis). He further said that there was a major evolutionary leap between "A. africanus" and "H. habilis", and thereupon human evolution progressed gradually because "H. habilis" brain size had nearly doubled compared to australopithecine predecessors. However, OH 24, at the time the oldest "H. habilis" specimen, was similar to the younger OH 13, which showed there was no evolutionary progression through the lineage.  Many had accepted Tobias' model and assigned Late Pliocene to Early Pleistocene hominin remains outside the range of "Paranthropus" and "H. erectus" into "H. habilis". For non-skull elements, this was done on the basis of size as there was a lack of clear diagnostic characteristics. Because of these practices, the range of variation for the species became quite wide, and the terms "H. habilis" sensu stricto ("in the strict sense") and "H. habilis" sensu lato ("in the broad sense") were in use to distinguish, respectively, between the Olduvai morph and more discrepant morphs. To address this, in 1985, English palaeoanthropologist Bernard Wood proposed that the comparatively massive skull KNM-ER 1470 from Lake Turkana, Kenya, discovered in 1972 and assigned to "H. habilis", actually represented a different species, now referred to as "Homo rudolfensis", but it is also argued that instead it represents a male specimen whereas other "H. habilis" specimens are female. In 2010, Australian archaeologist Darren Curoe proposed splitting off South African "H. habilis" into a new species, "Homo gautengensis".  In 1986, OH 62, a fragmentary skeleton, was discovered by American anthropologist Tim D. White in association with "H. habilis" skull fragments, definitively establishing "H. habilis" skeletal anatomy for the first time, and revealing more "Australopithecus"-like than "Homo"-like features. Because of this, as well as similarities in dental adaptations, Wood and biological anthropologist Mark Collard suggested moving the species to "Australopithecus" in 1999. However, reevaluation of OH 62 to a more humanlike physiology, if correct, would cast doubt on this. The discovery of the 1.8 Ma Georgian Dmanisi skulls, in the early 2000s, which exhibit several similarities with early "Homo" has led to suggestions that all contemporary groups of early "Homo" in Africa, including "H. habilis" and "H. rudolfensis", are the same species and should be assigned to "H. erectus".

Classification.

There is still no wide consensus as to whether or not "H. habilis" is ancestral to "H. ergaster"/"H. erectus" or is an offshoot of the human line, and whether or not all specimens assigned to "H. habilis" are correctly assigned or the species is an assemblage of different "Australopithecus" and "Homo" species. Nonetheless, "H. habilis" and "H. rudolfensis" generally are recognised members of the genus at the base of the family tree, with arguments for synonymisation or removal from the genus not widely adopted.  Though it is now largely agreed upon that "Homo" evolved from "Australopithecus", the timing and placement of this split has been much debated, with many "Australopithecus" species having been proposed as the ancestor. The discovery of LD 350-1, the oldest "Homo" specimen, dating to 2.8 mya, in the Afar Region of Ethiopia may indicate that the genus evolved from "A. afarensis" around this time. The species LD 350-1 belongs to could be the ancestor of "H. habilis", but this is unclear. The oldest "H. habilis" specimen, A.L. 666-1, dates to 2.3 mya, but is anatomically more derived (features less ancestral, or basal, traits) than the younger OH 7, suggesting derived and basal morphs lived concurrently, and that the "H. habilis" lineage began before 2.3 mya. Based on 2.1 million year old stone tools from Shangchen, China, "H. habilis" or an ancestral species may have dispersed across Asia. The youngest "H. habilis" specimen, OH 13, dates to about 1.65 mya.

Anatomy.

It has generally been thought that brain size increased along the human line especially rapidly at the transition between species, with "H. habilis" brain size smaller than that of "H. ergaster"/"H. erectus", jumping from about in "H. habilis" to about in "H. ergaster" and "H. erectus". However, a 2015 study showed that the brain sizes of "H. habilis", "H. rudolfensis", and "H. ergaster" generally ranged between after reappraising the brain volume of OH 7 from to. This does, nonetheless, indicate a jump from australopithecines brain size which generally ranged from. The brain anatomy of all "Homo" features an expanded cerebrum in comparison to australopithecines. The pattern of striations on the teeth of OH 65 slanting right could indicate right handedness, and handedness is associated with major reorganisation of the brain and the lateralisation of brain function between the left and right hemispheres. This could be implicated in tool use. In modern humans, lateralisation is weakly associated with language. The tooth rows of "H. habilis" were V-shaped as opposed to U-shaped in later "Homo", and the mouth jutted outwards (was prognathic), though the face was flat from the nose up.  Based on the fragmentary skeletons OH 62 (presumed female) and KNM-ER 3735 (presumed male), "H. habilis" body anatomy has generally been considered to have been more apelike than even that of the earlier "A. afarensis" and consistent with an at least partially arboreal lifestyle in the trees as is assumed in australopithecines. Based on OH 62 and assuming comparable body dimensions to australopithecines, "H. habilis" has generally been interpreted as having been small-bodied like australopithecines, with OH 62 generally estimated at about in height and in weight. However, assuming longer, modern humanlike legs, OH 62 would have been about and, and KNM-ER 3735 about the same size. For comparison, modern human men and women in the year 1900 averaged and respectively. It is generally assumed that pre-"H. ergaster" hominins, including "H. habilis", exhibited notable sexual dimorphism with males markedly bigger than females. However, relative female body mass is unknown in this species. Early hominins, including "H. habilis", are thought to have had thick body hair coverage like modern non-human apes because they appear to have inhabited cooler regions and are thought to have had a less active lifestyle than (presumed hairless) post-"ergaster" species, and so probably required thick body hair to stay warm. Based on dental development rates, "H. habilis" is assumed to have had an accelerated growth rate compared to modern humans, more like that of modern non-human apes. The arms of "H. habilis" and australopithecines have generally been considered to have been proportionally long and so adapted for climbing and swinging. However, the humerus to femur ratio of OH 62 and the "A. afarensis" specimen AL 288-1 are both within the range of variation for modern humans, and KNM-ER 3735 is close to the modern human average, so it may be unsafe to assume apelike proportions. Nonetheless, the humerus of OH 62 measured long and the ulna (forearm), which is closer to the proportion seen in chimps. The hand bones of OH 7 suggest precision gripping, important in dexterity, as well as adaptations for climbing. In regard to the femur, traditionally comparisons with AL 288-1 have been used to reconstruct stout legs for "H. habilis", but the more gracile OH 24 femur (either belonging to "H. ergaster"/"H. erectus" or "P. boisei") may be a more apt comparison. In this instance, "H. habilis" would have had longer, humanlike legs and have been effective long-distance travellers as is assumed to have been the case in "H. ergaster". However, estimating the unpreserved length of a fossil is highly problematic. The thickness of the limb bones in OH 62 is more similar to chimps than "H. ergaster"/"H. erectus" and modern humans, which may indicate different load bearing capabilities more suitable for arboreality in "H. habilis". The strong fibula of OH 35 (though this may belong to "P. boisei") is more like that of non-human apes, and consistent with arboreality and vertical climbing. OH 8, a foot, is better suited for terrestrial movement than the foot of "A. afarensis", though still retains many apelike features consistent with climbing. However, the foot has projected toe bone and compacted mid-foot joint structures, which restricts rotation in the hind and front parts of the foot and is implicated in the plantar arch elastic spring mechanism which generates energy while running (but not walking). This could possibly indicate "H. habilis" was capable of some degree of endurance running, which is typically thought to have evolved later in "H. ergaster"/"H. erectus".

Culture.

Society.

Typically, "H. ergaster"/"H. erectus" is considered to have been the first human to have lived in a monogamous society, and all preceding hominins were polygynous. However, it is highly difficult to speculate with accuracy the group dynamics of early hominins. The degree of sexual dimorphism and the size disparity between males and females is often used to correlate between polygyny with a high degree and monogamy with a low degree based on general trends (though not without exceptions) seen in modern primates. Further, early hominin anatomy is poorly known and is largely based on few specimens, and sex has to be arbitrarily determined in large part based on perceived size and apparent robustness in the absence of more reliable elements in sex identification (namely the pelvis). Mating systems are also based on dental anatomy, but early hominins possess a mosaic anatomy of different traits not seen in together in modern primates; the enlarged cheek teeth would suggest marked size-related dimorphism and thus intense male–male conflict over mates and a polygynous society, but the small canines should indicate the opposite. Other selective pressures, including diet, can also dramatically impact dental anatomy.  The behaviour of early "Homo", including "H. habilis", is sometimes modelled on that of savanna chimps and baboons. These communities consist of several males (as opposed to a harem society) in order to defend the group on the dangerous and exposed habitat, sometimes engaging in a group display of throwing sticks and stones against enemies and predators. "H. habilis" and contemporary hominins were likely predated upon by the large carnivores of the time, such as (in Olduvai Gorge) the hunting hyena "Chasmaporthetes nitidula", the leopard, the saber-toothed cats "Dinofelis" and "Megantereon", and possibly crocodiles such as "Crocodylus anthropophagus". In 1993, American palaeoanthropologist Leslie C. Aiello and British evolutionary psychologist Robin Dunbar estimated that "H. habilis" group size ranged from 70–85 members—on the upper end of chimp and baboon group size—based on trends seen in neocortex size and group size in modern non-human primates.  "H. habilis" coexisted with "H. rudolfensis", "H. ergaster"/"H. erectus", and "P. boisei". It is unclear how all of these species interacted. To explain why "P. boisei" was associated with Olduwan tools despite not being the knapper, Leakey and colleagues, when describing "H. habilis", suggested that one possibility was "P. boisei" was killed by "H. habilis", perhaps as food. However, when describing "P. boisei" 5 years earlier, Louis Leakey said, "There is no reason whatever, in this case, to believe that the skull represents the victim of a cannibalistic feast by some hypothetical more advanced type of man."

Diet.

It is typically thought that the diets of "H. habilis" and other early "Homo" had a greater proportion of meat than "Australopithecus", and that this led to brain growth. The main hypotheses regarding this are: meat is energy- and nutrient-rich and put evolutionary pressure on developing enhanced cognitive skills to facilitate strategic scavenging and monopolise fresh carcasses, or meat allowed the large and calorie-expensive ape gut to decrease in size allowing this energy to be diverted to brain growth. Alternatively, it is also suggested that early "Homo", in a drying climate with scarcer food options, relied primarily on underground storage organs (such as tubers) and food sharing, which facilitated social bonding among both male and female group members. However, unlike what is presumed for "H. ergaster" and later "Homo", short-statured early "Homo" are generally considered to have been incapable of endurance running and hunting, and the long and "Australopithecus"-like forearm of "H. habilis" could indicate early "Homo" were still arboreal to a degree. Also, organised hunting and gathering is thought to have emerged in "H. ergaster". Nonetheless, the proposed food-gathering models to explain large brain growth necessitate increased daily travel distance. It has also been argued that "H. habilis" instead had long, modern humanlike legs and was fully capable of effective long distance travel, while still remaining at least partially arboreal.  Large incisor size in "H. habilis" compared to "Australopithecus" predecessors implies this species relied on incisors more. The bodies of the mandibles of "H. habilis" and other early "Homo" are thicker than those of modern humans and all living apes, more comparable to "Australopithecus". The mandibular body resists torsion from the bite force or chewing, meaning their jaws could produce unusually powerful stresses while eating. The greater molar cusp relief in "H. habilis" compared to "Australopithecus" suggests the former used tools to fracture tough foods (such as pliable plant parts or meat), otherwise the cusps would have been more worn down. Nonetheless, the jaw adaptations for processing mechanically challenging food indicates technological advancement did not greatly affect diet.  It is thought "H. habilis" derived meat from scavenging rather than hunting (scavenger hypothesis), acting as a confrontational scavenger and stealing kills from smaller predators such as jackals or cheetahs. Fruit was likely also an important dietary component, indicated by dental erosion consistent with repetitive exposure to acidity. Based on dental microwear-texture analysis, "H. habilis" (like other early "Homo") likely did not regularly consume tough foods. Microwear-texture complexity is, on average, somewhere between that of tough-food eaters and leaf eaters (folivores), and points to an increasingly generalized and omnivorous diet.

Technology.

"H. habilis" is associated with the Early Stone Age Oldowan stone tool industry. Individuals likely used these tools primarily to butcher and skin animals and crush bones, but also sometimes to saw and scrape wood and cut soft plants. Knappers appear to have carefully selected lithic cores and knew that certain rocks would break in a specific way when struck hard enough and on the right spot, and they produced several different types, including choppers, polyhedrons, and discoids. Nonetheless, specific shapes were likely not thought of in advance, and probably stem from a lack of standardisation in producing such tools as well as the types of raw materials at the knappers' disposal. For example, spheroids are common at Olduvai which features an abundance of large quartz and quartzite pieces, whereas Koobi Fora lacks spheroids and provided predominantly basalt lava rocks. Unlike the later Acheulean culture invented by "H. ergaster"/"H. erectus", Oldowan technology does not require planning and foresight to manufacture, and thus does not indicate high cognition in Oldowan knappers, though it does require a degree of coordination and some knowledge of mechanics. Oldowan tools infrequently exhibit retouching and were probably discarded immediately after use.  The Olduwan was first reported in 1934, but it was not until the 1960s that it become widely accepted as the earliest culture, dating to 1.8 mya, and as having been manufactured by "H. habilis". Since then, more discoveries have placed the origins of material culture substantially backwards in time, with the Oldowan being discovered in Ledi-Geraru and Gona in Ethiopia dating to 2.6 mya, perhaps associated with the evolution of the genus. Australopithecines are also known to have manufactured tools, such as the 3.3 Ma Lomekwi stone tool industry, and some evidence of butchering from about 3.4 mya. Nonetheless, the comparatively sharp-edged Oldowan culture was a major innovation from australopithecine technology, and it would have allowed different feeding strategies and the ability to process a wider range of foods, which would have been advantageous in the changing climate of the time. It is unclear if the Oldowan was independently invented or if it was the result of hominin experimentation with rocks over hundreds of thousands of years across multiple species.  In 1962, a circle made with volcanic rocks was discovered in Olduvai Gorge. At intervals, rocks were piled up to high. Mary Leakey suggested the rock piles were used to support poles stuck into the ground, possibly to support a windbreak or a rough hut. Some modern day nomadic tribes build similar low-lying rock walls to build temporary shelters upon, bending upright branches as poles and using grasses or animal hide as a screen. Dating to 1.75 mya, it is the oldest claimed evidence of architecture.

Homo habilis ("handy man") is a species of archaic human from the Early Pleistocene of East and South Africa about 2.3–1.65 million years ago (mya). Upon species description in 1964, "H. habilis" was highly contested, with many researchers recommending it be synonymised with "Australopithecus africanus", the only other early hominin known at the time, but "H. habilis" received more recognition as time went on and more relevant discoveries were made. By the 1980s, "H. habilis" was proposed as being a human ancestor, directly evolving into "Homo erectus" which directly led to modern humans. This viewpoint is now debated. Several specimens with insecure species identification were assigned to "H. habilis", leading to arguments for splitting, namely into ""H. rudolfensis"" and ""H. gautengensis"" of which only the former has received wide support.

Homo habilis (littéralement « homme "habile" ») est une espèce éteinte du genre "Homo" qui, d'après les fossiles trouvés à ce jour, aurait vécu en Afrique de l'Est il y a entre 2,3 et 1,5 millions d’années environ.


History.

Scientific inquiry into the wave nature of light began in the 17th and 18th centuries, when scientists such as Robert Hooke, Christiaan Huygens and Leonhard Euler proposed a wave theory of light based on experimental observations. In 1803, English polymath Thomas Young described the famous double-slit experiment. This experiment played a major role in the general acceptance of the wave theory of light.  In 1838, Michael Faraday discovered cathode rays. These studies were followed by the 1859 statement of the black-body radiation problem by Gustav Kirchhoff, the 1877 suggestion by Ludwig Boltzmann that the energy states of a physical system can be discrete, and the 1900 quantum hypothesis of Max Planck. Planck's hypothesis that energy is radiated and absorbed in discrete "quanta" (or energy packets) precisely matched the observed patterns of black-body radiation.  In 1896, Wilhelm Wien empirically determined a distribution law of black-body radiation, called Wien's law. Ludwig Boltzmann independently arrived at this result by considerations of Maxwell's equations. However, it was valid only at high frequencies and underestimated the radiance at low frequencies.  The foundations of quantum mechanics were established during the first half of the 20th century by Max Planck, Niels Bohr, Werner Heisenberg, Louis de Broglie, Arthur Compton, Albert Einstein, Erwin Schrödinger, Max Born, John von Neumann, Paul Dirac, Enrico Fermi, Wolfgang Pauli, Max von Laue, Freeman Dyson, David Hilbert, Wilhelm Wien, Satyendra Nath Bose, Arnold Sommerfeld, and. The Copenhagen interpretation of Niels Bohr became widely accepted.  Max Planck corrected this model using Boltzmann's statistical interpretation of thermodynamics and proposed what is now called Planck's law, which led to the development of quantum mechanics. After Planck's solution in 1900 to the black-body radiation problem (reported 1859), Albert Einstein offered a quantum-based explanation of the photoelectric effect (1905, reported 1887). Around 1900–1910, the atomic theory but not the corpuscular theory of light first came to be widely accepted as scientific fact; these latter theories can be considered quantum theories of matter and electromagnetic radiation, respectively. However, the photon theory was not widely accepted until about 1915. Even until Einstein's Nobel Prize, Niels Bohr did not believe in the photon.  Among the first to study quantum phenomena were Arthur Compton, C. V. Raman, and Pieter Zeeman, each of whom has a quantum effect named after him. Robert Andrews Millikan studied the photoelectric effect experimentally, and Albert Einstein developed a theory for it. At the same time, Ernest Rutherford experimentally discovered the nuclear model of the atom, and Niels Bohr developed a theory of atomic structure, confirmed by the experiments of Henry Moseley. In 1913, Peter Debye extended Bohr's theory by introducing elliptical orbits, a concept also introduced by Arnold Sommerfeld. This phase is known as old quantum theory.  According to Planck, each energy element ("E")" "is proportional to its frequency ("ν"):  where "h" is Planck's constant.  Planck cautiously insisted that this was only an aspect of the processes of absorption and emission of

Mathematical formulations.

In the mathematically rigorous formulation of quantum mechanics developed by Paul Dirac, David Hilbert, John von Neumann, and Hermann Weyl, the possible states of a quantum mechanical system are symbolized as unit vectors (called "state vectors"). Formally, these vectors are elements of a complex separable Hilbert space – variously called the "state space" or the "associated Hilbert space" of the system – that is well defined up to a complex number of norm 1 (the phase factor). In other words, the possible states are points in the projective space of a Hilbert space, usually called the complex projective space. The exact nature of this Hilbert space is dependent on the system – for example, the state space for position and momentum states is the space of square-integrable functions, while the state space for the spin of a single proton is just the product of two complex planes. Each observable is represented by a maximally Hermitian (precisely: by a self-adjoint) linear operator acting on the state space. Each eigenstate of an observable corresponds to an eigenvector of the operator, and the associated eigenvalue corresponds to the value of the observable in that eigenstate. If the operator's spectrum is discrete, the observable can attain only those discrete eigenvalues.  In the formalism of quantum mechanics, the state of a system at a given time is described by a complex wave function, also referred to as state vector in a complex vector space. This abstract mathematical object allows for the calculation of probabilities of outcomes of concrete experiments. For example, it allows one to compute the probability of finding an electron in a particular region around the nucleus at a particular time. Contrary to classical mechanics, one can never make simultaneous predictions of conjugate variables, such as position and momentum, to arbitrary precision. For instance, electrons may be considered (to a certain probability) to be located somewhere within a given region of space, but with their exact positions unknown. Contours of constant probability density, often referred to as "clouds", may be drawn around the nucleus of an atom to conceptualize where the electron might be located with the most probability. Heisenberg's uncertainty principle quantifies the inability to precisely locate the particle given its conjugate momentum.  According to one interpretation, as the result of a measurement, the wave function containing the probability information for a system collapses from a given initial state to a particular eigenstate. The possible results of a measurement are the eigenvalues of the operator representing the observable – which explains the choice of "Hermitian" operators, for which all the eigenvalues are real. The probability distribution of an observable in a given state can be found by computing the spectral decomposition of the corresponding operator. Heisenberg's uncertainty principle is represented by the statement that the operators corresponding to certain observables do not commute.  The probabilistic nature of quantum mechanics thus stems from the act of measurement. This is one of the most difficult aspects of quantum systems to understand. It was the central topic in the famous Bohr–Einstein debates, in which the two scientists attempted to clarify these fundamental principles by way of thought experiments. In the decades after the formulation of quantum mechanics, the question of what constitutes a "measurement" has been extensively studied. Newer interpretations of quantum mechanics have been formulated that do away with the concept of "wave function collapse" (see, for example, the relative state interpretation). The basic idea is that when a quantum system interacts with a measuring apparatus, their respective wave functions become entangled, so that the original quantum system ceases to exist as an independent entity. For details, see the article on measurement in quantum mechanics.  Generally, quantum mechanics does not assign definite values. Instead, it makes a prediction using a probability distribution; that is, it describes the probability of obtaining the possible outcomes from measuring an observable. Often these results are skewed by many causes, such as dense probability clouds. Probability clouds are approximate (but better than the Bohr model) whereby electron location is given by a probability function, the wave function eigenvalue, such that the probability is the squared modulus of the complex amplitude, or quantum state nuclear attraction. Naturally, these probabilities will depend on the quantum state at the "instant" of the measurement. Hence, uncertainty is involved in the value. There are, however, certain states that are associated with a definite value of a particular observable. These are known as eigenstates of the observable ("eigen" can be translated from German as meaning "inherent" or "characteristic").  In the everyday world, it is natural and intuitive to think of everything (every observable) as being in an eigenstate. Everything appears to have a definite position, a definite momentum, a definite energy, and a definite time of occurrence. However, quantum mechanics does not pinpoint the exact values of a particle's position and momentum (since they are conjugate pairs) or its energy and time (since they too are conjugate pairs). Rather, it provides only a range of probabilities in which that particle might be given its momentum and momentum probability. Therefore, it is helpful to use different words to describe states having "uncertain" values and states having "definite" values (eigenstates).  Usually, a system will not be in an eigenstate of the observable (particle) we are interested in. However, if one measures the observable, the wave function will instantaneously be an eigenstate (or "generalized" eigenstate) of that observable. This process is known as wave function collapse, a controversial and much-debated process that involves expanding the system under study to include the measurement device. If one knows the corresponding wave function at the instant before the measurement, one will be able to compute the probability of the wave function collapsing into each of the possible eigenstates.  For example, the free particle in the previous example will usually have a wave function that is a wave packet centered around some mean position "x" (neither an eigenstate of position nor of momentum). When one measures the position of the particle, it is impossible to predict with certainty the result. It is probable, but not certain, that it will be near "x", where the amplitude of the wave function is large. After the measurement is performed, having obtained some result "x", the wave function collapses into a position eigenstate centered at "x".  The time evolution of a quantum state is described by the Schrödinger equation, in which the Hamiltonian (the operator corresponding to the total energy of the system) generates the time evolution. The time evolution of wave functions is deterministic in the sense that – given a wave function at an "initial" time – it makes a definite prediction of what the wave function will be at any "later" time.  During a measurement, on the other hand, the change of the initial wave function into another, later wave function is not deterministic, it is unpredictable (i.e., random). A time-evolution simulation can be seen here.  Wave functions change as time progresses. The Schrödinger equation describes how wave functions change in time, playing a role similar to Newton's second law in classical mechanics. The Schrödinger equation, applied to the aforementioned example of the free particle, predicts that the center of a wave packet will move through space at a constant velocity (like a classical particle with no forces acting on it). However, the wave packet will also spread out as time progresses, which means that the position becomes more uncertain with time. This also has the effect of turning a position eigenstate (which can be thought of as an infinitely sharp wave packet) into a broadened wave packet that no longer represents a (definite, certain) position eigenstate.  Some wave functions produce probability distributions that are constant, or independent of time – such as when in a stationary state of definite energy, time vanishes in the absolute square of the wave function (this is the basis for the energy-time uncertainty principle). Many systems that are treated dynamically in classical mechanics are described by such "static" wave functions. For example, a single electron in an unexcited atom is pictured classically as a particle moving in a circular trajectory around the atomic nucleus, whereas in quantum mechanics, it is described by a static, spherically symmetric wave function surrounding the nucleus () (however, only the lowest angular momentum states, labeled "s", are spherically symmetric.)  The Schrödinger equation acts on the "entire" probability amplitude, not merely its absolute value. Whereas the absolute value of the probability amplitude encodes information about probabilities, its phase encodes information about the interference between quantum states. This gives rise to the "wave-like" behavior of quantum states.  Analytic solutions of the Schrödinger equation are known for very few relatively simple model Hamiltonians including the quantum harmonic oscillator, the particle in a box, the dihydrogen cation, and the hydrogen atom. Even the helium atom – which contains just two electrons – has defied all attempts at a fully analytic treatment.  However, there are techniques for finding approximate solutions. One method, called perturbation theory, uses the analytic result for a simple quantum mechanical model to create a result for a related but more complicated model by (for example) the addition of a weak potential energy. Another method is called "semi-classical equation of motion", which applies to systems for which quantum mechanics produces only small deviations from classical behavior. These deviations can then be computed based on the classical motion. This approach is particularly important in the field of quantum chaos.

Relation to other scientific theories.

The rules of quantum mechanics are fundamental. They assert that the state space of a system is a Hilbert space (crucially, that the space has an inner product) and that observables of the system are Hermitian operators acting on vectors in that space – although they do not tell us which Hilbert space or which operators. These can be chosen appropriately in order to obtain a quantitative description of a quantum system. An important guide for making these choices is the correspondence principle, which states that the predictions of quantum mechanics reduce to those of classical mechanics when a system moves to higher energies or, equivalently, larger quantum numbers, i.e. whereas a single particle exhibits a degree of randomness, in systems incorporating millions of particles averaging takes over and, at the high energy limit, the statistical probability of random behaviour approaches zero. In other words, classical mechanics is simply a quantum mechanics of large systems. This "high energy" limit is known as the "classical" or "correspondence limit". One can even start from an established classical model of a particular system, then try to guess the underlying quantum model that would give rise to the classical model in the correspondence limit. When quantum mechanics was originally formulated, it was applied to models whose correspondence limit was non-relativistic classical mechanics. For instance, the well-known model of the quantum harmonic oscillator uses an explicitly non-relativistic expression for the kinetic energy of the oscillator, and is thus a quantum version of the classical harmonic oscillator.  Early attempts to merge quantum mechanics with special relativity involved the replacement of the Schrödinger equation with a covariant equation such as the Klein–Gordon equation or the Dirac equation. While these theories were successful in explaining many experimental results, they had certain unsatisfactory qualities stemming from their neglect of the relativistic creation and annihilation of particles. A fully relativistic quantum theory required the development of quantum field theory, which applies quantization to a field (rather than a fixed set of particles). The first complete quantum field theory, quantum electrodynamics, provides a fully quantum description of the electromagnetic interaction. The full apparatus of quantum field theory is often unnecessary for describing electrodynamic systems. A simpler approach, one that has been used since the inception of quantum mechanics, is to treat charged particles as quantum mechanical objects being acted on by a classical electromagnetic field. For example, the elementary quantum model of the hydrogen atom describes the electric field of the hydrogen atom using a classical formula_2 Coulomb potential. This "semi-classical" approach fails if quantum fluctuations in the electromagnetic field play an important role, such as in the emission of photons by charged particles.  Quantum field theories for the strong nuclear force and the weak nuclear force have also been developed. The quantum field theory of the strong nuclear force is called quantum chromodynamics, and describes the interactions of subnuclear particles such as quarks and gluons. The weak nuclear force and the electromagnetic force were unified, in their quantized forms, into a single quantum field theory (known as electroweak theory), by the physicists Abdus Salam, Sheldon Glashow and Steven Weinberg. These three men shared the Nobel Prize in Physics in 1979 for this work.  It has proven difficult to construct quantum models of gravity, the remaining fundamental force. Semi-classical approximations are workable, and have led to predictions such as Hawking radiation. However, the formulation of a complete theory of quantum gravity is hindered by apparent incompatibilities between general relativity (the most accurate theory of gravity currently known) and some of the fundamental assumptions of quantum theory. The resolution of these incompatibilities is an area of active research. Candidates for a future theory of quantum gravity include string theory.  Classical mechanics has also been extended into the complex domain, with complex classical mechanics exhibiting behaviors similar to quantum mechanics.

Philosophical implications.

Since its inception, the many counter-intuitive aspects and results of quantum mechanics have provoked strong philosophical debates and many interpretations. Even fundamental issues, such as Max Born's basic rules about probability amplitudes and probability distributions, took decades to be appreciated by society and many leading scientists. Richard Feynman once said, "I think I can safely say that nobody understands quantum mechanics." According to Steven Weinberg, "There is now in my opinion no entirely satisfactory interpretation of quantum mechanics."  The Copenhagen interpretation – due largely to Niels Bohr and Werner Heisenberg – remains most widely accepted some 75 years after its enunciation. According to this interpretation, the probabilistic nature of quantum mechanics is not a "temporary" feature which will eventually be replaced by a deterministic theory, but is instead a "final" renunciation of the classical idea of "causality". It also states that any well-defined application of the quantum mechanical formalism must always make reference to the experimental arrangement, due to the conjugate nature of evidence obtained under different experimental situations.  Albert Einstein, himself one of the founders of quantum theory, did not accept some of the more philosophical or metaphysical interpretations of quantum mechanics, such as rejection of determinism and of causality. He famously said about this, "God does not play with dice". He rejected the concept that the state of a physical system depends on the experimental arrangement for its measurement. He held that a state of nature occurs in its own right, regardless of whether or how it might be observed. That view is supported by the currently accepted definition of a quantum state, which does not depend on the configuration space for its representation, that is to say, manner of observation. Einstein also believed that underlying quantum mechanics must be a theory that thoroughly and directly expresses the rule against action at a distance; in other words, he insisted on the principle of locality. He considered, but rejected on theoretical grounds, a particular proposal for hidden variables to obviate the indeterminism or acausality of quantum mechanical measurement. He believed that quantum mechanics was a currently valid but not a permanently definitive theory

Applications.

Quantum mechanics has had enormous success in explaining many of the features of our universe. Quantum mechanics is often the only theory that can reveal the individual behaviors of the subatomic particles that make up all forms of matter (electrons, protons, neutrons, photons, and others). Quantum mechanics has strongly influenced string theories, candidates for a Theory of Everything (see reductionism).  Quantum mechanics is also critically important for understanding how individual atoms are joined by covalent bonds to form molecules. The application of quantum mechanics to chemistry is known as quantum chemistry. Quantum mechanics can also provide quantitative insight into ionic and covalent bonding processes by explicitly showing which molecules are energetically favorable to which others and the magnitudes of the energies involved. Furthermore, most of the calculations performed in modern computational chemistry rely on quantum mechanics.  In many aspects modern technology operates at a scale where quantum effects are significant. Important applications of quantum theory include quantum chemistry, quantum optics, quantum computing, superconducting magnets, light-emitting diodes, the optical amplifier and the laser, the transistor and semiconductors such as the microprocessor, medical and research imaging such as magnetic resonance imaging and electron microscopy. Explanations for many biological and physical phenomena are rooted in the nature of the chemical bond, most notably the macro-molecule DNA.

Electronics.

Many modern electronic devices are designed using quantum mechanics. Examples include the laser, the transistor (and thus the microchip), the electron microscope, and magnetic resonance imaging (MRI). The study of semiconductors led to the invention of the diode and the transistor, which are indispensable parts of modern electronics systems, computer and telecommunication devices. Another application is for making laser diode and light emitting diode which are a high-efficiency source of light.  Many electronic devices operate under effect of quantum

Cryptography.

Researchers are currently seeking robust methods of directly manipulating quantum states. Efforts are being made to more fully develop quantum cryptography, which will theoretically allow guaranteed secure transmission of information.  An inherent advantage yielded by quantum cryptography when compared to classical cryptography is the detection of

Quantum computing.

Another goal is the development of quantum computers, which are expected to perform certain computational tasks exponentially faster than classical computers. Instead of using classical bits, quantum computers use qubits, which can be in superpositions of states. Quantum programmers are able to manipulate

Macroscale quantum effects.

While quantum mechanics primarily applies to the smaller atomic regimes of matter and energy, some systems exhibit quantum mechanical effects on a large scale. Superfluidity, the frictionless flow of a liquid at temperatures near absolute zero, is one well-known example. So is

Other phenomena.

Quantum theory also provides accurate descriptions for many previously unexplained phenomena, such as black-body radiation and the stability of the orbitals of electrons in atoms. It has also given insight into the workings of many different biological systems, including smell receptors and protein structures. Recent work on photosynthesis has provided evidence that

Examples.

Free particle.

For example, consider a free particle. In quantum mechanics, a free matter is described by a wave function. The particle properties of the matter become apparent when we measure its position and velocity. The wave properties of the matter become apparent when we measure its wave properties like interference. The wave–particle duality feature is incorporated in the relations of coordinates and operators in the formulation of quantum mechanics. Since the matter is free (not subject to any interactions), its quantum state can be represented as a wave of arbitrary shape and extending over space as a wave function. The position and momentum of the particle are observables. The Uncertainty Principle

Particle in a box.

The particle in a one-dimensional potential energy box is the most mathematically simple example where restraints lead to the quantization of energy levels. The box is defined as having zero potential energy everywhere "inside" a certain region, and therefore infinite potential energy everywhere "outside" that region. For the one-dimensional case in the formula_3 direction, the time-independent Schrödinger equation may be written  With the differential operator defined by  the previous equation is evocative of the classic kinetic energy analogue,  with state formula_7 in this case having energy formula_8 coincident with the kinetic energy of the particle.  The general solutions of the Schrödinger equation for the particle in a box are  or, from Euler's formula,  The infinite potential walls of the box determine the values of formula_11 and formula_12

Finite potential well.

A finite potential well is the generalization of the infinite potential well problem to potential wells having finite depth.  The finite potential well problem is mathematically more

Rectangular potential barrier.

This is a model for the quantum tunneling effect which plays an important role in

Harmonic oscillator.

As in the classical case, the potential for the quantum harmonic oscillator is given by  This problem can either be treated by directly solving the Schrödinger equation, which is not

Step potential.

The potential in this case is given by:  The solutions are superpositions of left- and right-moving waves: and with coefficients A and B determined from the boundary conditions and by imposing a continuous derivative on the solution,

References.

The following titles, all by working physicists, attempt to

Further reading.

On Wikibooks

Quantum mechanics (QM; also known as quantum physics, quantum theory, the wave mechanical model and matrix mechanics), part of quantum field theory, is a fundamental theory in physics. It describes physical properties of nature on an atomic scale.

La mécanique quantique est la branche de la physique théorique qui étudie et décrit les phénomènes fondamentaux à l'œuvre dans les systèmes physiques, plus particulièrement à l'échelle atomique et subatomique.


Plot.

A dark-haired woman is the sole survivor of a car crash on Mulholland Drive, a winding road high in the Hollywood Hills. Injured and in shock, she makes her way down into Los Angeles and sneaks into an apartment. Later that morning, an aspiring actress named Betty Elms arrives at the apartment, which is normally occupied by her Aunt Ruth. Betty is startled to find the woman, who has amnesia and calls herself "Rita" after seeing a poster for the film "Gilda" starring Rita Hayworth. To help the woman remember her identity, Betty looks in Rita's purse, where she finds a large amount of money and an unusual blue key.  At a diner called Winkie's, a man tells his companion about a nightmare in which he dreamt about encountering a horrible figure behind the diner. When they investigate, the figure appears, causing the man with the nightmare to collapse in fright. Elsewhere, director Adam Kesher has his film commandeered by mobsters, who insist he cast an unknown actress named Camilla Rhodes as the lead in his film. Adam resists, but after being thrown out of his house when he finds his wife cheating on him, he learns that his bank has closed his line of credit and he is broke. He agrees to meet a mysterious figure called The Cowboy, who urges him to cast Camilla Rhodes for his own good. Meanwhile, a bungling hit man attempts to steal a book full of phone numbers and leaves three people dead.  While trying to learn more about Rita's accident, Betty and Rita go to Winkie's and are served by a waitress named Diane, which causes Rita to remember the name "Diane Selwyn." They find Diane Selwyn in the phone book

Production.

Development.

Originally conceived as a television series, "Mulholland Drive" began as a 90-minute pilot produced for Touchstone Television and intended for the ABC television network. Tony Krantz, the agent who was responsible for the development of Twin Peaks, was "fired up" about doing another television show. Ironically, Lynch wrote "I will never do television again" on a piece of plywood. It was originally a script for a pilot for ABC. David Lynch sold the idea to ABC executives based only on the story of Rita emerging from the car accident with her purse containing $125,000 in cash and the blue key, and Betty trying to help her figure out who she is. An ABC executive recalled, "I remember the creepiness of this woman in this horrible, horrible crash, and David teasing us with the notion that people are chasing her. She's not just 'in' trouble—she "is" trouble. Obviously, we

Casting.

Lynch cast Naomi Watts and Laura Harring by their photographs. He called them in separately for half-hour interviews and told them that he had not seen any of their previous works in film or television. Harring considered it fateful that she was involved in a minor car accident on the way to the first interview, only to learn her character would also be involved in a car accident in the film. Watts arrived wearing jeans

Filming.

Filming for the television pilot began on location in Los Angeles in February 1999 and took six weeks. Ultimately, the network was unhappy with the pilot and decided not to place it on its schedule. Objections included the nonlinear storyline, the ages of Harring and Watts (whom they considered too old), cigarette smoking by Ann Miller's character and a close-frame shot of dog feces in one scene. Lynch remembered, "All I know is, I loved making it, ABC hated it, and I don't like the cut I turned in. I agreed with ABC that the longer cut was too slow, but I was forced to butcher it because we had a deadline, and there wasn't time to finesse anything. It lost texture, big scenes and storylines, and there are 300 tape copies of the bad version circulating around. Lots of people have seen it, which is embarrassing, because they're bad-quality tapes, too. I don't want to think about it."  The script was later rewritten and expanded when Lynch decided to transform it into a feature film. Describing the transition

Themes and interpretations.

Giving the film only the tagline "A love story in the city of dreams", David Lynch has refused to comment on "Mulholland Drive"s meaning or symbolism, leading to much discussion and multiple interpretations. "The Christian Science Monitor" film critic David Sterritt spoke with Lynch after the film screened at Cannes and wrote that the director "insisted that "Mulholland Drive" does tell a coherent, comprehensible story", unlike some of Lynch's earlier films like "Lost Highway". On the other hand, Justin Theroux said of Lynch's feelings on the multiple meanings people perceive in the film, "I think he's genuinely happy for it to mean anything you want. He loves it when people come up with really bizarre interpretations. David works from his subconscious."

Dreams and alternative realities.

An early interpretation of the film uses dream analysis to argue that the first part is a dream of the real Diane Selwyn, who has cast her dream-self as the innocent and hopeful "Betty Elms", reconstructing her history and persona into something like an old Hollywood film. In the dream, Betty is successful, charming, and lives the fantasy life of a soon-to-be-famous actress. The last one-fifth of the film presents Diane's real life, in which she has failed both personally and professionally. She arranges for Camilla, an ex-lover, to be killed, and unable to cope with the guilt, re-imagines her as the dependent, pliable amnesiac Rita. Clues to her inevitable demise, however, continue to appear throughout her dream.  This interpretation was similar to what Naomi Watts construed, when she said in an interview, "I thought Diane was the real character and that Betty was the person she wanted to be and had dreamed up. Rita is the damsel in distress

A "poisonous valentine to Hollywood".

Despite the proliferation of theories, critics note that no explanation satisfies all of the loose ends and questions that arise from the film. Stephen Holden of "The New York Times" writes, ""Mulholland Drive" has little to do with any single character's love life or professional ambition. The movie is an ever-deepening reflection on the allure of Hollywood and on the multiple role-playing and self-invention that the movie-going experience promises... What greater power is there than the power to enter and to program the dream life of the culture?" J. Hoberman from "The Village Voice" echoes

Queer identities.

The relationships between Betty and Rita, and Diane and Camilla have been variously described as "touching", "moving", as well as "titillating". Film critic Glenn Kenny, in a review of the film for "Premiere", said that the relationship between Betty and Rita is "possibly the healthiest, most positive amorous relationship ever depicted in a Lynch movie", whereas the French critic Thierry Jousse, in his review for "Cahiers du cinéma", said that the love between the women depicted is "of lyricism practically without equal in contemporary cinema". In the pages of "Film Comment", Philip Lopate states that the pivotal romantic interlude between Betty and Rita was made poignant and tender by Betty's "understanding for the first time, with self-surprise, that all her helpfulness and curiosity about the other woman had a point: desire... It is a beautiful moment, made all the more miraculous by its earned tenderness, and its distances from anything lurid." Stephanie Zacharek of "Salon" magazine stated that the scene's "eroticism [was] so potent it blankets the whole movie, coloring every scene that came before and every one that follows". Betty and Rita were chosen by the Independent Film Channel as the emblematic romantic couple of the 2000s. Writer Charles Taylor said, "Betty and

Characters.

Betty Elms (Naomi Watts) is the bright and talented newcomer to Los Angeles, described as "wholesome, optimistic, determined to take the town by storm", and "absurdly naïve". Her perkiness and intrepid approach to helping Rita because it is the right thing to do is reminiscent of Nancy Drew for reviewers. Her entire persona at first is an apparent cliché of small-town naïveté. But it is Betty's identity, or loss of it, that appears to be the focus of the film. For one critic, Betty performed the role of the film's consciousness and unconscious. Naomi Watts, who modeled Betty on Doris Day, Tippi Hedren and Kim Novak, observed that Betty is a thrill-seeker, someone "who finds herself in a world she doesn't belong in and is ready to take on a new identity, even if it's somebody else's". This has also led one theorist to conclude that since Betty had naïvely, yet eagerly entered the Hollywood system, she had become a "complicit actor" who had "embraced the very structure that" destroyed her. In an explanation of her development of the Betty character, Watts stated:  I had to therefore come up with my own decisions about what this meant and what this character was going through, what was dream and what was reality. My interpretation could end up being completely different, from both David and the audience. But I "did" have to reconcile all of that, and people seem to think it works.  Betty, however difficult to believe as her character is established, shows an astonishing depth of dimension in her audition. Previously rehearsed with Rita in the apartment, where Rita feeds her lines woodenly, the scene is "dreck" and "hollow; every line unworthy of a genuine actress's commitment", and Betty plays it in rehearsal as poorly as it is written. Nervous but plucky as ever at the audition, Betty enters the cramped room, but when pitted inches from her audition partner (Chad Everett), she turns it into a scene of powerful sexual tension that she fully controls and draws in every person in the room. The sexuality erodes immediately as the scene ends and she stands before them shyly waiting for their approval. One film analyst asserts that Betty's previously unknown ability steals the show, specifically, taking the dark mystery away from Rita and assigning it to herself, and by Lynch's use of this scene illustrates his use of deception in his characters. Betty's acting ability prompts Ruth Perlmutter to speculate if Betty is acting the role of Diane in either a dream or a parody of a film that ultimately turns against her.  Rita (Laura Elena Harring) is the mysterious and helpless apparent victim, a classic femme fatale with her dark, strikingly beautiful appearance. Roger Ebert was so impressed with Harring that he said of her "all she has to do is stand there and she is the first good argument in 55 years for a "Gilda" remake". She serves as the object of desire, directly oppositional to Betty's bright self-assuredness. She is also the first character with whom the audience identifies, and as viewers know her only as confused and frightened, not knowing who she is and where she is going, she represents their desire to make sense of the film through her identity. Instead of threatening, she inspires Betty to nurture, console and help her. Her amnesia makes her a blank persona, which one reviewer notes is "the vacancy that comes with extraordinary beauty and the onlooker's willingness to project any combination of angelic and devilish onto her". A character analysis of Rita asserts that her actions are the most genuine of the first portion of the film, since she has no memory and nothing to use as a frame of reference for how to behave. Todd McGowan, however, author of a book on themes in Lynch's films, states that the first portion of "Mulholland Drive" can be construed as Rita's fantasy, until Diane Selwyn is revealed; Betty is the object that overcomes Rita's anxiety about her loss of identity. According to film historian Steven Dillon, Diane transitions

Style.

The filmmaking style of David Lynch has been written about extensively using descriptions like "ultraweird", "dark" and "oddball". Todd McGowan writes, "One cannot watch a Lynch film the way one watches a standard Hollywood film noir nor in the way that one watches most radical films." Through Lynch's juxtaposition of cliché and surreal, nightmares and fantasies, nonlinear story lines, camera work, sound and lighting, he presents a film that challenges viewers to suspend belief of what they are experiencing. Many of the characters in "Mulholland Drive" are archetypes that can only be perceived as cliché: the new Hollywood hopeful, the femme fatale, the maverick director and shady powerbrokers that Lynch never seems to explore fully. Lynch places these often hackneyed characters in dire situations, creating dream-like qualities. By using these characters in scenarios that have components and references to dreams, fantasies and nightmares, viewers are left to decide, between the extremes, what is reality. One film analyst, Jennifer Hudson, writes of him, "Like most surrealists, Lynch's language of the unexplained is the fluid language of dreams."  David Lynch uses various methods of deception in "Mulholland Drive". A shadowy figure named Mr. Roque, who seems to control film studios, is portrayed by dwarf actor Michael J. Anderson (also from "Twin Peaks"). Anderson, who has only two lines and is seated in an enormous wooden wheelchair, was fitted with oversized foam prosthetic arms and legs in order to portray his head as abnormally small. During Adam and Camilla's party, Diane watches Camilla (played by Harring) with Adam on one arm, lean over and deeply kiss the same woman who appeared as Camilla (Melissa George) before the blue box was opened. Both then turn and smile pointedly at Diane. Film critic Franklin Ridgway writes that the depiction of such a deliberate "cruel and manipulative" act makes it unclear if Camilla is as capricious as she seems, or if Diane's paranoia is allowing the audience only to see what she senses. In a scene immediately after Betty's audition, the film cuts to a woman singing without apparent accompaniment, but as the camera pulls backwards, the audience sees that it is a recording studio. In actuality, it is a sound stage where Betty has just arrived to meet Adam Kesher, that the audience realizes as the camera pulls back further. Ridgway insists that such deception through artful camera work sets the viewer full of doubt about what is being presented: "It is as if the camera, in its graceful fluidity of motion, reassures us that it (thinks it) sees everything, has everything under control, even if we (and Betty) do not."  According to Stephen Dillon, Lynch's use of different camera positions throughout the film, such as hand-held points of view, makes the viewer "identify with the suspense of

Soundtrack.

The soundtrack of "Mulholland Drive" was supervised by Angelo Badalamenti, who collaborated on previous Lynch projects "Blue Velvet" and "Twin Peaks". Badalamenti, who was nominated for awards from the American Film Institute (AFI) and the British Academy of Film and Television Arts (BAFTA) for his work on the film, also has a cameo as an espresso aficionado and mobster.  Reviewers note that Badalamenti's ominous score, described as his "darkest yet", contributes to the sense of mystery as the film opens on the dark-haired woman's limousine, that contrasts with the bright, hopeful tones of Betty's first arrival in Los Angeles, with the score "acting as an emotional guide for the viewer". Film music journalist Daniel Schweiger remarks that Badalamenti's contribution to the score alternates from the "nearly motionless string dread to noir jazz and audio feedback", with "the rhythms building to an explosion of infinite darkness." Badalamenti described a particular technique of sound design applied to the film, by which he would provide Lynch with multiple ten- to twelve-minute tracks at slow tempo, that they called "firewood", from which Lynch "would take fragments and experiment with them resulting in a lot of film's eerie soundscapes."  Lynch uses two pop songs from the 1960s directly after one another, playing as two actresses are auditioning by lip synching them. According to an analyst of music used in Lynch films, Lynch's female characters are often unable to communicate through normal channels and are reduced to lip-synching or being otherwise stifled. Connie Stevens' "Sixteen Reasons" is the song being sung while the camera pans backwards to reveal several illusions, and Linda Scott's version of

Release.

"Mulholland Drive" premiered at the 2001 Cannes Film Festival in May to major critical acclaim. Lynch was awarded the Best Director prize at the festival, sharing it with co-winner Joel Coen for "The Man Who Wasn't There". It drew positive reviews from many critics and some of the strongest audience reactions of Lynch's career.

Box office.

Universal Pictures released "Mulholland Drive" theatrically in 66 theaters in the United States on October 12, 2001, grossing $587,591 over its opening weekend. It eventually expanded to its

Reception and legacy.

Since its release, "Mulholland Drive" has received "both some of the harshest epithets and some of the most lavish praise in recent cinematic history". On review aggregator website Rotten Tomatoes, the film has an approval rating of 83% based on 179 reviews, with an average rating of 7.62/10. The website's critical consensus reads, "David Lynch's dreamlike and mysterious "Mulholland Drive" is a twisty neo-noir with an unconventional structure that features a mesmerizing performance from Naomi Watts as a woman on the dark fringes of Hollywood." On Metacritic, which assigns a normalized rating to reviews, the film has a weighted average score of 85 out of 100 based on 35 critics, indicating "universal acclaim".  Roger Ebert of the "Chicago Sun-Times", who had previously been dismissive of Lynch's work, awarded the film four stars and said, "David Lynch has been working toward "Mulholland Drive" all of his career, and now that he's arrived there I forgive him for "Wild at Heart" and even "Lost Highway"... the movie is a surrealist dreamscape in the form of a Hollywood film

Home media.

The film was released on VHS and DVD by Universal Studios Home Video on April 9, 2002, in the United States and Canada, with few special features. It was released without chapter stops, a feature that Lynch objects to on the grounds that it "demystifies" the film. In spite of Lynch's concerns, the DVD release included a cover insert that provided "David Lynch's 10 Clues to Unlocking This Thriller", although one DVD reviewer noted that the clues may be "big obnoxious red herrings". Nick Coccellato of Eccentric Cinema gave the film a rating of nine out of ten and the DVD release an eight out of ten, saying that the lack of special features "only adds to the mystery the film itself possesses, in abundance". Special features in later versions

Awards and honors.

Lynch was nominated for an Academy Award for Best Director for the film. From the Hollywood Foreign Press, the film received four Golden Globe nominations, including Best Picture (Drama), Best Director and Best Screenplay. It was named Best Picture by the New York Film Critics Circle at the 2001 New York Film Critics Circle Awards and Online Film Critics Society.

Mulholland Drive (stylized as Mulholland Dr.) is a 2001 surreal neo-noir mystery film written and directed by David Lynch and starring Naomi Watts, Laura Harring, Justin Theroux, Ann Miller, Mark Pellegrino and Robert Forster. It tells the story of an aspiring actress named Betty Elms (Watts), newly arrived in Los Angeles, who meets and befriends an amnesiac woman (Harring) recovering from a car accident. The story follows several other vignettes and characters, including a Hollywood film director (Theroux).

Le film, à l'origine destiné à être un pilote de série télévisée, est en grande partie tourné en 1999 : Lynch ayant alors la volonté de laisser la fin ouverte dans l'éventualité d'une série. Cependant, après le visionnage de la version, les responsables de l'audiovisuel le rejettent. Lynch se décide à doter le projet d'une fin le transformant ainsi en long métrage. Le résultat, hybride entre pilote et long métrage couplé au style si particulier de Lynch, a laissé le sens général des événements dépeints dans l’œuvre sujet à interprétation. Le public, les critiques et même l'équipe de tournage en sont réduits à spéculer sur le sens émanant du film après le refus du réalisateur de fournir une explication de ses intentions quant au récit. En effet, Lynch préfère définir son œuvre de la façon suivante : « "" ».