Quantum gravity is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics, where quantum effects cannot be ignored, such as near compact astrophysical objects where the effects of gravity are strong. The current understanding of gravity is based on Albert Einstein's general theory of relativity, formulated within the framework of classical physics. On the other hand, the other three fundamental forces of physics are described within the framework of quantum mechanics and quantum field theory, radically different formalisms for describing physical phenomena, it is sometimes argued that a quantum mechanical description of gravity is necessary on the grounds that one cannot couple a classical system to a quantum one. While a quantum theory of gravity may be needed to reconcile general relativity with the principles of quantum mechanics, difficulties arise when applying the usual prescriptions of quantum field theory to the force of gravity via hypothesised graviton bosons.
The problem is that the theory one gets in this way is not renormalizable — it predicts infinite values for some observable properties, such as the mass of particles, therefore cannot be used to make meaningful physical predictions of those properties. As a result, theorists have taken up more radical approaches to the problem of quantum gravity, the most popular approaches being string theory and loop quantum gravity. Although some quantum gravity theories, such as string theory, try to unify gravity with the other fundamental forces, such as loop quantum gravity, make no such attempt. Speaking, the aim of quantum gravity is only to describe the quantum behavior of the gravitational field and should not be confused with the objective of unifying all fundamental interactions into a single mathematical framework. A quantum field theory of gravity, unified with a grand unified theory is sometimes referred to as a theory of everything. While any substantial improvement into the present understanding of gravity would aid further work towards unification, the study of quantum gravity is a field in its own right with various branches having different approaches to unification.
One of the difficulties of formulating a quantum gravity theory is that quantum gravitational effects only appear at length scales near the Planck scale, around 10−35 meters, a scale far smaller, equivalently far larger in energy, than those accessible by high energy particle accelerators. Therefore, physicists lack experimental data which could distinguish between the competing theories which have been proposed and thus thought experiment approaches are suggested as a testing tool for these theories. Much of the difficulty in meshing these theories at all energy scales comes from the different assumptions that these theories make on how the universe works. General relativity models gravity as curvature of spacetime: in the slogan of John Archibald Wheeler, "Spacetime tells matter how to move. On the other hand, quantum field theory is formulated in the flat spacetime used in special relativity. No theory has yet proven successful in describing the general situation where the dynamics of matter, modeled with quantum mechanics, affect the curvature of spacetime.
If one attempts to treat gravity as another quantum field, the resulting theory is not renormalizable. In the simpler case where the curvature of spacetime is fixed a priori, developing quantum field theory becomes more mathematically challenging, many ideas physicists use in quantum field theory on flat spacetime are no longer applicable, it is hoped that a theory of quantum gravity would allow us to understand problems of high energy and small dimensions of space, such as the behavior of black holes, the origin of the universe. At present, one of the deepest problems in theoretical physics is harmonizing the theory of general relativity, which describes gravitation and applies to large-scale structures, with quantum mechanics, which describes the other three fundamental forces acting on the atomic scale; this problem must be put in the proper context, however. In particular, contrary to the popular claim that quantum mechanics and general relativity are fundamentally incompatible, one can demonstrate that the structure of general relativity follows from the quantum mechanics of interacting theoretical spin-2 massless particles.
The observation that all fundamental forces except gravity have one or more known messenger particles leads researchers to believe that at least one must exist. This hypothetical particle is known as the graviton; the predicted find would result in the classification of the graviton as a force particle similar to the photon of the electromagnetic interaction. Many of the accepted notions of a unified theory of physics since the 1970s assume, to some degree depend upon, the existence of the graviton; these include string theory, superstring theory, M-theory. Detection of gravitons would validate these various lines of research to unify quantum mechanics and relativity theory; the Weinberg–Witten theorem places some constraints on theories in which the graviton is a composite particle. The dilaton made its first appearance in Kaluza–Klein theory, a five-dimensional theory that combined gravitation and electromagnetism, it appears in string theory. However, it's become central to the lower-dimensional many-bodied gravity problem based on the field theoretic approach of Roman Jackiw.
The impetus arose from the fact that complete analytical solutions for the metric of a cova
The Afghan–Sikh wars were a series of wars between the Islamic Durrani Empire, the Sikh Empire. The conflict had its origins stemming from the days of the Dal Khalsa; the Sikh Confederacy had achieved independence from the Mughal Empire in 1716, expanded at its expense in the following decades, despite the Sikh holocaust of 1746. The Afsharid Persian emperor Nader Shah's invasion of the Mughal Empire dealt a heavy blow to the Mughals, but after Nader's death in 1747, the Durrani Empire declared its independence from Persia. Four years this new Afghan state came into conflict with the Sikh alliance; this battle started with the Battle of Attock known as the Battle of Chuch or the Battle of Haidru. This was the significant victory of the Sikhs over the Afghans. In the battle's aftermath, Sikhs seized control of Attock District. After his defeat at Attock, Fatteh Khan Barakzai, the vizier of Kabul, fought off an attempt by Fath-Ali Shah Qajar, the ruler of Persia, his son Ali Mirza to capture the Durrani province of Herat.
The Battle of Multan was the second battle in the Afghan–Sikh wars. It lasted from March 1818 to 2 June 1818; this battle ended the Durrani influence in the Khyber Pakhtunkhwa region, led to the Sikhs holding the city of Peshawar. The Battle of Shopian was different from the first two battles, due to it taking place in the Kashmir region, more Shopian; this was the third battle in the Afghan -- the third Sikh victory. This battle included the 1819 Kashmir expedition, which led to Kashmir being annexed to the Sikh Empire. After taking Srinagar, the Sikh army faced no major opposition in conquering Kashmir; the Sikh Empire had controlled all of Kashmir. The Battle of Nowshera wasn't fought by the Durranis, but by a Pashtun force with support of the Durranis; this was the 4th battle in the Afghan -- 4th Sikh victory. After this, the Sikhs again came in possession of Peshawar, along with the whole Khyber Pass; the Battle of Jamrud was the foremost battle within the Afghan -- Sikh wars. The Afghans had been losing their territories to Sikhs over the preceding years due to conflicts against Persia, had seen their territory shrink with the loss of the Punjab region, Multan and Khyber Pakhtunkhwa.
The loss of Peshawar was the most important as the inhabitants of the region included fellow Pashtuns and the city was the considered the second capital of Afghans, so they set to reclaim it. Hari Singh was fatally injured and died of injuries. Afghans were able to gain possession of Peshawar; the result of the battle is disputed amongst historians. Some contend the failure of the Afghans to take the fort as a victory for the Sikhs. Whereas, some state an Afghan victory, James Norris, Professor of Political Science at Texas A&M International University, states that the battle's outcome was inconclusive. Battles fought by Sikhs
Manuelita Brown is an African-American sculptor from San Diego, California. Brown has beginning through the 1990s. S. in Mathematics from Oregon State University in 1962, a teaching credential in secondary-level mathematics in 1966, a M. S. in Psychology from the University of California, San Diego in 1976. Sculpting in her own studio, she has created many portraits of noted African Americans, countless multi-cultural style sculptures in abstract, figurative realism and designs for monumental bronzes that she works through clay on armatures to the lost wax process, she retired from teaching in 2000 to pursue sculpting full-time, as noted in many publications as referenced. In 2018, Brown's work was on display at the "Legacy in Black" at the San Diego History Center in Balboa Park. Brown's name has been suggested as a possible artist for statue of Shirley Chisholm, first Black woman elected to Congress. 1993: Thurgood Marshall bust, Thurgood Marshall College, University of California, San Diego 1995: Matthew Henson bust, James E. Lewis Museum of Art, Baltimore, MD 1997: Almas del Mar, Westfield UTC 2006: Dr. Howard H. Carey bust, Neighborhood House, San Diego, CA 2008: Encinitas Child, Encinitas, CA 2008: Triton, University of California, San Diego 2015: Sojourner Truth statue, Thurgood Marshall College, University of California, San Diego 2000: Finalist, Sojourner Truth Memorial statue competition, Massachusetts 2002: Woman of Distinction, Soroptimist 2015: Villager Award - Afram Global Organization Inc, #villageprojects.net Official website
The Revolutionary Front was a far-left extremist political and militant network in Sweden. The goal of the RF was to dismantle the current society through a revolution and create a socialist state; the group fought against fascism, racism and capitalism, campaigned through violent means. The Revolutionary Front was formed in 2002 by others, it was formed after the Gothenburg riots in 2001 and had connections to the Swedish AFA but was different in that it was a strict organization and not a network. The organisation's strategy and tactics were inspired by the British Anti-Fascist Action movement. In 2014 Almgren was sentenced to five years in prison for stabbing a neo-Nazi in the back during the violent December 2013 Stockholm riots. In September 2015 the organisation dissolved. During its active years the RF committed several attacks against far-right politicians and Neo-Nazis, they filmed these actions as part of their propaganda and tactics to scare other Nazis. They broke into houses, destroying property, put axes in doors and threw smoke-bombs into apartments among other things
The Kutub al-Sittah are six books containing collections of hadith compiled by six Sunni Muslim scholars in the ninth century CE two centuries after the death of Muhammad. They are sometimes referred to as al-Sihah al-Sittah, which translates as "The Authentic Six", they were first formally grouped and defined by Ibn al-Qaisarani in the 11th century, who add Sunan ibn Majah to the list. Since they have enjoyed near-universal acceptance as part of the official canon of Sunni Islam. Not all Sunni Muslim jurisprudence scholars agree on the addition of Ibn Majah. In particular, the Malikis and Ibn al-Athir consider; the reason for the addition of Ibn Majah's Sunan is that it contains many Hadiths which do not figure in the other five, whereas all the Hadiths in the Muwatta' figure in the other Sahih books. Sunni Muslims view the six major hadith collections as their most important, though the order of authenticity varies between Madhhabs: Sahih Bukhari, collected by Imam Bukhari, includes 7,275 ahadith Sahih Muslim, collected by Muslim b. al-Hajjaj, includes 9,200 ahadith Sunan Abu Dawood, collected by Abu Dawood, includes 4,800 ahadith Jami al-Tirmidhi, collected by al-Tirmidhi, includes 3,956 ahadith Sunan al-Sughra, collected by al-Nasa'i, includes 5,270 ahadith Either:Sunan ibn Majah, collected by Ibn Majah, over 4,000 ahadith Muwatta Malik, collected by Imam Malik, 1,720 ahadith The first two referred to as the Two Sahihs as an indication of their authenticity, contain seven thousand hadiths altogether if repetitions are not counted, according to Ibn Hajar.
According to the Cambridge History of Iran: "After this period commences the age of the authors of the six canonical collections of Sunni hadith, all of whom were Persian, except Imam Malik. The authors of the six collections are as follows: Muhammad b. Isma'il al-Bukhari, the author of the Sahih Bukhari, which he composed over a period of sixteen years. Traditional sources quote Bukhari as saying that he did not record any hadith before performing ablution and praying. Bukhari died near Samarqand in 256/869–70 Muslim b. Hajjaj al-Naishapuri, who died in Nishapur in 261/874–5 and whose Sahih Muslim is second in authenticity only to that of Bukhari; some scholars rate the authenticity of Sahih Muslim more than Sahih Bukhari Abu Dawood Sulaiman b. Ash'ath al-Sijistani, a Persian but of Arab descent, who died in 275/888–9. Muhammad b.'Isa al-Tirmidhi, the author of the well-known as Sunan al-Tirmidhi, a student of Bukhari and died in 279/892–3. Abu'Abd al-Rahman al-Nasa'i, from Khurasan and died in 303/915–16.
Ibn Majah al-Qazwini, who died in 273/886–7. Malik was born the son of Anas ibn Malik and Aaliyah bint Shurayk al-Azdiyya in Medina circa 711, his family was from the al-Asbahi tribe of Yemen, but his great grandfather Abu'Amir relocated the family to Medina after converting to Islam in the second year of the Hijri calendar, or 623 CE. According to Al-Muwatta, he was tall, imposing of stature fair, with white hair and beard but bald, with a huge beard and blue eyes. In chronological order his work was compiled earlier than Sahih Bukhari, therefore Al-Muwatta is regarded in Islamic literature. Alqamah ibn Waqqas
The Arneri family were land proprietors & merchant ship owners on the Dalmatian island of Korčula, since the 15th century. Arneri Palace, placed in the Old town of Korčula is built in Venetian Gothic architecture and is one of landmarks of the island, it has a bronze knocker adorning the door representing Hercules swinging two lions by their tails. In the courtyard there is a marble draw-well, it has three pears cut into it. This symbol is the arms of the family. Andrew A. Paton an English writer spoke to Signor Arneri. Andrew Paton described him as a polite gentleman who had a white neck cloth and a broad-brimmed hat: Signor Arneri: "These three pears you see on the wall," said he, "are the arms of my family. Piruzović was the name, when, in the earlier part of the 15th century, my ancestors built this palace. All the family, fathers and brothers, used to serve in the fleets of the Republic. We became Arneri, ceased to be Piruzović; the original Patriarch of the clan was called Dobroslav Peruzzi.
He had a status of a minor nobleman. It is believed. Pertaining to their trading links with Western Bosnia and South Central Croatia, the subsequent abandonment of all trading posts towards the interiors, might have given rise to the hypothesis that the family's origin came from Bosnia. While it is likely that these activities netted them further titles, the significance of these holdings remain unclear. In 1420 the family was mentioned in the charter of the town of Korčula as the Duke/Lord of the Manor of Korčula. In 1558 the clan was awarded Venetian holdings on the Island of Hvar, thereby making them Counts there as well. Land acquisition in Brač, Trogir, Vis, etc. placed the family holdings among the largest in Venetian Dalmatia. Other noble families of Korčula were Kanavelić, Izmaeli, De Polo, Gabrijelić and Nikoničić