text:
Talk:Haiku

Article about Haiku
Not sure if it fits, but I found, from Look Japan], https://web.archive.org/web/20020322194307/http://www.lookjapan.com/LBsc/99JulCul.html WhisperToMe (talk) 04:47, 1 May 2019 (UTC)
 * a Greek comment about the indescribable experiencing some haiku generate:
 * http://archive.fo/KxQGH

What is the purpose of this article?
I'm here because over the decades I've been stunned and amazed by haiku, the depth in so few words, and I thought, I'd like to try making a few or something. After reading this; no longer. Here's why, a quote from above:

"This article is for ENGLISH readers, and for a general public at that, and editors should keep that in the forefronts of their minds when they write or edit. It is recommended Wikipedia policy to present a general summary of the article in the opening sentences. Too often, writers take this to mean that all the minutiae of the theme has to telegraphed there, and that any small concession to general usage must be avoided at all cost. As a result, the reader is discouraged from perusing what remains. "

Bingo! Technical articles like this are Wikipedia's worst problem; experts 1) think a list of truisms is an explanation, and 2) fearing making a technically untrue statement 3) use such abstract (and vague) language and 4) since the meaning is so obvious to them, don't understand they are also describing 100 other possible things. It seems they also 5) think being an expert somehow makes them a good teacher, and hence 6) don't spend the required VERY HARD WORK needed for good teaching AND communication. Any child can talk, it's easy, right?

Do the editors seriously think the general public comes here to see long strings of Japanese characters and a lesson in Japanese history? ...in the lede section!??? I saw the term "self gratification" above and had to chuckle. "Lack of empathy," or failure to "target the audience" are more polite, —but "self absorbed" is not out of the question. For example; everybody here seems to agree 1) "cutting" is a key concept and 2) is a poor/useless term/description, 3) yet the term remains, unexplained/untranslated. Here's a suggestion.  Forget using a single term, and do some hard work, aka good writing, give an explanation.  Examples or complexity might be needed.  But handle it.

Of the sample poems, (which I was looking forward to as the meat,) only Old Pond made sense to me. Why do other sample poems use unexplained proper Japanese nouns and reference (other?) meaningless Japanese folklore and cultural presumptions? Why do I need those and full, advanced understanding of extremely nuanced linguistic terms to grasp the general construction rules and structures, etc? That just looks uppity and insults poor ignorant undeserving me. Who is the target audience!!?? Again, what is the purpose of this article?  --2602:306:CFCE:1EE0:6C37:E6B3:5E64:776E (talk) 20:10, 18 November 2019 (UTC)Just Saying
 * See Purpose. And Be bold. = paul2520 (talk) 17:21, 19 November 2019 (UTC)

A haiku is often a three line poem that consists of a phrase and a fragment where two of the lines comprise the phrase and the other line is the fragment. The fragment is either in the first or third lines.

Haiku are written in 17 syllables or less - preferably less according to the many online reputable sites. Haiku in English work the best around 10 to 12 syllables, otherwise they can become too wordy and  this can cloud the image.

These days a haiku captures one or two moments by using clear and vivid images...roses evoke spring, fallen leaves relate to autumn, etc). The poets  go outdoors and observe their surroundings; they write down images  to capture a succinct scene. A reader should be able to read the haiku and "see" the images from the words. It's challenging. Basically a haiku is an unfinished poem - the readers interpret what it means by putting the images together.  — Preceding unsigned comment added by 97.84.250.85 (talk) 20:33, 8 November 2020 (UTC)

Wiki Education assignment: Foundations of Literary Study
— Assignment last updated by Marisamasanchan (talk) 17:52, 11 May 2023 (UTC)

Italicizing Japanese Words
The article is not consistent in italicizing Japanese words: sometimes they are italicized, sometimes they are not. What rule do we follow -- italicize or not? LaivineOrodrim (talk) 04:17, 12 April 2023 (UTC)
 * I think that the poetic terms are not italicized, because they are being used as English words that refer to Japanese poetic forms. The manual of style says to italicize foreign words. Rachel Helps (BYU) (talk) 22:15, 10 July 2024 (UTC)

Hello
Hello, I'm the Wikipedian-in-residence at Brigham Young University. I'll be trying to improve parts of this page over the next month or so. Please let me know if you have any suggestions or concerns. Rachel Helps (BYU) (talk) 22:15, 10 July 2024 (UTC)

title: Talk:Haiku


text:
Hindi

Modern Standard Hindi, (, Ādhunik Mānak Hindī) commonly referred to as Hindi, is the standardised variety of the Hindustani language written in Devanagari script. It is the official language of India alongside English and the lingua franca of North India. Hindi is considered a Sanskritised register of the Hindustani language, which itself is based primarily on the Khariboli dialect of Delhi and neighbouring areas. It is an official language in nine states and three union territories and an additional official language in three other states. Hindi is also one of the 22 scheduled languages of the Republic of India.

Hindi is also spoken, to a lesser extent, in other parts of India (usually in a simplified or pidginised variety such as Bazaar Hindustani or Haflong Hindi). Outside India, several other languages are recognised officially as "Hindi" but do not refer to the Standard Hindi language described here and instead descend from other nearby languages, such as Awadhi and Bhojpuri. Such languages include Fiji Hindi, which has an official status in Fiji, and Caribbean Hindustani, which is spoken in Suriname, Trinidad and Tobago, and Guyana. Apart from the script and formal vocabulary, standard Hindi is mutually intelligible with standard Urdu, another recognised register of Hindustani, as both Hindi and Urdu share a core vocabulary base derived from Prakrit (a descendant of Sanskrit).

Hindi is the fourth most-spoken first language in the world, after Mandarin, Spanish and English. If counted together with the mutually intelligible Urdu, it is the third most-spoken language in the world, after Mandarin and English. According to reports of Ethnologue (2022, 25th edition) Hindi is the third most-spoken language in the world including first and second language speakers.

Hindi is the fastest growing language of India, followed by Kashmiri in the second place, with Meitei (officially called Manipuri) as well as Gujarati, in the third place, and Bengali in the fourth place, according to the 2011 census of India.

Terminology
The term Hindī originally was used to refer to inhabitants of the Indo-Gangetic Plain. It was borrowed from Classical Persian هندی Hindī (Iranian Persian pronunciation: Hendi), meaning "of or belonging to Hind (India)" (hence, "Indian").

Another name Hindavī (हिन्दवी) or Hinduī (हिन्दुई) (from "of or belonging to the Hindu/Indian people") was often used in the past, for example by Amir Khusrau in his poetry.

The terms "Hindi" and "Hindu" trace back to Old Persian which derived these names from the Sanskrit name Sindhu (सिन्धु), referring to the Indus River. The Greek cognates of the same terms are "Indus" (for the river) and "India" (for the land of the river).

The term Modern Standard Hindi is commonly used to specifically refer the modern literary Hindi language, as opposed to colloquial and regional varieties that are also referred to as Hindi in a wider sense.

Middle Indo-Aryan to Hindi
Like other Indo-Aryan languages, Hindi is a direct descendant of an early form of Vedic Sanskrit, through Shauraseni Prakrit and Śauraseni Apabhraṃśa (from Sanskrit apabhraṃśa "corrupt"), which emerged in the 7th century CE.

The sound changes that characterised the transition from Middle Indo-Aryan to Hindi are:
 * Compensatory lengthening of vowels preceding geminate consonants, sometimes with spontaneous nasalisation: Skt. hasta "hand" > Pkt. hattha > hāth
 * Loss of all word-final vowels: rātri "night" > rattī > rāt
 * Formation of nasalised long vowels from nasal consonants (-VNC- > -V̄̃C-): bandha "bond" > bā̃dh
 * Loss of unaccented or unstressed short vowels (reflected in schwa deletion): susthira "firm" > sutthira > suthrā
 * Collapsing of adjacent vowels (including separated by a hiatus: apara "other" > avara > aur
 * Final -m to -ṽ: grāma "village" > gāma > gāṽ
 * Intervocalic -ḍ- to -ṛ- or -l-: taḍāga "pond" > talāv, naḍa "reed" > nal.
 * v > b: vivāha "marriage" > byāh

Hindustani
During the period of Delhi Sultanate, which covered most of today's north India, eastern Pakistan, southern Nepal and Bangladesh and which resulted in the contact of Hindu and Muslim cultures, the Sanskrit and Prakrit base of Old Hindi became enriched with loanwords from Persian, evolving into the present form of Hindustani. Hindi achieved prominence in India after it became the official language of the imperial court during the reign of Shah Jahan. It is recorded that Emperor Aurangzeb spoke in Hindvi. The Hindustani vernacular became an expression of Indian national unity during the Indian Independence movement, and continues to be spoken as the common language of the people of the northern Indian subcontinent, which is reflected in the Hindustani vocabulary of Bollywood films and songs.

Standard Hindi is based on the Delhi dialect, the vernacular of Delhi and the surrounding region, which came to replace earlier prestige languages such as Awadhi and Braj. It developed by extracting Persian and Arabic words from the Hindustani language and replacing with Sanskrit words,. Modern Hindi became a literary language in the 18th century. Earliest examples could be found as Prēm Sāgar by Lallu Lal, Batiyāl Pachīsī of Sadal Misra, and Rānī Kētakī Kī Kahānī of Insha Allah Khan which were published in Devanagari script during the early 19th century.

John Gilchrist was principally known for his study of the Hindustani language, which was adopted as the lingua franca of northern India (including what is now present-day Pakistan) by British colonists and indigenous people. He compiled and authored An English-Hindustani Dictionary, A Grammar of the Hindoostanee Language, The Oriental Linguist, and many more. His lexicon of Hindustani was published in the Perso-Arabic script, Nāgarī script, and in Roman transliteration.In the late 19th century, a movement to further develop Hindi as a standardised form of Hindustani separate from Urdu took form. In 1881, Bihar accepted Hindi as its sole official language, replacing Urdu, and thus became the first state of India to adopt Hindi. However, in 2014, Urdu was accorded second official language status in the state.

Independent India
After independence, the Government of India instituted the following conventions:
 * Standardisation of grammar: In 1954, the Government of India set up a committee to prepare a grammar of Hindi; The committee's report was released in 1958 as A Basic Grammar of Modern Hindi.
 * Standardisation of the orthography, using the Devanagari script, by the Central Hindi Directorate of the Ministry of Education and Culture to bring about uniformity in writing, to improve the shape of some Devanagari characters, and introducing diacritics to express sounds from other languages.

On 14 September 1949, the Constituent Assembly of India adopted Hindi written in the Devanagari script as the official language of the Republic of India replacing the previous usage of Hindustani in the Perso-Arabic script in the British Indian Empire. To this end, several stalwarts rallied and lobbied pan-India in favour of Hindi, most notably Beohar Rajendra Simha along with Hazari Prasad Dwivedi, Kaka Kalelkar, Maithili Sharan Gupt and Seth Govind Das who even debated in Parliament on this issue. As such, on the 50th birthday of Beohar Rajendra Simha on 14 September 1949, the efforts came to fruition following the adoption of Hindi as the official language. Now, it is celebrated as Hindi Day.

India
Part XVII of the Indian Constitution deals with the official language of the Indian Union. Under Article 343, the official languages of the Union have been prescribed, which includes Hindi in Devanagari script and English:

(1) The official language of the Union shall be Hindi in Devanagari script. The form of numerals to be used for the official purposes of the Union shall be the international form of Indian numerals.

(2) Notwithstanding anything in clause (1), for a period of fifteen years from the commencement of this Constitution, the English language shall continue to be used for all the official purposes of the Union for which it was being used immediately before such commencement: Provided that the President may, during the said period, by order authorise the use of the Hindi language in addition to the English language and of the Devanagari form of numerals in addition to the international form of Indian numerals for any of the official purposes of the Union.

Article 351 of the Indian constitution states:

"It shall be the duty of the Union to promote the spread of the Hindi language, to develop it so that it may serve as a medium of expression for all the elements of the composite culture of India and to secure its enrichment by assimilating without interfering with its genius, the forms, style and expressions used in Hindustani and in the other languages of India specified in the Eighth Schedule, and by drawing, wherever necessary or desirable, for its vocabulary, primarily on Sanskrit and secondarily on other languages."

It was envisioned that Hindi would become the sole working language of the Union Government by 1965 (per directives in Article 344 (2) and Article 351), with state governments being free to function in the language of their own choice. However, widespread resistance to the imposition of Hindi on non-native speakers, especially in South India (such as those in Tamil Nadu) led to the passage of the Official Languages Act of 1963, which provided for the continued use of English indefinitely for all official purposes, although the constitutional directive for the Union Government to encourage the spread of Hindi was retained and has strongly influenced its policies.

Article 344 (2b) stipulates that the official language commission shall be constituted every ten years to recommend steps for the progressive use of Hindi language and impose restrictions on the use of the English language by the union government. In practice, the official language commissions are constantly endeavouring to promote Hindi but not imposing restrictions on English in official use by the union government.

At the state level, Hindi is the official language of the following Indian states: Bihar, Chhattisgarh, Haryana, Himachal Pradesh, Jharkhand, Madhya Pradesh, Rajasthan, Uttar Pradesh and Uttarakhand. Hindi is an official language of Gujarat, along with Gujarati. It acts as an additional official language of West Bengal in blocks and sub-divisions with more than 10% of the population speaking Hindi. Similarly, Hindi is accorded the status of official language in the following Union Territories: Delhi, Andaman and Nicobar Islands and Dadra and Nagar Haveli and Daman and Diu.

Although there is no specification of a national language in the constitution, it is a widely held belief that Hindi is the national language of India. This is often a source of friction and contentious debate. In 2010, the Gujarat High Court clarified that Hindi is not the national language of India because the constitution does not mention it as such. In 2021, in a Narcotics Drugs and Psychotropic Substances (NDPS) Act case involving Gangam Sudhir Kumar Reddy, the Bombay High Court claimed Hindi is the national language while refusing Reddy bail, after he argued against his statutory rights being read in Hindi, despite being a native Telugu speaker. Reddy has filed a Special Leave Petition before the Supreme Court, challenging the Bombay High Court's observation, and contended that it failed to appreciate that Hindi is not the national language in India.

In 2018, The Supreme Court has stayed a judgment of Madhya Pradesh High Court that held that the Hindi version of enactment will prevail if there is a variation in its Hindi version and English version. The prominence thus attached to English over Hindi in the judgement underlines the social significance of English over Hindi.

Fiji
Outside Asia, the Awadhi language (an Eastern Hindi dialect) with influence from Bhojpuri, Bihari languages, Fijian and English is spoken in Fiji. It is an official language in Fiji as per the 1997 Constitution of Fiji, where it referred to it as "Hindustani"; however, in the 2013 Constitution of Fiji, it is simply called "Fiji Hindi" as the official language. It is spoken by 380,000 people in Fiji.

Nepal
Hindi is spoken as a first language by about 77,569 people in Nepal according to the 2011 Nepal census, and further by 1,225,950 people as a second language. A Hindi proponent, Indian-born Paramananda Jha, was elected vice-president of Nepal. He took his oath of office in Hindi in July 2008. This created protests in the streets for 5 days; students burnt his effigies, and there was a general strike in 22 districts. Nepal Supreme Court ruled in 2009 that his oath in Hindi was invalid and he was kept "inactive" as vice-president. An "angry" Jha said, "I cannot be compelled to take the oath now in Nepali. I might rather take it in English."

South Africa
Hindi is a protected language in South Africa. According to the Constitution of South Africa, the Pan South African Language Board must promote and ensure respect for Hindi along with other languages. According to a doctoral dissertation by Rajend Mesthrie in 1985, although Hindi and other Indian languages have existed in South Africa for the last 125 years, there are no academic studies of any of them – of their use in South Africa, their evolution and current decline.

United Arab Emirates
Hindi is adopted as the third official court language in the Emirate of Abu Dhabi. As a result of this status, the Indian workforce in UAE can file their complaints to the labour courts in the country in their own mother-tongue.

Geographical distribution
Hindi is the lingua franca of northern India (which contains the Hindi Belt), as well as an official language of the Government of India, along with English.

In Northeast India a pidgin known as Haflong Hindi has developed as a lingua franca for the people living in Haflong, Assam who speak other languages natively. In Arunachal Pradesh, Hindi emerged as a lingua franca among locals who speak over 50 dialects natively.

Hindi is quite easy to understand for many Pakistanis, who speak Urdu, which, like Hindi, is a standard register of the Hindustani language; additionally, Indian media are widely viewed in Pakistan.

A sizeable population in Afghanistan, especially in Kabul, can also speak and understand Hindi-Urdu due to the popularity and influence of Bollywood films, songs and actors in the region.

Hindi is also spoken by a large population of Madheshis (people having roots in north-India but having migrated to Nepal over hundreds of years) of Nepal. Apart from this, Hindi is spoken by the large Indian diaspora which hails from, or has its origin from the "Hindi Belt" of India. A substantially large North Indian diaspora lives in countries like the United States of America, the United Kingdom, the United Arab Emirates, Trinidad and Tobago, Guyana, Suriname, South Africa, Fiji and Mauritius, where it is natively spoken at home and among their own Hindustani-speaking communities. Outside India, Hindi speakers are 8 million in Nepal; 863,077 in the United States of America; 450,170 in Mauritius; 380,000 in Fiji; 250,292 in South Africa; 150,000 in Suriname; 100,000 in Uganda; 45,800 in the United Kingdom; 20,000 in New Zealand; 20,000 in Germany; 26,000 in Trinidad and Tobago; 3,000 in Singapore.

Comparison with Standard Urdu
Linguistically, Hindi and Urdu are two registers of the same language and are mutually intelligible. Both Hindi and Urdu share a core vocabulary of native Prakrit and Sanskrit-derived words. However, Hindi is written in the Devanagari script and contains more direct tatsama Sanskrit-derived words than Urdu, whereas Urdu is written in the Perso-Arabic script and uses more Arabic and Persian loanwords compared to Hindi. Because of this, as well as the fact that the two registers share an identical grammar,  a consensus of linguists consider them to be two standardised forms of the same language, Hindustani or Hindi-Urdu. Hindi is the most commonly used scheduled language in India and is one of the two official languages of the union, the other being English. Urdu is the national language and lingua franca of Pakistan and is one of 22 scheduled languages of India, also having official status in Uttar Pradesh, Jammu and Kashmir, Delhi, Telangana, Andhra Pradesh and Bihar.

Script
Hindi is written in the Devanagari script, an abugida. Devanagari consists of 11 vowels and 33 consonants and is written from left to right. Unlike Sanskrit, Devanagari is not entirely phonetic for Hindi, especially failing to mark schwa deletion in spoken Standard Hindi.

Romanisation
The Government of India uses Hunterian transliteration as its official system of writing Hindi in the Latin script. Various other systems also exist, such as IAST, ITRANS and ISO 15919.

Romanised Hindi, also called Hinglish, is the dominant form of Hindi online. In an analysis of YouTube comments, Palakodety et al., identified that 52% of comments were in Romanised Hindi, 46% in English, and 1% in Devanagari Hindi.

Vocabulary
Traditionally, Hindi words are divided into five principal categories according to their etymology:

 * Tatsam (तत्सम ) words: These are words which are spelled the same in Hindi as in Sanskrit (except for the absence of final case inflections). They include words inherited from Sanskrit via Prakrit which have survived without modification (e.g. Hindi नाम nām / Sanskrit नाम nāma, "name", as well as forms borrowed directly from Sanskrit in more modern times (e.g. प्रार्थना prārthanā, "prayer"). Pronunciation, however, conforms to Hindi norms and may differ from that of classical Sanskrit. Amongst nouns, the tatsam word could be the Sanskrit non-inflected word-stem, or it could be the nominative singular form in the Sanskrit nominal declension.
 * Ardhatatsam (अर्धतत्सम ) words: Such words are typically earlier loanwords from Sanskrit which have undergone sound changes subsequent to being borrowed. (e.g. Hindi सूरज sūraj from Sanskrit सूर्य sūrya)
 * Tadbhav (तद्भव ) words: These are native Hindi words derived from Sanskrit after undergoing phonological rules (e.g. Sanskrit कर्म karma, "deed" becomes Shauraseni Prakrit कम्म kamma, and eventually Hindi काम kām, "work") and are spelled differently from Sanskrit.
 * Deshaj (देशज ) words: These are words that were not borrowings but do not derive from attested Indo-Aryan words either. Belonging to this category are onomatopoetic words or ones borrowed from local non-Indo-Aryan languages.
 * Videshī (विदेशी ) words: These include all loanwords from non-indigenous languages. The most frequent source languages in this category are Persian, Arabic, English and Portuguese. Examples are क़िला qila "fort" from Persian, कमेटी kameṭī from English committee.

Hindi also makes extensive use of loan translation (calqueing) and occasionally phono-semantic matching of English.

Prakrit
Hindi has naturally inherited a large portion of its vocabulary from Shauraseni Prakrit, in the form of tadbhava words. This process usually involves compensatory lengthening of vowels preceding consonant clusters in Prakrit, e.g. Sanskrit tīkṣṇa > Prakrit tikkha > Hindi tīkhā.

Sanskrit
Much of Standard Hindi's vocabulary is borrowed from Sanskrit as tatsam borrowings, especially in technical and academic fields. The formal Hindi standard, from which much of the Persian, Arabic and English vocabulary has been replaced by neologisms compounding tatsam words, is called Śuddh Hindi (pure Hindi), and is viewed as a more prestigious dialect over other more colloquial forms of Hindi.

Excessive use of tatsam words sometimes creates problems for native speakers. They may have Sanskrit consonant clusters which do not exist in Hindustani, causing difficulties in pronunciation.

As a part of the process of Sanskritisation, new words are coined using Sanskrit components to be used as replacements for supposedly foreign vocabulary. Usually these neologisms are calques of English words already adopted into spoken Hindi. Some terms such as dūrbhāṣ "telephone", literally "far-speech" and dūrdarśan "television", literally "far-sight" have even gained some currency in formal Hindi in the place of the English borrowings (ṭeli)fon and ṭīvī.

Persian
Hindi also features significant Persian influence, standardised from spoken Hindustani. Early borrowings, beginning in the mid-12th century, were specific to Islam (e.g. Muhammad, Islām) and so Persian was simply an intermediary for Arabic. Later, under the Delhi Sultanate and Mughal Empire, Persian became the primary administrative language in the Hindi heartland. Persian borrowings reached a heyday in the 17th century, pervading all aspects of life. Even grammatical constructs, namely the izafat, were assimilated into Hindi.

The status of Persian language then and thus its influence, is also visible in Hindi proverbs:

The emergence of Modern Standard Hindi in the 19th century went along with the Sanskritisation of its vocabulary, leading to a marginalisation of Persian vocabulary in Hindi, which continued after Partition when the Indian government co-opted the policy of Sanskritisation. However, many Persian words (e.g. bas "enough", khud "self") have remained entrenched in Standard Hindi, and a larger amount are still used in Urdu poetry written in the Devanagari script. Many words borrowed from Persian in turn were loanwords from Arabic (e.g. muśkil "difficult", havā "air", x(a)yāl "thought", kitāb "book").

 * क़ानून ultimately comes from the Greek κανών (kanōn).
 * क़मीज़ ultimately comes from the Latin "camisia" pronunciation reinforced by Portuguese "camisa".

Portuguese
Many Hindustani words were derived from Portuguese due to interaction with colonists and missionaries:

Literature
Hindi literature is broadly divided into four prominent forms or styles, being Bhakti (devotional – Kabir, Raskhan); Śṛṇgār (beauty – Keshav, Bihari); Vīgāthā (epic); and Ādhunik (modern).

Medieval Hindi literature is marked by the influence of Bhakti movement and the composition of long, epic poems. It was primarily written in other varieties of Hindi, particularly Avadhi and Braj Bhasha, but to a degree also in Delhavi, the basis for Standard Hindi. During the British Raj, Hindustani became the prestige dialect.

Chandrakanta, written by Devaki Nandan Khatri in 1888, is considered the first authentic work of prose in modern Hindi. The person who brought realism in Hindi prose literature was Munshi Premchand, who is considered the most revered figure in the world of Hindi fiction and progressive movement. Literary, or Sāhityik, Hindi was popularised by the writings of Swami Dayananda Saraswati, Bhartendu Harishchandra and others. The rising numbers of newspapers and magazines made Hindustani popular with educated people.

The Dvivedī Yug ("Age of Dwivedi") in Hindi literature lasted from 1900 to 1918. It is named after Mahavir Prasad Dwivedi, who played a major role in establishing Standard Hindi in poetry and broadening the acceptable subjects of Hindi poetry from the traditional ones of religion and romantic love.

In the 20th century, Hindi literature saw a romantic upsurge. This is known as Chāyāvād (shadow-ism) and the literary figures belonging to this school are known as Chāyāvādī. Jaishankar Prasad, Suryakant Tripathi 'Nirala', Mahadevi Varma and Sumitranandan Pant, are the four major Chāyāvādī poets.

Uttar Ādhunik is the post-modernist period of Hindi literature, marked by a questioning of early trends that copied the West as well as the excessive ornamentation of the Chāyāvādī movement, and by a return to simple language and natural themes.

Internet
Hindi literature, music, and film have all been disseminated via the internet. In 2015, Google reported a 94% increase in Hindi-content consumption year-on-year, adding that 21% of users in India prefer content in Hindi. Many Hindi newspapers also offer digital editions.

Sample text
The following is a sample text in High Hindi, of Article 1 of the Universal Declaration of Human Rights (by the United Nations):
 * Hindi in Devanagari Script
 * अनुच्छेद १(एक): सभी मनुष्य जन्म से स्वतन्त्र तथा मर्यादा और अधिकारों में समान होते हैं। वे तर्क और विवेक से सम्पन्न हैं तथा उन्हें भ्रातृत्व की भावना से परस्पर के प्रति कार्य करना चाहिए।
 * अनुच्छेद १(एक): सभी मनुष्य जन्म से स्वतन्त्र तथा मर्यादा और अधिकारों में समान होते हैं। वे तर्क और विवेक से सम्पन्न हैं तथा उन्हें भ्रातृत्व की भावना से परस्पर के प्रति कार्य करना चाहिए।

 * Transliteration (ISO):

 * Transcription (IPA):

 * Gloss (word-to-word):
 * Article 1 (one) – All humans birth from independent and dignity and rights in equal are. They logic and conscience from endowed are and they fraternity in the spirit of each other towards work should.

 * Translation (grammatical):
 * Article 1 – All humans are born independent and equal in dignity and rights. They are endowed with logic and conscience and they should work towards each other in the spirit of fraternity.

Dictionaries

 * Academic Room Hindi Dictionary Mobile App developed in the Harvard Innovation Lab (iOS, Android and Blackberry)
 * Academic Room Hindi Dictionary Mobile App developed in the Harvard Innovation Lab (iOS, Android and Blackberry)
 * Academic Room Hindi Dictionary Mobile App developed in the Harvard Innovation Lab (iOS, Android and Blackberry)
 * Academic Room Hindi Dictionary Mobile App developed in the Harvard Innovation Lab (iOS, Android and Blackberry)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Hindi


text:
Huginn and Muninn

In Norse mythology, Huginn (Old Norse: "thought" ) and Muninn (Old Norse "memory" or "mind" ) are a pair of ravens that fly all over the world, Midgard, and bring information to the god Odin. Huginn and Muninn are attested in the Poetic Edda, compiled in the 13th century from earlier traditional sources: the Prose Edda and Heimskringla; in the Third Grammatical Treatise, compiled in the 13th century by Óláfr Þórðarson; and in the poetry of skalds. The names of the ravens are sometimes anglicized as Hugin and Munin, the same spelling as used in modern Danish, Norwegian, and Swedish.

In the Poetic Edda, a disguised Odin expresses that he fears the ravens may not return from their daily flights. The Prose Edda explains that Odin is referred to as Hrafnaguð (O.N.: ; "raven-god") due to his association with Huginn and Muninn. In the Prose Edda and the Third Grammatical Treatise, the two ravens are described as perching on Odin's shoulders. Heimskringla details that Odin gave Huginn and Muninn the ability to speak.

Examples of artifacts that may depict Odin with one of the ravens include Migration Period golden bracteates, Vendel era helmet plates, a pair of identical Germanic Iron Age bird-shaped brooches, Viking Age objects depicting a moustached man wearing a helmet, and a portion of the 10th or 11th century Thorwald's Cross. Huginn and Muninn's role as Odin's messengers has been linked to shamanic practices, the Norse raven banner, general raven symbolism among the Germanic peoples, and the Norse concepts of the fylgja and the hamingja.

"Huginn" and "Muninn" are the names for the missions of European Space Agency astronauts – respectively of Andreas Mogensen of Denmark, and Marcus Wandt of Sweden – which are set to coincide aboard the International Space Station in January 2024.

Attestations
In the Poetic Edda poem Grímnismál, the god Odin (disguised as Grímnir) provides the young Agnarr with information about Odin's companions. He tells the prince about Odin's wolves Geri and Freki, and, in the next stanza of the poem, states that Huginn and Muninn fly daily across the entire world, Midgard. Grímnir says that he worries Huginn may not come back, yet more does he fear for Muninn: In the Prose Edda book Gylfaginning (chapter 38), the enthroned figure of High tells Gangleri (king Gylfi in disguise) that two ravens named Huginn and Muninn sit on Odin's shoulders. The ravens tell Odin everything they see and hear. Odin sends Huginn and Muninn out at dawn, and the birds fly all over the world before returning at dinner-time. As a result, Odin is kept informed of many events. High adds that it is from this association that Odin is referred to as "raven-god". The above-mentioned stanza from Grímnismál is then quoted.

In the Prose Edda book Skáldskaparmál (chapter 60), Huginn and Muninn appear in a list of poetic names for ravens. In the same chapter, excerpts from a work by the skald Einarr Skúlason are provided. In these excerpts Muninn is referenced in a common noun for 'raven' and Huginn is referenced in a kenning for 'carrion'.

In the Heimskringla book Ynglinga saga, a euhemerized account of the life of Odin is provided. Chapter 7 describes that Odin had two ravens, and upon these ravens he bestowed the gift of speech. These ravens flew all over the land and brought him information, causing Odin to become "very wise in his lore."

In the Third Grammatical Treatise an anonymous verse is recorded that mentions the ravens flying from Odin's shoulders; Huginn seeking hanged men, and Muninn slain bodies. The verse reads:
 * Two ravens flew from Hnikar’s [Óðinn’s]
 * shoulders; Huginn to the hanged and
 * Muninn to the slain [lit. corpses].

Archaeological record
Migration Period (5th and 6th centuries CE) gold bracteates (types A, B, and C) feature a depiction of a human figure above a horse, holding a spear and flanked by one or more often two birds. The presence of the birds has led to the iconographic identification of the human figure as the god Odin, flanked by Huginn and Muninn. Like Snorri's Prose Edda description of the ravens, a bird is sometimes depicted at the ear of the human, or at the ear of the horse. Bracteates have been found in Denmark, Sweden, Norway and, in smaller numbers, England and areas south of Denmark. Austrian Germanist Rudolf Simek states that these bracteates may depict Odin and his ravens healing a horse and may indicate that the birds were originally not simply his battlefield companions but also "Odin's helpers in his veterinary function."

Vendel era helmet plates (from the 6th or 7th century) found in a grave in Sweden depict a helmeted figure holding a spear and a shield while riding a horse, flanked by two birds. The plate has been interpreted as Odin accompanied by two birds: his ravens.

A pair of identical Germanic Iron Age bird-shaped brooches from Bejsebakke in northern Denmark may be depictions of Huginn and Muninn. The back of each bird features a mask motif, and the feet of the birds are shaped like the heads of animals. The feathers of the birds are also composed of animal heads. Together, the animal heads on the feathers form a mask on the back of the bird. The birds have powerful beaks and fan-shaped tails, indicating that they are ravens. The brooches were intended to be worn on each shoulder, after Germanic Iron Age fashion. Archaeologist Peter Vang Petersen comments that while the symbolism of the brooches is open to debate, the shape of the beaks and tail feathers confirm that the brooch depictions are ravens. Petersen notes that "raven-shaped ornaments worn as a pair, after the fashion of the day, one on each shoulder, makes one's thoughts turn towards Odin's ravens and the cult of Odin in the Germanic Iron Age." Petersen says that Odin is associated with disguise and that the masks on the ravens may be portraits of Odin.

The Oseberg tapestry fragments, discovered within the Viking Age Oseberg ship burial in Norway, feature a scene containing two black birds hovering over a horse, possibly originally leading a wagon (as a part of a procession of horse-led wagons on the tapestry). In her examination of the tapestry, scholar Anne Stine Ingstad interprets these birds as Huginn and Muninn flying over a covered cart containing an image of Odin, drawing comparison with the images of Nerthus attested by Tacitus in 1 CE.

Excavations in Ribe in Denmark have recovered a Viking Age lead metal-caster's mould and 11 identical casting-moulds. These objects depict a moustached man wearing a helmet that features two head-ornaments. Archaeologist Stig Jensen proposes that these ornaments should be interpreted as Huginn and Muninn, and the wearer as Odin. He notes that "similar depictions occur everywhere the Vikings went—from eastern England to Russia and naturally also in the rest of Scandinavia."

A portion of Thorwald's Cross (a partly surviving runestone erected at Kirk Andreas on the Isle of Man) depicts a bearded human holding a spear downward at a wolf, his right foot in its mouth, and a large bird on his shoulder. Andy Orchard comments that this bird may be either Huginn or Muninn. Rundata dates the cross to 940, while Pluskowski dates it to the 11th century. This depiction has been interpreted as Odin, with a raven or eagle at his shoulder, being consumed by the monstrous wolf Fenrir during the events of Ragnarök.

In November 2009, the Roskilde Museum announced the discovery and subsequent display of a niello-inlaid silver figurine found in Lejre, Denmark, which they dubbed "Odin from Lejre". The silver object depicts a person sitting on a throne. The throne features the heads of animals and is flanked by two birds. The Roskilde Museum identifies the figure as Odin sitting on his throne Hliðskjálf, flanked by the ravens Huginn and Muninn.

Interpretations
Scholars have linked Odin's relation to Huginn and Muninn to shamanic practice. John Lindow relates Odin's ability to send his "thought" (Huginn) and "mind" (Muninn) to the trance-state journey of shamans. Lindow says the Grímnismál stanza where Odin worries about the return of Huginn and Muninn "would be consistent with the danger that the shaman faces on the trance-state journey."

Rudolf Simek is critical of the approach, stating that "attempts have been made to interpret Odin's ravens as a personification of the god's intellectual powers, but this can only be assumed from the names Huginn and Muninn themselves which were unlikely to have been invented much before the 9th or 10th centuries" yet that the two ravens, as Odin's companions, appear to derive from much earlier times. Instead, Simek connects Huginn and Muninn with wider raven symbolism in the Germanic world, including the raven banner (described in English chronicles and Scandinavian sagas), a banner which was woven in a method that allowed it, when fluttering in the wind, to appear as if the raven depicted upon it was beating its wings.

Anthony Winterbourne connects Huginn and Muninn to the Norse concepts of the fylgja—a concept with three characteristics; shape-shifting abilities, good fortune, and the guardian spirit—and the hamingja—the ghostly double of a person that may appear in the form of an animal. Winterbourne states that "The shaman's journey through the different parts of the cosmos is symbolized by the hamingja concept of the shape-shifting soul, and gains another symbolic dimension for the Norse soul in the account of Oðin's ravens, Huginn and Muninn." In response to Simek's criticism of attempts to interpret the ravens "philosophically", Winterbourne says that "such speculations [...] simply strengthen the conceptual significance made plausible by other features of the mythology" and that the names Huginn and Muninn "demand more explanation than is usually provided."

The Heliand, an Old Saxon adaptation of the New Testament from the 9th century, differs from the New Testament in that an explicit reference is made to a dove sitting on the shoulder of Christ. Regarding this, G. Ronald Murphy says "In placing the powerful white dove not just above Christ, but right on his shoulder, the Heliand author has portrayed Christ, not only as the Son of the All-Ruler, but also as a new Woden. This deliberate image of Christ triumphantly astride the land with the magnificent bird on his shoulders (the author is perhaps a bit embarrassed that the bird is an unwarlike dove!) is an image intended to calm the fears and longings of those who mourn the loss of Woden and who want to return to the old religion's symbols and ways. With this image, Christ becomes a Germanic god, one into whose ears the Spirit of the Almighty whispers".

Bernd Heinrich theorizes that Huginn and Muninn, along with Odin and his wolves Geri and Freki, reflect a symbiosis observed in the natural world among ravens, wolves, and humans on the hunt:
 * In a biological symbiosis one organism typically shores up some weakness or deficiency of the other(s). As in such a symbiosis, Odin the father of all humans and gods, though in human form was imperfect by himself. As a separate entity he lacked depth perception (being one-eyed) and he was apparently also uninformed and forgetful. But his weaknesses were compensated by his ravens, Hugin (mind) and Munin (memory) who were part of him. They perched on his shoulders and reconnoitered to the ends of the earth each day to return in the evening and tell him the news. He also had two wolves at his side, and the man/god-raven-wolf association was like one single organism in which the ravens were the eyes, mind, and memory, and the wolves the providers of meat and nourishment. As god, Odin was the ethereal part—he only drank wine and spoke only in poetry. I wondered if the Odin myth was a metaphor that playfully and poetically encapsulates ancient knowledge of our prehistoric past as hunters in association with two allies to produce a powerful hunting alliance. It would reflect a past that we have long forgotten and whose meaning has been obscured and badly frayed as we abandoned our hunting cultures to become herders and agriculturists, to whom ravens act as competitors.

title: Huginn and Muninn


text:
Heat engine

A heat engine is a system that converts heat to usable energy, particularly mechanical energy, which can then be used to do mechanical work. While originally conceived in the context of mechanical energy, the concept of the heat engine has been applied to various other kinds of energy, particularly electrical, since at least the late 19th century. The heat engine does this by bringing a working substance from a higher state temperature to a lower state temperature. A heat source generates thermal energy that brings the working substance to the higher temperature state. The working substance generates work in the working body of the engine while transferring heat to the colder sink until it reaches a lower temperature state. During this process some of the thermal energy is converted into work by exploiting the properties of the working substance. The working substance can be any system with a non-zero heat capacity, but it usually is a gas or liquid. During this process, some heat is normally lost to the surroundings and is not converted to work. Also, some energy is unusable because of friction and drag.

In general, an engine is any machine that converts energy to mechanical work. Heat engines distinguish themselves from other types of engines by the fact that their efficiency is fundamentally limited by Carnot's theorem of thermodynamics. Although this efficiency limitation can be a drawback, an advantage of heat engines is that most forms of energy can be easily converted to heat by processes like exothermic reactions (such as combustion), nuclear fission, absorption of light or energetic particles, friction, dissipation and resistance. Since the heat source that supplies thermal energy to the engine can thus be powered by virtually any kind of energy, heat engines cover a wide range of applications.

Heat engines are often confused with the cycles they attempt to implement. Typically, the term "engine" is used for a physical device and "cycle" for the models.

Overview
In thermodynamics, heat engines are often modeled using a standard engineering model such as the Otto cycle. The theoretical model can be refined and augmented with actual data from an operating engine, using tools such as an indicator diagram. Since very few actual implementations of heat engines exactly match their underlying thermodynamic cycles, one could say that a thermodynamic cycle is an ideal case of a mechanical engine. In any case, fully understanding an engine and its efficiency requires a good understanding of the (possibly simplified or idealised) theoretical model, the practical nuances of an actual mechanical engine and the discrepancies between the two.

In general terms, the larger the difference in temperature between the hot source and the cold sink, the larger is the potential thermal efficiency of the cycle. On Earth, the cold side of any heat engine is limited to being close to the ambient temperature of the environment, or not much lower than 300 kelvin, so most efforts to improve the thermodynamic efficiencies of various heat engines focus on increasing the temperature of the source, within material limits. The maximum theoretical efficiency of a heat engine (which no engine ever attains) is equal to the temperature difference between the hot and cold ends divided by the temperature at the hot end, each expressed in absolute temperature.

The efficiency of various heat engines proposed or used today has a large range:
 * 3% (97 percent waste heat using low quality heat) for the ocean thermal energy conversion (OTEC) ocean power proposal
 * 25% for most automotive gasoline engines
 * 49% for a supercritical coal-fired power station such as the Avedøre Power Station
 * 60% for a combined cycle gas turbine

The efficiency of these processes is roughly proportional to the temperature drop across them. Significant energy may be consumed by auxiliary equipment, such as pumps, which effectively reduces efficiency.

Examples
Although some cycles have a typical combustion location (internal or external), they can often be implemented with the other. For example, John Ericsson developed an external heated engine running on a cycle very much like the earlier Diesel cycle. In addition, externally heated engines can often be implemented in open or closed cycles. In a closed cycle the working fluid is retained within the engine at the completion of the cycle whereas is an open cycle the working fluid is either exchanged with the environment together with the products of combustion in the case of the internal combustion engine or simply vented to the environment in the case of external combustion engines like steam engines and turbines.

Everyday examples
Everyday examples of heat engines include the thermal power station, internal combustion engine, firearms, refrigerators and heat pumps. Power stations are examples of heat engines run in a forward direction in which heat flows from a hot reservoir and flows into a cool reservoir to produce work as the desired product. Refrigerators, air conditioners and heat pumps are examples of heat engines that are run in reverse, i.e. they use work to take heat energy at a low temperature and raise its temperature in a more efficient way than the simple conversion of work into heat (either through friction or electrical resistance). Refrigerators remove heat from within a thermally sealed chamber at low temperature and vent waste heat at a higher temperature to the environment and heat pumps take heat from the low temperature environment and 'vent' it into a thermally sealed chamber (a house) at higher temperature.

In general heat engines exploit the thermal properties associated with the expansion and compression of gases according to the gas laws or the properties associated with phase changes between gas and liquid states.

Earth's heat engine
Earth's atmosphere and hydrosphere—Earth's heat engine—are coupled processes that constantly even out solar heating imbalances through evaporation of surface water, convection, rainfall, winds and ocean circulation, when distributing heat around the globe.

A Hadley cell is an example of a heat engine. It involves the rising of warm and moist air in the earth's equatorial region and the descent of colder air in the subtropics creating a thermally driven direct circulation, with consequent net production of kinetic energy.

Phase-change cycles
In phase change cycles and engines, the working fluids are gases and liquids. The engine converts the working fluid from a gas to a liquid, from liquid to gas, or both, generating work from the fluid expansion or compression.
 * Rankine cycle (classical steam engine)
 * Regenerative cycle (steam engine more efficient than Rankine cycle)
 * Organic Rankine cycle (Coolant changing phase in temperature ranges of ice and hot liquid water)
 * Vapor to liquid cycle (drinking bird, injector, Minto wheel)
 * Liquid to solid cycle (frost heaving – water changing from ice to liquid and back again can lift rock up to 60 cm.)
 * Solid to gas cycle (firearms – solid propellants combust to hot gases.)

Gas-only cycles
In these cycles and engines the working fluid is always a gas (i.e., there is no phase change):
 * Carnot cycle (Carnot heat engine)
 * Ericsson cycle (Caloric Ship John Ericsson)
 * Stirling cycle (Stirling engine, thermoacoustic devices)
 * Internal combustion engine (ICE):
 * Otto cycle (e.g. gasoline/petrol engine)
 * Diesel cycle (e.g. Diesel engine)
 * Atkinson cycle (Atkinson engine)
 * Brayton cycle or Joule cycle originally Ericsson cycle (gas turbine)
 * Lenoir cycle (e.g., pulse jet engine)
 * Miller cycle (Miller engine)

Liquid-only cycles
In these cycles and engines the working fluid are always like liquid:
 * Stirling cycle (Malone engine)

Electron cycles

 * Johnson thermoelectric energy converter
 * Thermoelectric (Peltier–Seebeck effect)
 * Thermogalvanic cell
 * Thermionic emission
 * Thermotunnel cooling

Magnetic cycles

 * Thermo-magnetic motor (Tesla)

Cycles used for refrigeration
A domestic refrigerator is an example of a heat pump: a heat engine in reverse. Work is used to create a heat differential. Many cycles can run in reverse to move heat from the cold side to the hot side, making the cold side cooler and the hot side hotter. Internal combustion engine versions of these cycles are, by their nature, not reversible.

Refrigeration cycles include:
 * Air cycle machine
 * Gas-absorption refrigerator
 * Magnetic refrigeration
 * Stirling cryocooler
 * Vapor-compression refrigeration
 * Vuilleumier cycle

Evaporative heat engines
The Barton evaporation engine is a heat engine based on a cycle producing power and cooled moist air from the evaporation of water into hot dry air.

Mesoscopic heat engines
Mesoscopic heat engines are nanoscale devices that may serve the goal of processing heat fluxes and perform useful work at small scales. Potential applications include e.g. electric cooling devices. In such mesoscopic heat engines, work per cycle of operation fluctuates due to thermal noise. There is exact equality that relates average of exponents of work performed by any heat engine and the heat transfer from the hotter heat bath. This relation transforms the Carnot's inequality into exact equality. This relation is also a Carnot cycle equality

Efficiency
The efficiency of a heat engine relates how much useful work is output for a given amount of heat energy input.

From the laws of thermodynamics, after a completed cycle:
 * $$ W + Q = \Delta_{cycle}U = 0 $$
 * and therefore
 * $$ W = -Q = - (Q_c + Q_h) $$
 * where
 * $$ W = -\oint PdV $$ is the net work extracted from the engine in one cycle. (It is negative, in the IUPAC convention, since work is done by the engine.)
 * $$ Q_h > 0 $$ is the heat energy taken from the high temperature heat source in the surroundings in one cycle. (It is positive since heat energy is added to the engine.)
 * $$ Q_c = -|Q_c|<0 $$ is the waste heat given off by the engine to the cold temperature heat sink. (It is negative since heat is lost by the engine to the sink.)

In other words, a heat engine absorbs heat energy from the high temperature heat source, converting part of it to useful work and giving off the rest as waste heat to the cold temperature heat sink.

In general, the efficiency of a given heat transfer process is defined by the ratio of "what is taken out" to "what is put in". (For a refrigerator or heat pump, which can be considered as a heat engine run in reverse, this is the coefficient of performance and it is ≥ 1.) In the case of an engine, one desires to extract work and has to put in heat $$ Q_h $$, for instance from combustion of a fuel, so the engine efficiency is reasonably defined as
 * $$\eta = \frac{|W|}{Q_h} = \frac{Q_h + Q_c}{Q_h} = 1 + \frac{Q_c}{Q_h} = 1 - \frac{|Q_c|}{Q_h}$$

The efficiency is less than 100% because of the waste heat $$ Q_c<0 $$ unavoidably lost to the cold sink (and corresponding compression work put in) during the required recompression at the cold temperature before the power stroke of the engine can occur again.

The theoretical maximum efficiency of any heat engine depends only on the temperatures it operates between. This efficiency is usually derived using an ideal imaginary heat engine such as the Carnot heat engine, although other engines using different cycles can also attain maximum efficiency. Mathematically, after a full cycle, the overall change of entropy is zero:

$$\ \ \ \Delta S_h + \Delta S_c = \Delta_{cycle} S = 0$$

Note that $$\Delta S_h$$ is positive because isothermal expansion in the power stroke increases the multiplicity of the working fluid while $$\Delta S_c$$ is negative since recompression decreases the multiplicity. If the engine is ideal and runs reversibly, $$ Q_h = T_h\Delta S_h $$ and $$ Q_c = T_c\Delta S_c  $$, and thus

$$ Q_h / T_h + Q_c / T_c = 0 $$,

which gives $$ Q_c /Q_h = -T_c / T_h $$ and thus the Carnot limit for heat-engine efficiency,
 * $$\eta_\text{max} = 1 - \frac{T_c}{T_h}$$

where $$T_h$$ is the absolute temperature of the hot source and $$T_c$$ that of the cold sink, usually measured in kelvins.

The reasoning behind this being the maximal efficiency goes as follows. It is first assumed that if a more efficient heat engine than a Carnot engine is possible, then it could be driven in reverse as a heat pump. Mathematical analysis can be used to show that this assumed combination would result in a net decrease in entropy. Since, by the second law of thermodynamics, this is statistically improbable to the point of exclusion, the Carnot efficiency is a theoretical upper bound on the reliable efficiency of any thermodynamic cycle.

Empirically, no heat engine has ever been shown to run at a greater efficiency than a Carnot cycle heat engine.

Figure 2 and Figure 3 show variations on Carnot cycle efficiency with temperature. Figure 2 indicates how efficiency changes with an increase in the heat addition temperature for a constant compressor inlet temperature. Figure 3 indicates how the efficiency changes with an increase in the heat rejection temperature for a constant turbine inlet temperature.

Endo-reversible heat-engines
By its nature, any maximally efficient Carnot cycle must operate at an infinitesimal temperature gradient; this is because any transfer of heat between two bodies of differing temperatures is irreversible, therefore the Carnot efficiency expression applies only to the infinitesimal limit. The major problem is that the objective of most heat-engines is to output power, and infinitesimal power is seldom desired.

A different measure of ideal heat-engine efficiency is given by considerations of endoreversible thermodynamics, where the system is broken into reversible subsystems, but with non reversible interactions between them. A classical example is the Curzon–Ahlborn engine, very similar to a Carnot engine, but where the thermal reservoirs at temperature $$T_h$$ and $$T_c$$ are allowed to be different from the temperatures of the substance going through the reversible Carnot cycle: $$T'_h$$ and $$T'_c$$. The heat transfers between the reservoirs and the substance are considered as conductive (and irreversible) in the form $$dQ_{h,c}/dt = \alpha (T_{h,c}-T'_{h,c})$$. In this case, a tradeoff has to be made between power output and efficiency. If the engine is operated very slowly, the heat flux is low, $$T\approx T'$$ and the classical Carnot result is found
 * $$\eta = 1 - \frac{T_c}{T_h}$$,

but at the price of a vanishing power output. If instead one chooses to operate the engine at its maximum output power, the efficiency becomes
 * $$\eta = 1 - \sqrt{\frac{T_c}{T_h}}$$ (Note: T in units of K or °R)

This model does a better job of predicting how well real-world heat-engines can do (Callen 1985, see also endoreversible thermodynamics):

As shown, the Curzon–Ahlborn efficiency much more closely models that observed.

History
Heat engines have been known since antiquity but were only made into useful devices at the time of the industrial revolution in the 18th century. They continue to be developed today.

Enhancements
Engineers have studied the various heat-engine cycles to improve the amount of usable work they could extract from a given power source. The Carnot cycle limit cannot be reached with any gas-based cycle, but engineers have found at least two ways to bypass that limit and one way to get better efficiency without bending any rules:
 * 1) Increase the temperature difference in the heat engine. The simplest way to do this is to increase the hot side temperature, which is the approach used in modern combined-cycle gas turbines. Unfortunately, physical limits (such as the melting point of the materials used to build the engine) and environmental concerns regarding NOx production (if the heat source is combustion with ambient air) restrict the maximum temperature on workable heat-engines. Modern gas turbines run at temperatures as high as possible within the range of temperatures necessary to maintain acceptable NOx output . Another way of increasing efficiency is to lower the output temperature. One new method of doing so is to use mixed chemical working fluids, then exploit the changing behavior of the mixtures. One of the most famous is the so-called Kalina cycle, which uses a 70/30 mix of ammonia and water as its working fluid. This mixture allows the cycle to generate useful power at considerably lower temperatures than most other processes.
 * 2) Exploit the physical properties of the working fluid. The most common such exploitation is the use of water above the critical point (supercritical water). The behavior of fluids above their critical point changes radically, and with materials such as water and carbon dioxide it is possible to exploit those changes in behavior to extract greater thermodynamic efficiency from the heat engine, even if it is using a fairly conventional Brayton or Rankine cycle. A newer and very promising material for such applications is supercritical CO2. SO2 and xenon have also been considered for such applications. Downsides include issues of corrosion and erosion, the different chemical behavior above and below the critical point, the needed high pressures and – in the case of sulfur dioxide and to a lesser extent carbon dioxide – toxicity. Among the mentioned compounds xenon is least suitable for use in a nuclear reactor due to the high neutron absorption cross section of almost all isotopes of xenon, whereas carbon dioxide and water can also double as a neutron moderator for a thermal spectrum reactor.
 * 3) Exploit the chemical properties of the working fluid. A fairly new and novel exploit is to use exotic working fluids with advantageous chemical properties. One such is nitrogen dioxide (NO2), a toxic component of smog, which has a natural dimer as di-nitrogen tetraoxide (N2O4). At low temperature, the N2O4 is compressed and then heated. The increasing temperature causes each N2O4 to break apart into two NO2 molecules. This lowers the molecular weight of the working fluid, which drastically increases the efficiency of the cycle. Once the NO2 has expanded through the turbine, it is cooled by the heat sink, which makes it recombine into N2O4. This is then fed back by the compressor for another cycle. Such species as aluminium bromide (Al2Br6), NOCl, and Ga2I6 have all been investigated for such uses. To date, their drawbacks have not warranted their use, despite the efficiency gains that can be realized.

Heat engine processes
Each process is one of the following:
 * isothermal (at constant temperature, maintained with heat added or removed from a heat source or sink)
 * isobaric (at constant pressure)
 * isometric/isochoric (at constant volume), also referred to as iso-volumetric
 * adiabatic (no heat is added or removed from the system during adiabatic process)
 * isentropic (reversible adiabatic process, no heat is added or removed during isentropic process)

title: Heat engine


text:
Heimdall

In Norse mythology, Heimdall (from Old Norse Heimdallr) is a god. He is the son of Odin and nine mothers. Heimdall keeps watch for invaders and the onset of Ragnarök from his dwelling Himinbjörg, where the burning rainbow bridge Bifröst meets the sky. He is attested as possessing foreknowledge and keen senses, particularly eyesight and hearing. The god and his possessions are described in enigmatic manners. For example, Heimdall is golden-toothed, "the head is called his sword," and he is "the whitest of the gods."

Heimdall possesses the resounding horn Gjallarhorn and the golden-maned horse Gulltoppr, along with a store of mead at his dwelling. He is the son of Nine Mothers, and he is said to be the originator of social classes among humanity. Other notable stories include the recovery of Freyja's treasured possession Brísingamen while doing battle in the shape of a seal with Loki. The antagonistic relationship between Heimdall and Loki is notable, as they are foretold to kill one another during the events of Ragnarök. Heimdallr is also known as Rig, Hallinskiði, Gullintanni, and Vindlér or Vindhlér.

Heimdall is attested in the Poetic Edda, compiled in the 13th century from earlier traditional material; in the Prose Edda and Heimskringla, both written in the 13th century; in the poetry of skalds; and on an Old Norse runic inscription found in England. Two lines of an otherwise lost poem about the god, Heimdalargaldr, survive. Due to the enigmatic nature of these attestations, scholars have produced various theories about the nature of the god, including his relation to sheep, borders, and waves.

Names and etymology
The etymology of the name is obscure, but 'the one who illuminates the world' has been proposed. Heimdallr may be connected to Mardöll, one of Freyja's names. Heimdallr and its variants are usually anglicized as Heimdall (with the nominative -r dropped).

Heimdall is attested as having three other names; Hallinskiði, Gullintanni, and Vindlér or Vindhlér. The name Hallinskiði is obscure, but has resulted in a series of attempts at deciphering it. Gullintanni literally means 'the one with the golden teeth'. Vindlér (or Vindhlér) translates as either 'the one protecting against the wind' or 'wind-sea'. All three have resulted in numerous theories about the god.

Saltfleetby spindle whorl inscription
A lead spindle whorl bearing an Old Norse Younger Futhark inscription that mentions Heimdall was discovered in Saltfleetby, England on September 1, 2010. The spindle whorl itself is dated from the year 1000 to 1100 AD. On the inscription, the god Heimdallr is mentioned alongside the god Odin and Þjálfi, a name of one of the god Thor's servants. Regarding the inscription reading, John Hines of Cardiff University comments that there is "quite an essay to be written over the uncertainties of translation and identification here; what are clear, and very important, are the names of two of the Norse gods on the side, Odin and Heimdallr, while Þjalfi (masculine, not the feminine in -a) is the recorded name of a servant of the god Thor."

Poetic Edda
In the Poetic Edda, Heimdall is attested in six poems; Völuspá, Grímnismál, Lokasenna, Þrymskviða, Rígsþula, and Hrafnagaldr Óðins.

Heimdall is mentioned three times in Völuspá. In the first stanza of the poem, the undead völva reciting the poem calls out for listeners to be silent and refers to the Norse god:

This stanza has led to various scholarly interpretations. The "holy races" have been considered variously as either humanity or the gods. The notion of humanity as "Heimdall's sons" is otherwise unattested and has also resulted in various interpretations. Some scholars have pointed to the prose introduction to the poem Rígsþula, where Heimdall is said to have once gone about people, slept between couples, and so doled out classes among them (see Rígsthula section below).

Later in Völuspá, the völva foresees the events of Ragnarök and the role in which Heimdall and Gjallarhorn will play at its onset; Heimdall will raise his horn and blow loudly. Due to manuscript differences, translations of the stanza vary:

Regarding this stanza, scholar Andy Orchard comments that the name Gjallarhorn may here mean "horn of the river Gjöll" as "Gjöll is the name of one of the rivers of the Underworld, whence much wisdom is held to derive", but notes that in the poem Grímnismál Heimdall is said to drink fine mead in his heavenly home Himinbjörg.

Earlier in the same poem, the völva mentions a scenario involving the hearing or horn (depending on translation of the Old Norse noun hljóð—translations bolded below for the purpose of illustration) of the god Heimdall:

Scholar Paul Schach comments that the stanzas in this section of  Völuspá are "all very mysterious and obscure, as it was perhaps meant to be". Schach details that "Heimdallar hljóð has aroused much speculation. Snorri [in the Prose Edda] seems to have confused this word with gjallarhorn, but there is otherwise no attestation of the use of hljóð in the sense of 'horn' in Icelandic. Various scholars have read this as "hearing" rather than "horn".

Scholar Carolyne Larrington comments that if "hearing" rather than "horn" is understood to appear in this stanza, the stanza indicates that Heimdall, like Odin, has left a body part in the well; his ear. Larrington says that "Odin exchanged one of his eyes for wisdom from Mimir, guardian of the well, while Heimdall seems to have forfeited his ear."

In the poem Grímnismál, Odin (disguised as Grímnir), tortured, starved and thirsty, tells the young Agnar of a number of mythological locations. The eighth location he mentions is Himinbjörg, where he says that Heimdall drinks fine mead:

Regarding the above stanza, Henry Adams Bellows comments that "in this stanza the two functions of Heimdall—as father of humanity [ . . . ] and as warder of the gods—seem both to be mentioned, but the second line in the manuscripts is apparently in bad shape, and in the editions it is more or less conjecture".

In the poem Lokasenna, Loki flyts with various gods who have met together to feast. At one point during the exchanges, the god Heimdall says that Loki is drunk and witless, and asks Loki why he won't stop speaking. Loki tells Heimdall to be silent, that he was fated a "hateful life", that Heimdall must always have a muddy back, and that he must serve as watchman of the gods. The goddess Skaði interjects and the flyting continues in turn.

The poem Þrymskviða tells of Thor's loss of his hammer, Mjöllnir, to the jötnar and quest to get it back. At one point in the tale, the gods gather at the thing and debate how to get Thor's hammer back from the jötnar, who demand the beautiful goddess Freyja in return for it. Heimdall advises that they simply dress Thor up as Freyja, during which he is described as hvítastr ása (translations of the phrase vary below) and is said to have foresight like the Vanir, a group of gods:

Regarding Heimdall's status as hvítastr ása (variously translated above as "brightest" (Thorpe), "whitest" (Bellows), and "most glittering" (Dodds)) and the comparison to the Vanir, scholar John Lindow comments that there are no other indications of Heimdall being considered among the Vanir (on Heimdall's status as "hvítastr ása ", see "scholarly reception" below).

The introductory prose to the poem Rígsþula says that "people say in the old stories" that Heimdall, described as a god among the Æsir, once fared on a journey. Heimdall wandered along a seashore, and referred to himself as Rígr. In the poem, Rígr, who is described as a wise and powerful god, walks in the middle of roads on his way to steads, where he meets a variety of couples and dines with them, giving them advice and spending three nights at a time between them in their bed. The wives of the couples become pregnant, and from them come the various classes of humanity.

Eventually a warrior home produces a promising boy, and as the boy grows older, Rígr comes out of a thicket, teaches the boy runes, gives him a name, and proclaims him to be his son. Rígr tells him to strike out and get land for himself. The boy does so, and so becomes a great war leader with many estates. He marries a beautiful woman and the two have many children and are happy. One of the children eventually becomes so skilled that he is able to share in runic knowledge with Heimdall, and so earns the title of Rígr himself. The poem breaks off without further mention of the god.

Prose Edda

In the Prose Edda, Heimdall is mentioned in the books Gylfaginning, Skáldskaparmál, and Háttatal. In Gylfaginning, the enthroned figure of High tells the disguised mythical king Gangleri of various gods, and, in chapter 25, mentions Heimdall. High says that Heimdall is known as "the white As", is "great and holy", and that nine maidens, all sisters, gave birth to him. Heimdall is called Hallinskiði and Gullintanni, and he has gold teeth. High continues that Heimdall lives in "a place" called Himinbjörg and that it is near Bifröst. Heimdall is the watchman of the gods, and he sits on the edge of heaven to guard the Bifröst bridge from the berg jötnar. Heimdall requires less sleep than a bird, can see at night just as well as if it were day, and for over a hundred leagues. Heimdall's hearing is also quite keen; he can hear grass as it grows on the earth, wool as it grows on sheep, and anything louder. Heimdall possesses a trumpet, Gjallarhorn, that, when blown, can be heard in all worlds, and "the head is referred to as Heimdall's sword". High then quotes the above-mentioned Grímnismál stanza about Himinbjörg and provides two lines from the otherwise lost poem about Heimdall, Heimdalargaldr, in which he proclaims himself to be the son of Nine Mothers.

In chapter 49, High tells of the god Baldr's funeral procession. Various deities are mentioned as having attended, including Heimdall, who there rode his horse Gulltopr.

In chapter 51, High foretells the events of Ragnarök. After the enemies of the gods will gather at the plain Vígríðr, Heimdall will stand and mightily blow into Gjallarhorn. The gods will awake and assemble together at the thing. At the end of the battle between various gods and their enemies, Heimdall will face Loki and they will kill one another. After, the world will be engulfed in flames. High then quotes the above-mentioned stanza regarding Heimdall raising his horn in Völuspá.

At the beginning of Skáldskaparmál, Heimdall is mentioned as having attended a banquet in Asgard with various other deities. Later in the book, Húsdrápa, a poem by 10th century skald Úlfr Uggason, is cited, during which Heimdall is described as having ridden to Baldr's funeral pyre.

In chapter 8, means of referring to Heimdall are provided; "son of nine mothers", "guardian of the gods", "the white As" (see Poetic Edda discussion regarding hvítastr ása above), "Loki's enemy", and "recoverer of Freyja's necklace". The section adds that the poem Heimdalargaldr is about him, and that, since the poem, "the head has been called Heimdall's doom: man's doom is an expression for sword". Hiemdallr is the owner of Gulltoppr, is also known as Vindhlér, and is a son of Odin. Heimdall visits Vágasker and Singasteinn and there vied with Loki for Brísingamen. According to the chapter, the skald Úlfr Uggason composed a large section of his Húsdrápa about these events and that Húsdrápa says that the two were in the shape of seals. A few chapters later, ways of referring to Loki are provided, including "wrangler with Heimdall and Skadi", and section of Úlfr Uggason's Húsdrápa is then provided in reference:

"Renowned defender [Heimdall] of the powers' way [Bifrost], kind of counsel, competes with Farbauti's terribly sly son at Singastein. Son of eight mothers plus one, might of mood, is first to get hold of the beautiful sea-kidney [jewel, Brisingamen]. I announce it in strands of praise."

The chapter points out that in the above Húsdrápa section Heimdall is said to be the son of nine mothers.

Heimdall is mentioned once in Háttatal. There, in a composition by Snorri Sturluson, a sword is referred to as "Vindhlér's helmet-filler", meaning "Heimdall's head".

Heimskringla
In Ynglinga saga compiled in Heimskringla, Snorri presents a euhemerized origin of the Norse gods and rulers descending from them. In chapter 5, Snorri asserts that the Æsir settled in what is now Sweden and built various temples. Snorri writes that Odin settled in Lake Logrin "at a place which formerly was called Sigtúnir. There he erected a large temple and made sacrifices according to the custom of the Æsir. He took possession of the land as far as he had called it Sigtúnir. He gave dwelling places to the temple priests." Snorri adds that, after this, Njörðr dwelt in Nóatún, Freyr dwelt in Uppsala, Heimdall at Himinbjörg, Thor at Þrúðvangr, Baldr at Breiðablik and that to everyone Odin gave fine estates.

Visual depictions
A figure holding a large horn to his lips and clasping a sword on his hip appears on a stone cross from the Isle of Man. Some scholars have theorized that this figure is a depiction of Heimdall with Gjallarhorn.

A 9th or 10th century Gosforth Cross in Cumbria, England depicts a figure holding a horn and a sword standing defiantly before two open-mouthed beasts. This figure has been often theorized as depicting Heimdall with Gjallarhorn.

Scholarly reception
Heimdall's attestations have proven troublesome and enigmatic to interpret for scholars. A variety of sources describe the god as born from Nine Mothers, a puzzling description (for more in-depth discussion, see Nine Mothers of Heimdallr). Various scholars have interpreted this as a reference to the Nine Daughters of Ægir and Rán, personifications of waves. This would therefore mean Heimdall is born from the waves, an example of a deity born from the sea.

In the textual corpus, Heimdall is frequently described as maintaining a particular association with boundaries, borders, and liminal spaces, both spatial and temporal. For example, Gylfaginning describes the god as guarding the border of the land of the gods, Heimdall meets humankind at a coast, and, if accepted as describing Heimdall, Völuspá hin skamma describes him as born 'at the edge of the world' in 'days of yore' by the Nine Daughters of Ægir and Rán, and it is Heimdall's horn that signals the transition to the events of Ragnarök.

Additionally, Heimdall has a particular association with male sheep, rams. A form of the deity's name, Heimdali, occurs twice as a name for 'ram' in Skáldskaparmál, as does Heimdall's name Hallinskíði. Heimdall's unusual physical description has also been seen by various scholars as fitting this association: As mentioned above, Heimdall is described as gold-toothed (by way of his name Gullintanni), as having the ability to hear grass grow and the growth of wool on sheep, and as owning a sword called 'head' (rams have horns on their heads). This may mean that Heimdall was associated with the ram perhaps as a sacred and/or sacrificial animal or that the ancient Scandinavians may have conceived of him as having been a ram in appearance.

All of these topics—Heimdall's birth, his association with borders and boundaries, and his connection to sheep—have led to significant discussion among scholars. For example, influential philologist and folklorist Georges Dumézil, comparing motifs and clusters of motifs in western Europe, proposes the following explanation for Heimdall's birth and association with rams (italics are Dumézil's own):

"Many folklores compare waves which, under a strong wind, are topped with white foam ... to different animals, especially to horses or mares, to cows or bulls, to dogs or sheep. We say in France, 'moutons, moutonner, moutannant' (white sheep, to break into white sheep, breaking into white sheep) and the English 'white horses.' The modern Welsh, like the Irish, speak of 'white mares (cesyg)' but the old tradition linked to the name of Gwenhidwy, as in French, Basque, and other folklores, turned these waves into sheep. Conversely, in many countries the sailors or the coast dwellers attribute to certain wave sequences particular qualities or forces, sometimes, even, ... a supernatural power: it happens that the third, or the ninth, or the tenth wave is the biggest, or the most dangerous, or the noisiest or the most powerful. But what I have found nowhere else but in the Welsh tradition concerning Gwenhidwy is a combination of these two beliefs, the final result of which is to make the ninth wave the ram of the simple ewes that are the eight preceding waves.

This concept furnishes a satisfactory explanation of that section of Heimdall's dossier which we are considering: it allows us to combine his birth—nine mothers who are waves, at the confines of the earth—and his attributes of a ram. We understand that whatever his mythical value and functions were, the scene of his birth made him, in the sea's white frothing, the ram produced by the ninth wave."

In popular culture
As with many aspects of Norse mythology, Heimdall has appeared in many modern works. Heimdall appears as a character in Marvel Comics and is portrayed in the film versions by English actor Idris Elba.

Heimdall is the namesake of a crater on Callisto, a moon of Jupiter.

Heimdall is the protagonist of an eponymous video game released in 1991 and its 1994 sequel, Heimdall 2. In the 2002 Ensemble Studios game Age of Mythology, Heimdall is one of 12 gods the Norse can choose to worship. Heimdallr is one of the playable gods in the multiplayer online battle arena game Smite. Heimdall also appears as an antagonist in the 2022 action-adventure video game God of War Ragnarök and is played by the American actor Scott Porter.

title: Heimdall