title: Gwar

text: The band's debut album, "Hell-O", a crossover thrash metal-punk rock album, was released in 1988 under Shimmy Disc. The band started touring in support of the album, with Steve Douglas leaving that same year, later to form the alternative band Log, and being replaced by current rhythm guitarist Michael Derks, who took over Douglas' alias as Balsac the Jaws of Death.


title: Gwar

text: However, the band's line-up underwent further changes before 1990. In 1988, the Slave Pit saw the joining of Bob Gorman, a young, new artist who would help with the art design and fabrication aspects of the band. One year later, in 1989, Rob Mobsy left the band and was replaced by Pete Luchter, who also quit to be replaced temporarily by Jim Thompson, who had been in the band prior to the release of "Hell-O". Thompson later quit and was replaced by Brad Roberts, who has since portrayed Jizmak Da Gusha.


title: Gwar

text: With Gwar's line-up somewhat solidified, the band would set up to record "Scumdogs of the Universe" released worldwide on producer Ivan Healy Purvis' label Master Records, a subsidiary of Blue Beat Records. The album met a moderately large mainstream success and would mark the start of a career under the Metal Blade Records record label. The band would tour extensively in support for this album, releasing the "Live from Antarctica" produced by Ivan Healy Purvis, VHS tape in July 1990, containing, among other things, the music video for the song "Sick of You". It was shortly after the video's release when the Slave Pit took in another new, young artist, Matt Maguire, to help out with costume fabrication, as well as illustrations for comics and related material.


title: Gwar

text: In August 1990, the birth of Michael Derks's daughter resulted in his taking a short break from the band. Barry 'D'live' Ward from the band Rich Kids on LSD filled in on guitar as Balsac during Gwar's 1991 European tour. On September 18, 1990, Brockie wore his "Cuttlefish of Cthulhu" codpiece during a show in Charlotte, North Carolina, resulting in Brockie's arrest and, ultimately, a one-year ban from the band performing in the state of North Carolina - the band would later highlight the absurdity of the case by pointing out that the presiding judge over the case was called Dick Boner. Upon returning home, Gwar filmed its first cameo in a mainstream film, "Mystery Date".


title: Gwar

text: "Scumdogs of the Universe" was originally released through the U.K. label Master before being picked up by Metal Blade in 1991. In the group's hunt for a larger label, they auditioned for Relativity Records, one of the larger independent heavy metal labels. The group failed their audition when they arrived in costume and Slymenstra Hymen broke a blood capsule from her codpiece onto one of the office chairs, simulating menstruation.


title: Gwar

text: The band suffered further line-up changes during this period, with Dewey Rowell leaving the band in 1991 and not being replaced until 1992 by Pete Lee, after the recording of "America Must Be Destroyed".The Charlotte, North Carolina incident from 1990 was the inspiration for Gwar's third album, "America Must Be Destroyed", released in 1992. The album was accompanied by the movie "Phallus in Wonderland", which documented the main concept and contained music videos for the album. "Phallus in Wonderland" was nominated for a Grammy Award in 1993. After recording for "This Toilet Earth" was completed, bassist Mike Bishop left the band. He was replaced by Casey Orr, from the band Rigor Mortis.


title: Gwar

text: "This Toilet Earth" was released in 1994, to moderate success. The album received additional attention due to controversy surrounding "B.D.F.", a song that graphically refers to subjects such as sodomy, necrophilia, pre-natal rape, pedophilia and mutilation. 1994 also saw the music videos for "Saddam a Go-Go" and "The Road Behind" being aired on "Beavis and Butt-head". This would also mark the beginning of the band straying from their trademark sound, as the album contained several experimental songs as opposed to the punk of "Hell-O" and thrash of "Scumdogs of the Universe".


title: Gwar

text: In 1995, Gwar released "Ragnarok", an album characterized by a unique sound, including the use of keyboards, something largely unseen before by the band, as well as a much larger use of secondary vocalists. The record is considered to have been largely unnoticed after the success of the previous three albums. Despite this, the band would record two videos for the album, "Surf of Syn" and "Meat Sandwich" as well as release "Rendezvous with Ragnarok" to support the album's plot through footage from the supporting tour. Later that year, the band also made a cameo appearance in the film "Empire Records".


title: Gwar

text: The band's first side project, X-Cops, would also come to life after the Ragnarok tour, releasing their only full-length album, "You Have the Right to Remain Silent...", the same year.


title: Gwar

text: Doom developer id Software hired Gwar to produce a showcase space at Microsoft's Judgement Day event for Halloween of 1995.


title: Gwar

text: The band's next record would come out in 1997 under the name "Carnival of Chaos", proving to be the epitome of this experimental period containing songs from many different genres, including the classic heavy metal, but also hard rock, country, and even jazz. Shortly after the release of "Carnival of Chaos", select members of the Gwar ensemble appeared on "The Jerry Springer Show" to discuss the growing trend of "shock rock" and their role as entertainers. Aside from their appearance on "The Joan Rivers Show", this guest appearance is still recognized as one of their most infamous appearances on national TV. In 1998, Gwar fought the ska band, The Aquabats!, during The Ska Parade.


title: Gwar

text: "Carnival of Chaos" would be the last album with Pete Lee on guitar, being replaced by Tim Harriss who had previously been in the band around 1986 and was featured as a guest guitarist on "America Must Be Destroyed". For the recording of "We Kill Everything" between late 1998 and early 1999, Michael Bishop would temporarily rejoin the band as the bassist during the absence of Casey Orr. The record, largely influenced by punk rock, is the band's least favorite album and thus its songs are rarely played live.


title: Gwar

text: Following this, co-founder, Hunter Jackson, left the group in 2000 to focus on personal projects. Danielle Stampe also left the band to focus on a personal project named "Girly Freakshow"; however, she rejoined the band temporarily for the Bitch Is Back tour in 2002.


title: Gwar

text: Due to the band's distaste for the previous album, Gwar's sound changed considerably for the next recording. With Tim Harriss gone, Zach Blair was hired to fill his spot as Flattus Maximus, Casey Orr also having returned to the band as Beefcake the Mighty for the recording of the band's first entirely thrash metal album in years: "Violence Has Arrived", released on November 6, 2001, the album being seen as a "comeback" of sorts and setting off changes that resulted in the current state of the band.


title: Gwar

text: In 2002 Zach Blair left Gwar to form the power-pop band Armstrong along with drummer Brad Roberts. The band released one album titled "Dick the Lionhearted". Since February 2007, Blair has been the guitarist for Rise Against.


title: Gwar

text: As the band focused on a heavier, more brutal sound near the end of this period, it would also result in the creation of another side project, the Dave Brockie Experience, a band created by frontman Dave Brockie along with rhythm guitarist Mike Derks and drummer Brad Roberts as a way of continuing the comedic sound found on albums like "We Kill Everything" while maintaining a more serious focus in releases by Gwar. They released their first LP on March 20, 2001, "Diarrhea of a Madman".


title: Gwar

text: In June 2004, Gwar left Metal Blade and signed with DRT Entertainment. The band left Metal Blade due to the label's perceived lack of faith in the band and the lack of album distribution beyond the US, along with the band's belief that they were funding "shitty bands on the label". Despite this, the band maintained they had no animosity to Brian Slagel or the label in general.


title: Gwar

text: Their first album for the label, "War Party", was released in October of that year"." The album met with a large underground success, as it followed the same path "Violence Has Arrived" did, but this time with a more serious and technical edge, partially thanks to the efforts of new lead guitarist Cory Smoot (Flattus Maximus) and bass guitarist Todd Evans (Beefcake the Mighty). Videos were released for "Bring Back the Bomb" and "War Party," and the band was invited to play on the Sounds of the Underground tour in 2005. That same year the band released "Live from Mt. Fuji", the band's first live album besides the then extremely rare "You're All Worthless and Weak", released in 2000 (and re-released in 2006) on Slave Pit Records.


title: Gwar

text: In 2004 Gwar teamed up with Grey DeLisle (as the voice of Grandma Stuffum) in the "" episode "Operation F. O. O. D. F. I. T. E."; the band was credited as Rawg and the songs "The Private Pain of Techno Destructo", "Morality Squad", and "Gor-Gor" were performed with new lyrics, pertaining to the episode, written for each song.


title: Gwar

text: Gwar began work on their next album, tentatively titled "Go to Hell!", in January 2006. That same month, Gwar opened a gallery show called "The Art of Gwar" at Art Space gallery in Richmond to display the many props, costumes, cartoons, paintings produced by The Slave Pit, Gwar's art and effects studio.


title: Gwar

text: On February 23, 2006, Gwar's official website announced Gwar's album, officially titled "Beyond Hell", for which, at the urging of DRT Entertainment, a cover version of Alice Cooper's "School's Out" was recorded and released. The music video was directed by David Brodsky on July 2, 2006. The part of the "school marm" has been mistakenly identified as Devin Townsend, the producer of the "Beyond Hell" CD. It is actually Scott Krahl, a long-time Gwar "slave" and inventor of Gor-Gor. "School's Out" was nominated for Best Video of 2006 on MTV2's "Headbanger's Ball".


title: Gwar

text: The "Blood Bath and Beyond" DVD was released on June 20, 2006, containing exclusive behind the scenes and vintage footage of the band.


title: Gwar

text: Gwar performed a special "half-time" show at the Sounds Of The Underground 2006 tour. Gwar went on to headline the following year's Sounds of the Underground Tour in 2007.


title: Gwar

text: Vocalist Oderus Urungus is also featured on the last Strapping Young Lad album The New Black as a guest vocalist on the song "Far Beyond Metal". Oderus' lines in the song are taken directly from the Gwar song "Maggots" ("now in the halls of the Necrolord..." etc.). Scott Krahl is in the "School's Out" video as a female teacher, with whom Oderus makes out before mounting "her" at the end of the video.


title: Gwar

text: "Beyond Hell" was released on August 29, 2006, with Gwar touring to support the album and being helped by the creation of new props for this tour, including several characters from "Beyond Hell"s plot, including Jitler and Jewcifer. Gwar was also present at the third annual Rock & Shock festival from October 13 to 15 as a part of this tour.


title: Gwar

text: In Spring 2008 Todd Evans left Gwar to focus efforts on his project Mobile Deathcamp. Shortly after Todd's departure, Casey Orr was confirmed to return as Beefcake the Mighty.


title: Gwar

text: In May 2009, Gwar re-signed with Metal Blade after DRT Entertainment closed down (with the band getting their master tapes from DRT), and the band and celebrated their 25th year of existence.


title: Gwar

text: Gwar's eleventh studio album, "Lust in Space", was released on August 18, 2009, They performed at the 2009 Gathering of the Juggalos and toured nationwide with Lamb of God and Job for a Cowboy. In 2009, Gwar celebrated their 25th year as a band.


title: Gwar

text: The band released a 2009 Christmas vinyl record consisting of a new song titled "Christmas Stripper Summer Weekend" and a live "Hell-O" medley.


title: Gwar

text: Oderus Urungus hosted the "Crack-a-Thon" in Brooklyn, New York at the MF Gallery in April 2010. A second Crack-A-Thon followed in 2011.


title: Gwar

text: On November 3, 2011, lead guitarist Cory Smoot, who had portrayed Flattus Maximus since 2002, was found dead by his fellow band members in the band's tour bus as they prepared to cross the border into Manitoba, Canada from North Dakota. The cause of death was "a coronary artery thrombosis brought about by his pre-existing coronary artery disease." On November 4, Dave Brockie officially announced that the character of Flattus Maximus would be retired out of respect to Smoot.


title: Gwar

text: The last single recorded with Smoot was released on December 22, 2011, and is a cover of the Dayglo Abortions song "Isn't This Disgusting". The single was made available on iTunes and appeared on the Dayglo Abortions tribute album in 2012.


title: Gwar

text: On April 3, 2012, a television sit-com created by horror filmmaker Adam Green and starring Brockie portraying Oderus Urungus titled "Holliston" debuted on the FEARnet cable television network. The series starred Oderus as series lead Green's imaginary alien friend who lives in his closet. Brockie toured and appeared with his castmates as Oderus at many live performances of "Holliston" across the United States in 2012 and 2013.


title: Gwar

text: Green appeared on stage with Gwar several times when the band had him introduce their encore performance. The full "Holliston" cast was "murdered" on stage and fed to both Gwar's world maggot and meat grinder at several US shows. A third season of "Holliston" was being scripted by Green when Brockie died of a heroin overdose in March 2014.


title: Gwar

text: Cannabis Corpse guitarist Brent Purgason took over the late Cory Smoot's role under the name Pustulus Maximus in late 2012, making his first appearance with the band in a video on The A.V. Club of the band playing a cover of Kansas' 1976 hit tune "Carry on My Wayward Son". In September 2013 Gwar's thirteenth studio album, titled "Battle Maximus," was released. Promotional activities for the record included a video of Gwar covering Billy Ocean's "Get Outta My Dreams, Get Into My Car" and The Who's "Baba O'Riley", and a one-off Funny Or Die animated cartoon produced by Myke Chilian and Gwar titled "The Animated Tales of Gwar".


title: Gwar

text: On March 23, 2014, Dave Brockie, age 50, was found dead by a roommate in his Richmond, Virginia, apartment. The cause of death was later confirmed to be a heroin overdose. Brockie's death left the band without any of its founding members.


title: Gwar

text: The surviving members of Gwar and the Slave Pit released a video statement to announce the creation of the David Brockie Foundation, a charity fund for the encouragement of future talent and the preservation of Brockie's body of work. Their first goal with the foundation was to construct a memorial monument to him in Richmond to provide a place of respect for the former frontman of Gwar. Former bassist Mike Bishop, the original Beefcake the Mighty, re-joined the band as vocalist for their first performance without Brockie at the fifth Gwar B-Q at Hadad's Lake. The performance was preceded by a public memorial service the day before, the singer's Oderus Urungus character was given a Viking funeral.


title: Gwar

text: Gwar played at the following month's Riot Fest in Chicago and went back on tour in December 2014, with new character Vulvatron, played by Kim Dylla . They also appeaered again in an A.V Club video, playing a cover of the Pet Shop Boys' "West End Girls" which transitioned into "People Who Died" by Jim Carroll—as a tribute to Cory Smoot, Dave Brockie and other friends of Gwar who have since passed on. Kim Dylla was released from the band at the end of 2014. In October 2016 Gwar released "The Blood of Gods," their first album without founding member and longtime vocalist Brockie.


title: Gwar

text: In January 2015, GwarBar (stylized as GWARbar) opened in the Jackson Ward neighborhood of Richmond, Virginia. Mike Derks and Travis Croxton, Richmond's "Restaurateur of the Year 2014," co-own the upscale dive bar. Derks, who also serves as executive chef, collaborated with head chef Jeremy Dutra to create the restaurant's menu. The band's website describes the bar as "a fantasy land of food and beverage, catering to everyone from local punk metal freaks, rock stars, businessmen, celebrity chefs and starving artists." On May 29, 2020, the restaurant opened its long-planned outdoor beer garden after being closed to indoor dining for two months as a result of the COVID-19 pandemic.


title: Gwar

text: In February 2019, Jamison Land left the band and Casey Orr later returned to fill the role of Beefcake once again. A remixed and remastered 30th anniversary edition of "Scumdogs of the Universe" was released the following year and on day of release the band broadcast an anniversary reunion concert where the album was performed in its entirety for the first time. Dubbed "Scumdogs XXX Live," it marked the first time that Gwar co-founder Hunter Jackson had directly worked with the band since his departure in 2000.


title: Gwar

text: "The Disc with No Name", a limited edition picture disc containing four acoustic renditions of previously released songs, was released in May 2021. The band embarked on a Scumdogs 30th anniversary tour, featuring co-founder Hunter Jackson, and released the "Scumdogs XXX Live" concert album. On June 3, 2022, Gwar released their fifteenth studio album, "The New Dark Ages", alongside a graphic novel, " Gwar In The Duoverse Of Absurdity", released by Z2 Comics.


title: Gwar

text: Since 2009 Gwar has hosted an annual festival in Richmond, VA called "Gwar-B-Q". The festival boasts of barbecue, rock-and-roll vendors, a haunted house of sorts (which "bohabs" can visit to be spewed and bled upon) and live music. Held at Hadad's Lake, a natural water park in Richmond, Gwar-B-Q has quickly grown into a destination event having hosted bands like Clutch, Down, Dead Earth Politics, Cancer Bats,


title: Gwar

text: and The Dickies. At the 2014 Gwar-B-Q, the first since Dave Brockie's death, the singer's Oderus Urungus character was given a Viking funeral, with his stage costume burned on a funeral pyre on Hadad's Lake.


title: Gwar

text: Despite various explanations that Gwar is an acronym for something (such as "God what an awful racket"), band members have consistently stated that the letters do not stand for anything. The official website of Slave Pit Inc. indicates that Gwar is a shortened version of "Gwaaarrrgghhlllgh", the name the band used originally when opening for Death Piggy.


title: Dhampir

text: In Balkans folklore, dhampirs (sometimes spelled "dhampyres", "dhamphirs", or "dhampyrs") are creatures that are the result of a union between a vampire and a mortal human. This union was usually between male vampires and female mortal humans, with stories of female vampires mating with male mortal humans being rare.


title: Dhampir

text: The word "dhampir" is an Albanian loanword borrowed from the Slavic original word "vampire". Vladimir Orel points out the similarity between Proto-Albanian *pīja and the Proto-Slavic cognate *pijǫ.


title: Dhampir

text: The word "dhampir" is associated with Balkan folklore, as described by T. P. Vukanović. In the rest of the region, terms such as Serbian "vampirović", "vampijerović", "vampirić" (thus, Bosnian "lampijerović", etc.) literally meaning "vampire's son", are used.


title: Dhampir

text: In other regions the child is named "Vampir" if a boy and "Vampirica" if a girl, or "Dhampir" if a boy and "Dhampirica" if a girl. In Bulgarian folklore, numerous terms such as "glog" (lit. "hawthorn"), "vampirdzhiya" ("vampire" + "nomen agentis" suffix), "vampirar" ("vampire" + "nomen agentis" suffix), "dzhadadzhiya" and "svetocher" are used to refer to vampire children and descendants, as well as to other specialized vampire hunters. Dhampiraj is also an Albanian surname.


title: Dhampir

text: In the Balkans it was believed that male vampires have a great desire for human women, so a vampire will return to have intercourse with his wife or with a woman he was attracted to in life. In one case, a Serbian widow tried to blame her pregnancy on her late husband, who had supposedly become a vampire, and there were cases of Serbian men pretending to be vampires in order to reach the women they desired. In Bulgarian folklore, vampires were sometimes said to deflower virgins as well. The sexual activity of the vampire seems to be a peculiarity of South Slavic vampire belief as opposed to other Slavs, although a similar motif also occurs in Belarusian legends.


title: Dhampir

text: Legends state that dhampirs were, for the most part, normal members of the community. But dhampirs, especially male, of paternal vampire descent could see invisible vampires and practice sorcery, often starting careers as vampire hunters, which would be practiced for generations from father to son. According to the legend, dhampyres have the powers of both humans and vampires: they can sense a supernatural creature within a specified distance, have acute sense of sight and hearing, have regenerating abilities, immortality, can walk in sunlight (which led to the adoption of the sobriquet "Daywalker"), eat like a human, can control animals, and can be used to destroy vampires. One unique distinction between vampires and dhampirs is that a dhampir’s blood is very acidic towards vampires and can melt any part or the complete body of a vampire.


title: Dhampir

text: Some traditions specify signs by which the children of a vampire can be recognized. Albanian legends state they have untamed dark or black hair and are very cunning or courageous in nature. They are not attracted to blood and can eat normally like other human beings. They also are not vulnerable to sunlight. In Bulgarian folklore, possible indications include being "very dirty", having a soft body, no nails or bones (the latter physical peculiarity is also ascribed to the vampire itself), and "a deep mark on the back, like a tail." In contrast, a pronounced nose was often a sign, as were larger than normal ears, teeth or eyes. According to J. Gordon Melton, from his book, "The Vampire Book: The Encyclopedia of the Undead", in some areas, a true dhampir possessed a "slippery, jelly-like body and lived only a short life—a belief... that vampires have no bones."


title: Enthalpy

text: Enthalpy , a property of a thermodynamic system, is the sum of the system's internal energy and the product of its pressure and volume. It is a state function used in many measurements in chemical, biological, and physical systems at a constant pressure, which is conveniently provided by the large ambient atmosphere. The pressure–volume term expresses the work required to establish the system's physical dimensions, i.e. to make room for it by displacing its surroundings. The pressure-volume term is very small for solids and liquids at common conditions, and fairly small for gases. Therefore, enthalpy is a stand-in for energy in chemical systems; bond, lattice, solvation and other "energies" in chemistry are actually enthalpy differences. As a state function, enthalpy depends only on the final configuration of internal energy, pressure, and volume, not on the path taken to achieve it.


title: Enthalpy

text: In the International System of Units (SI), the unit of measurement for enthalpy is the joule. Other historical conventional units still in use include the calorie and the British thermal unit (BTU).


title: Enthalpy

text: The total enthalpy of a system cannot be measured directly because the internal energy contains components that are unknown, not easily accessible, or are not of interest in thermodynamics. In practice, a change in enthalpy is the preferred expression for measurements at constant pressure because it simplifies the description of energy transfer. When transfer of matter into or out of the system is also prevented and no electrical or shaft work is done, at constant pressure the enthalpy change equals the energy exchanged with the environment by heat.


title: Enthalpy

text: In chemistry, the standard enthalpy of reaction is the enthalpy change when reactants in their standard states (; usually ) change to products in their standard states. This quantity is the standard heat of reaction at constant pressure and temperature, but it can be measured by calorimetric methods even if the temperature does vary during the measurement, provided that the initial and final pressure and temperature correspond to the standard state. The value does not depend on the path from initial to final state because enthalpy is a state function.


title: Enthalpy

text: Enthalpies of chemical substances are usually listed for pressure as a standard state. Enthalpies and enthalpy changes for reactions vary as a function of temperature, but tables generally list the standard heats of formation of substances at . For endothermic (heat-absorbing) processes, the change is a positive value; for exothermic (heat-releasing) processes it is negative.


title: Enthalpy

text: The enthalpy of an ideal gas is independent of its pressure or volume, and depends only on its temperature, which correlates to its thermal energy. Real gases at common temperatures and pressures often closely approximate this behavior, which simplifies practical thermodynamic design and analysis.


title: Enthalpy

text: The enthalpy of a thermodynamic system is defined as the sum of its internal energy and the product of its pressure and volume:


title: Enthalpy

text: where is the internal energy, is pressure, and is the volume of the system; is sometimes referred to as the pressure energy .


title: Enthalpy

text: Enthalpy is an extensive property; it is proportional to the size of the system (for homogeneous systems). As intensive properties, the specific enthalpy is referenced to a unit of mass of the system, and the molar enthalpy , where is the number of moles. For inhomogeneous systems the enthalpy is the sum of the enthalpies of the component subsystems:


title: Enthalpy

text: A closed system may lie in thermodynamic equilibrium in a static gravitational field, so that its pressure varies continuously with altitude, while, because of the equilibrium requirement, its temperature is invariant with altitude. (Correspondingly, the system's gravitational potential energy density also varies with altitude.) Then the enthalpy summation becomes an integral:


title: Enthalpy

text: The enthalpy of a closed homogeneous system is its energy function , with its entropy and its pressure as natural state variables which provide a differential relation for formula_3 of the simplest form, derived as follows. We start from the first law of thermodynamics for closed systems for an infinitesimal process:


title: Enthalpy

text: In a homogeneous system in which only reversible processes or pure heat transfer are considered, the second law of thermodynamics gives , with the absolute temperature and the infinitesimal change in entropy of the system. Furthermore, if only work is done, . As a result,


title: Enthalpy

text: and the coefficients of the natural variable differentials formula_9 and formula_10 are just the single variables formula_11 and formula_12.


title: Enthalpy

text: The above expression of in terms of entropy and pressure may be unfamiliar to some readers. There are also expressions in terms of more directly measurable variables such as temperature and pressure:


title: Enthalpy

text: With this expression one can, in principle, determine the enthalpy if and are known as functions of and . However the expression is more complicated than formula_15 because T is not a natural variable for the enthalpy H.


title: Enthalpy

text: At constant pressure, formula_16 so that formula_17 For an ideal gas, formula_3 reduces to this form even if the process involves a pressure change, because .


title: Enthalpy

text: In a more general form, the first law describes the internal energy with additional terms involving the chemical potential and the number of particles of various types. The differential statement for then becomes


title: Enthalpy

text: where is the chemical potential per particle for an -type particle, and is the number of such particles. The last term can also be written as (with the number of moles of component added to the system and, in this case, the molar chemical potential) or as (with the mass of component added to the system and, in this case, the specific chemical potential).


title: Enthalpy

text: The enthalpy, , expresses the thermodynamics of a system in the "energy representation". As a function of state, its arguments include both one intensive and several extensive state variables. The state variables , , and are said to be the "natural state variables" in this representation. They are suitable for describing processes in which they are determined by factors in the surroundings. For example, when a virtual parcel of atmospheric air moves to a different altitude, the pressure surrounding it changes, and the process is often so rapid that there is too little time for heat transfer. This is the basis of the so-called adiabatic approximation that is used in meteorology.


title: Enthalpy

text: Conjugate with the enthalpy, with these arguments, the other characteristic function of state of a thermodynamic system is its entropy, as a function, , of the same list of variables of state, except that the entropy, , is replaced in the list by the enthalpy, . It expresses the "entropy representation". The state variables , , and are said to be the "natural state variables" in this representation. They are suitable for describing processes in which they are experimentally controlled. For example, and can be controlled by allowing heat transfer, and by varying only the external pressure on the piston that sets the volume of the system.


title: Enthalpy

text: The term is the energy of the system, and the term can be interpreted as the work that would be required to "make room" for the system if the pressure of the environment remained constant. When a system, for example, moles of a gas of volume at pressure and temperature , is created or brought to its present state from absolute zero, energy must be supplied equal to its internal energy plus , where is the work done in pushing against the ambient (atmospheric) pressure.


title: Enthalpy

text: In physics and statistical mechanics it may be more interesting to study the internal properties of a constant-volume system and therefore the internal energy is used. In chemistry, experiments are often conducted at constant atmospheric pressure, and the pressure–volume work represents a small, well-defined energy exchange with the atmosphere, so that is the appropriate expression for the heat of reaction. For a heat engine, the change in its enthalpy after a full cycle is equal to zero, since the final and initial state are equal.


title: Enthalpy

text: In order to discuss the relation between the enthalpy increase and heat supply, we return to the first law for closed systems, with the physics sign convention: , where the heat is supplied by conduction, radiation, Joule heating. We apply it to the special case with a constant pressure at the surface. In this case the work is given by (where is the pressure at the surface, is the increase of the volume of the system). Cases of long range electromagnetic interaction require further state variables in their formulation, and are not considered here. In this case the first law reads:


title: Enthalpy

text: If the system is under constant pressure, and consequently, the increase in enthalpy of the system is equal to the heat added:


title: Enthalpy

text: In thermodynamics, one can calculate enthalpy by determining the requirements for creating a system from "nothingness"; the mechanical work required, , differs based upon the conditions that obtain during the creation of the thermodynamic system.


title: Enthalpy

text: Energy must be supplied to remove particles from the surroundings to make space for the creation of the system, assuming that the pressure remains constant; this is the term. The supplied energy must also provide the change in internal energy, , which includes activation energies, ionization energies, mixing energies, vaporization energies, chemical bond energies, and so forth. Together, these constitute the change in the enthalpy . For systems at constant pressure, with no external work done other than the work, the change in enthalpy is the heat received by the system.


title: Enthalpy

text: For a simple system with a constant number of particles at constant pressure, the difference in enthalpy is the maximum amount of thermal energy derivable from an isobaric thermodynamic process.


title: Enthalpy

text: The total enthalpy of a system cannot be measured directly; the "enthalpy change" of a system is measured instead. Enthalpy change is defined by the following equation:


title: Enthalpy

text: For an exothermic reaction at constant pressure, the system's change in enthalpy, , is negative due to the products of the reaction having a smaller enthalpy than the reactants, and equals the heat released in the reaction if no electrical or shaft work is done. In other words, the overall decrease in enthalpy is achieved by the generation of heat. Conversely, for a constant-pressure endothermic reaction, is positive and equal to the heat "absorbed" in the reaction.


title: Enthalpy

text: From the definition of enthalpy as , the enthalpy change at constant pressure is . However for most chemical reactions, the work term is much smaller than the internal energy change , which is approximately equal to . As an example, for the combustion of carbon monoxide 2 CO(g) + O(g) → 2 CO(g), and . Since the differences are so small, reaction enthalpies are often described as reaction energies and analyzed in terms of bond energies.


title: Enthalpy

text: The specific enthalpy of a uniform system is defined as where is the mass of the system. The SI unit for specific enthalpy is joule per kilogram. It can be expressed in other specific quantities by , where is the specific internal energy, is the pressure, and is specific volume, which is equal to , where is the density.


title: Enthalpy

text: An enthalpy change describes the change in enthalpy observed in the constituents of a thermodynamic system when undergoing a transformation or chemical reaction. It is the difference between the enthalpy after the process has completed, i.e. the enthalpy of the products assuming that the reaction goes to completion, and the initial enthalpy of the system, namely the reactants. These processes are specified solely by their initial and final states, so that the enthalpy change for the reverse is the negative of that for the forward process.


title: Enthalpy

text: A common standard enthalpy change is the enthalpy of formation, which has been determined for a large number of substances. Enthalpy changes are routinely measured and compiled in chemical and physical reference works, such as the CRC Handbook of Chemistry and Physics. The following is a selection of enthalpy changes commonly recognized in thermodynamics.


title: Enthalpy

text: When used in these recognized terms the qualifier "change" is usually dropped and the property is simply termed "enthalpy of 'process"'. Since these properties are often used as reference values it is very common to quote them for a standardized set of environmental parameters, or standard conditions, including:


title: Enthalpy

text: For such standardized values the name of the enthalpy is commonly prefixed with the term "standard", e.g. "standard enthalpy of formation".


title: Enthalpy

text: In thermodynamic open systems, mass (of substances) may flow in and out of the system boundaries. The first law of thermodynamics for open systems states: The increase in the internal energy of a system is equal to the amount of energy added to the system by mass flowing in and by heating, minus the amount lost by mass flowing out and in the form of work done by the system:


title: Enthalpy

text: where is the average internal energy entering the system, and is the average internal energy leaving the system.


title: Enthalpy

text: The region of space enclosed by the boundaries of the open system is usually called a control volume, and it may or may not correspond to physical walls. If we choose the shape of the control volume such that all flow in or out occurs perpendicular to its surface, then the flow of mass into the system performs work as if it were a piston of fluid pushing mass into the system, and the system performs work on the flow of mass out as if it were driving a piston of fluid. There are then two types of work performed: "flow work" described above, which is performed on the fluid (this is also often called " work"), and "shaft work", which may be performed on some mechanical device such as a turbine or pump.


title: Enthalpy

text: The definition of enthalpy, , permits us to use this thermodynamic potential to account for both internal energy and work in fluids for open systems:


title: Enthalpy

text: If we allow also the system boundary to move (e.g. due to moving pistons), we get a rather general form of the first law for open systems. In terms of time derivatives it reads:


title: Enthalpy

text: with sums over the various places where heat is supplied, mass flows into the system, and boundaries are moving. The terms represent enthalpy flows, which can be written as


title: Enthalpy

text: with the mass flow and the molar flow at position respectively. The term represents the rate of change of the system volume at position that results in power done by the system. The parameter represents all other forms of power done by the system such as shaft power, but it can also be, say, electric power produced by an electrical power plant.


title: Enthalpy

text: Note that the previous expression holds true only if the kinetic energy flow rate is conserved between system inlet and outlet. Otherwise, it has to be included in the enthalpy balance. During steady-state operation of a device ("see turbine, pump, and engine"), the average may be set equal to zero. This yields a useful expression for the average power generation for these devices in the absence of chemical reactions:


title: Enthalpy

text: where the angle brackets denote time averages. The technical importance of the enthalpy is directly related to its presence in the first law for open systems, as formulated above.


title: Enthalpy

text: The enthalpy values of important substances can be obtained using commercial software. Practically all relevant material properties can be obtained either in tabular or in graphical form. There are many types of diagrams, such as diagrams, which give the specific enthalpy as function of temperature for various pressures, and diagrams, which give as function of for various . One of the most common diagrams is the temperature–specific entropy diagram ( diagram). It gives the melting curve and saturated liquid and vapor values together with isobars and isenthalps. These diagrams are powerful tools in the hands of the thermal engineer.


title: Enthalpy

text: One of the simple applications of the concept of enthalpy is the so-called throttling process, also known as Joule–Thomson expansion. It concerns a steady adiabatic flow of a fluid through a flow resistance (valve, porous plug, or any other type of flow resistance) as shown in the figure. This process is very important, since it is at the heart of domestic refrigerators, where it is responsible for the temperature drop between ambient temperature and the interior of the refrigerator. It is also the final stage in many types of liquefiers.


title: Enthalpy

text: For a steady state flow regime, the enthalpy of the system (dotted rectangle) has to be constant. Hence


title: Enthalpy

text: Since the mass flow is constant, the specific enthalpies at the two sides of the flow resistance are the same:


title: Enthalpy

text: that is, the enthalpy per unit mass does not change during the throttling. The consequences of this relation can be demonstrated using the diagram above.


title: Enthalpy

text: Point c is at 200 bar and room temperature (300 K). A Joule–Thomson expansion from 200 bar to 1 bar follows a curve of constant enthalpy of roughly 425 kJ/kg (not shown in the diagram) lying between the 400 and 450 kJ/kg isenthalps and ends in point d, which is at a temperature of about 270 K. Hence the expansion from 200 bar to 1 bar cools nitrogen from 300 K to 270 K. In the valve, there is a lot of friction, and a lot of entropy is produced, but still the final temperature is below the starting value.


title: Enthalpy

text: Point e is chosen so that it is on the saturated liquid line with = 100 kJ/kg. It corresponds roughly with = 13 bar and = 108 K. Throttling from this point to a pressure of 1 bar ends in the two-phase region (point f). This means that a mixture of gas and liquid leaves the throttling valve. Since the enthalpy is an extensive parameter, the enthalpy in f () is equal to the enthalpy in g () multiplied by the liquid fraction in f () plus the enthalpy in h () multiplied by the gas fraction in f . So


title: Enthalpy

text: With numbers: , so = 0.64. This means that the mass fraction of the liquid in the liquid–gas mixture that leaves the throttling valve is 64%.


title: Enthalpy

text: A power is applied e.g. as electrical power. If the compression is adiabatic, the gas temperature goes up. In the reversible case it would be at constant entropy, which corresponds with a vertical line in the diagram. For example, compressing nitrogen from 1 bar (point a) to 2 bar (point b) would result in a temperature increase from 300 K to 380 K. In order to let the compressed gas exit at ambient temperature , heat exchange, e.g. by cooling water, is necessary. In the ideal case the compression is isothermal. The average heat flow to the surroundings is . Since the system is in the steady state the first law gives


title: Enthalpy

text: The minimal power needed for the compression is realized if the compression is reversible. In that case the second law of thermodynamics for open systems gives


title: Enthalpy

text: For example, compressing 1 kg of nitrogen from 1 bar to 200 bar costs at least . With the data, obtained with the diagram, we find a value of 476 kJ/kg.


title: Enthalpy

text: The term "enthalpy" was coined relatively late in the history of thermodynamics, in the early 20th century. Energy was introduced in a modern sense by Thomas Young in 1802, while entropy was coined by Rudolf Clausius in 1865. "Energy" uses the root of the Greek word ("ergon"), meaning "work", to express the idea of capacity to perform work. "Entropy" uses the Greek word ("tropē") meaning "transformation" or "turning". "Enthalpy" uses the root of the Greek word ("thalpos") "warmth, heat".


title: Enthalpy

text: The term expresses the obsolete concept of "heat content", as refers to the amount of heat gained in a process at constant pressure only, but not in the general case when pressure is variable.


title: Enthalpy

text: Introduction of the concept of "heat content" is associated with Benoît Paul Émile Clapeyron and Rudolf Clausius (Clausius–Clapeyron relation, 1850).


title: Enthalpy

text: The term "enthalpy" first appeared in print in 1909. It is attributed to Heike Kamerlingh Onnes, who most likely introduced it orally the year before, at the first meeting of the Institute of Refrigeration in Paris.


title: Enthalpy

text: It gained currency only in the 1920s, notably with the "Mollier Steam Tables and Diagrams", published in 1927.


title: Enthalpy

text: The definition of as strictly limited to enthalpy or "heat content at constant pressure" was formally proposed by Alfred W. Porter in 1922.


title: E. M. Forster

text: Edward Morgan Forster (1 January 1879 – 7 June 1970) was an English author, best known for his novels, particularly "A Room with a View" (1908), "Howards End" (1910), and "A Passage to India" (1924). He also wrote numerous short stories, essays, speeches and broadcasts, as well a limited number of biographies and some pageant plays. He also co-authored the opera "Billy Budd" (1951). Today, he is considered one of the most successful of the Edwardian era English novelists.


title: E. M. Forster

text: Born into a comfortable middle-class family, Forster was an only child. His father died before he reached the age of two, and thereafter he was raised by his mother and a variety of other female relatives. After attending Tonbridge School he studied history and classics at King's College, Cambridge, where he met fellow future writers such as Lytton Strachey and Leonard Woolf. He then travelled throughout Europe before publishing his first novel, "Where Angels Fear to Tread" in 1905.


title: E. M. Forster

text: Many of his novels examine class difference and hypocrisy. He was nominated for the Nobel Prize in Literature in 20 separate years.


title: E. M. Forster

text: Forster, born at 6 Melcombe Place, Dorset Square, London NW1, which no longer stands, was the only child of the Anglo-Irish Alice Clara "Lily" (née Whichelo) and a Welsh architect, Edward Morgan Llewellyn Forster. He was registered as Henry Morgan Forster, but accidentally baptised Edward Morgan Forster. His father died of tuberculosis on 30 October 1880 before Morgan's second birthday. In 1883, he and his mother moved to Rooks Nest, near Stevenage, Hertfordshire until 1893. This was to serve as a model for the house Howards End in his novel of that name. It is listed Grade I for historic interest and literary associations. Forster had fond memories of his childhood at Rooks Nest.


title: E. M. Forster

text: Among Forster's ancestors were members of the Clapham Sect, a social reform group in the Church of England. Forster inherited £8,000 () in trust from his paternal great-aunt Marianne Thornton (daughter of the abolitionist Henry Thornton), who died on 5 November 1887. This was enough to live on and enabled him to become a writer. He attended as a day boy Tonbridge School in Kent, where the school theatre has been named in his honour, although he is known to have been unhappy there.


title: E. M. Forster

text: At King's College, Cambridge in 1897–1901, he became a member of a discussion society known as the Apostles (formally the Cambridge "Conversazione" Society). They met in secret to discuss their work on philosophical and moral questions. Many of its members went on to constitute what came to be known as the Bloomsbury Group, of which Forster was a member in the 1910s and 1920s. There is a famous recreation of Forster's Cambridge at the beginning of "The Longest Journey". The Schlegel sisters of "Howards End" are based to some degree on Vanessa and Virginia Stephen. Forster graduated with a BA with second-class honours in both classics and history.


title: E. M. Forster

text: In 1904, Forster travelled in Greece and Italy out of interest in their classical heritage. He then sought a post in Germany, to learn the language, and spent several months in the summer of 1905 in Nassenheide, Pomerania, (now the Polish village of Rzędziny) as a tutor to the children of the writer Elizabeth von Arnim. He wrote a short memoir of this experience, which was one of the happiest times in his life.


title: E. M. Forster

text: In 1906 Forster fell in love with Syed Ross Masood, a 17-year-old Indian future Oxford student he tutored in Latin. Masood had a more romantic, poetic view of friendship, confusing Forster with avowals of love.


title: E. M. Forster

text: After leaving university, Forster travelled in Europe with his mother. They then moved to Weybridge, Surrey, where he wrote all six of his novels.


title: E. M. Forster

text: In 1914, he visited Egypt, Germany and India with the classicist Goldsworthy Lowes Dickinson, by which time he had written all but one of his novels. As a conscientious objector in the First World War, Forster served as a Chief Searcher (for missing servicemen) for the British Red Cross in Alexandria, Egypt. Though conscious of his repressed desires, it was only then, while stationed in Egypt, that he "lost his R [respectability]" to a wounded soldier in 1917.


title: E. M. Forster

text: Forster spent a second spell in India in the early 1920s as private secretary to Tukojirao III, Maharajah of Dewas. "The Hill of Devi" is his non-fictional account of this period. After returning to London from India, he completed the last novel of his to be published in his lifetime, "A Passage to India" (1924), for which he won the James Tait Black Memorial Prize for fiction. He also edited the letters of Eliza Fay (1756–1816) from India, in an edition first published in 1925. In 2012, Tim Leggatt, who knew Forster for his last 15 years, wrote a memoir based on unpublished correspondence with him over those years.


title: E. M. Forster

text: Forster was awarded a Benson Medal in 1937. In the 1930s and 1940s Forster became a notable broadcaster on BBC Radio, and while George Orwell was the BBC India Section talks producer from 1941 to 1943, he commissioned from Forster a weekly book review. Forster became publicly associated with the British Humanist Association. In addition to his broadcasting, he advocated individual liberty and penal reform and opposed censorship by writing articles, sitting on committees and signing letters.


title: E. M. Forster

text: Forster was open about his homosexuality to close friends, but not to the public. He never married, but had a number of male lovers during his adult life. He developed long-term relations with Bob Buckingham (1904–1975), a married policeman. Forster included Buckingham and his wife May in his circle, which included J. R. Ackerley, a writer and literary editor of "The Listener," the psychologist W. J. H. Sprott, and for a time, the composer Benjamin Britten. Other writers with whom he associated included Christopher Isherwood, the poet Siegfried Sassoon, and the Belfast-based novelist Forrest Reid. He was a close friend of the socialist poet and philosopher Edward Carpenter. A visit to Carpenter and his younger lover George Merrill in 1913 inspired Forster's novel "Maurice", which is partly based on them.


title: E. M. Forster

text: In 1960, Forster began a relationship with the Bulgarian émigré Mattei Radev, a picture framer and art collector who moved in Bloomsbury group circles. He was Forster's junior by 46 years. They met at Long Crichel House, a Georgian rectory in Long Crichel, Dorset, a country retreat shared by Edward Sackville-West and the gallery-owner and artist Eardley Knollys.


title: E. M. Forster

text: From 1925 until his mother's death at age 90 in March 1945, Forster lived with her at the house West Hackhurst in the village of Abinger Hammer, Surrey, finally leaving in September 1946. His London base was 26 Brunswick Square from 1930 to 1939, after which he rented 9 Arlington Park Mansions in Chiswick until at least 1961. After a fall in April 1961, he spent his final years in Cambridge at King's College.


title: E. M. Forster

text: Forster was elected an honorary fellow of King's College in January 1946, and lived for the most part in the college, doing relatively little. In April 1947 he arrived in America for a three-month nationwide tour of public readings and sightseeing, returning to the East Coast in June. He declined a knighthood in 1949 and was made a Companion of Honour in 1953. At age 82, he wrote his last short story, "Little Imber", a science fiction tale. According to his friend Richard Marquand, Forster was critical of American foreign policy in his latter years, which was one reason he refused offers to adapt his novels for the screen, as Forster felt such productions would involve American financing.


title: E. M. Forster

text: At 85 he went on a pilgrimage to the Wiltshire countryside that had inspired his favourite novel "The Longest Journey", escorted by William Golding. In 1961 he was one of the first five authors named as a Companion of Literature by the Royal Society of Literature. In 1969 he was made a member of the Order of Merit. Forster died of a stroke on 7 June 1970 at the age of 91, at the Buckinghams' home in Coventry, Warwickshire. His ashes, mingled with those of Buckingham, were later scattered in the rose garden of Coventry's crematorium, near Warwick University.


title: E. M. Forster

text: Forster had five novels published in his lifetime. Although "Maurice" was published shortly after his death, it had been written nearly sixty years earlier. He never finished a seventh novel, "Arctic Summer".


title: E. M. Forster

text: His first novel, "Where Angels Fear to Tread" (1905), tells of Lilia, a young English widow who falls in love with an Italian, and of the efforts of her bourgeois relatives to get her back from Monteriano (based on San Gimignano). Philip Herriton's mission to retrieve her from Italy has features in common with that of Lambert Strether in Henry James's "The Ambassadors." Forster discussed that work ironically and somewhat disapprovingly in his book "Aspects of the Novel" (1927). The novel was adapted as a 1991 film directed by Charles Sturridge.


title: E. M. Forster

text: Next, Forster published "The Longest Journey" (1907), an inverted "Bildungsroman" following the lame Rickie Elliott from Cambridge to a career as a struggling writer and then a post as a schoolmaster, married to an unappealing Agnes Pembroke. In a series of scenes on the Wiltshire hills, which introduce Rickie's wild half-brother Stephen Wonham, Forster attempts a kind of sublime related to those of Thomas Hardy and D. H. Lawrence.


title: E. M. Forster

text: Forster's third novel, "A Room with a View" (1908), is his lightest and most optimistic. It was started in 1901, before any of his others, initially under the title "Lucy". It explores young Lucy Honeychurch's trip to Italy with a cousin, and the choice she must make between the free-thinking George Emerson and the repressed aesthete Cecil Vyse. George's father Mr Emerson quotes thinkers who influenced Forster, including Samuel Butler. It was adapted as a film of the same name in 1985 by the Merchant Ivory team, starring Helena Bonham Carter and Daniel Day-Lewis, and as a televised adaptation of the same name in 2007 by Andrew Davies.


title: E. M. Forster

text: "Where Angels Fear to Tread" and "A Room with a View" can be seen as Forster's Italian novels. Both include references to the famous Baedeker guidebooks and concern narrow-minded middle-class English tourists abroad. The books share themes with his short stories collected in "The Celestial Omnibus" and "The Eternal Moment".


title: E. M. Forster

text: "Howards End" (1910) is an ambitious "condition-of-England" novel about various groups among the Edwardian middle classes, represented by the Schlegels (bohemian intellectuals), the Wilcoxes (thoughtless plutocrats) and the Basts (struggling lower-middle-class aspirants). "Howards End" was adapted as a film in 1992 by the Merchant-Ivory team, starring Vanessa Redgrave, Emma Thompson, Anthony Hopkins, and Helena Bonham-Carter. Emma Thompson won the Academy Award for Best Actress for her performance as Margaret Schlegel. It was also adapted as a miniseries in 2017. An opera libretto "Howards End, America" was created in 2016 by Claudia Stevens.


title: E. M. Forster

text: Forster's greatest success, "A Passage to India" (1924), takes as its subject the relations between East and West, seen through the lens of India in the later days of the British Raj. Forster connects personal relations with the politics of colonialism through the story of the Englishwoman Adela Quested, the Indian Dr. Aziz, and the question of what did or did not happen between them in the Marabar Caves. Forster makes special mention of the author Ahmed Ali and his "Twilight in Delhi" in a preface to its Everyman's Library Edition. "A Passage to India" was adapted as a play in 1960, directed by Frank Hauser, and as a film in 1984, directed by David Lean.


title: E. M. Forster

text: "Maurice" (1971), published posthumously, is a homosexual love story that also returns to matters familiar from Forster's first three novels, such as the suburbs of London in the English home counties, the experience of attending Cambridge, and the wild landscape of Wiltshire. The novel was controversial, given that Forster's homosexuality had not been known or widely acknowledged. Today's critics continue to argue over the extent to which Forster's sexuality and personal activities influenced his writing. "Maurice" was adapted as a film in 1987 by the Merchant Ivory team.


title: E. M. Forster

text: Early in his career, Forster attempted a historical novel about the Byzantine scholar Gemistus Pletho and the Italian condottiero Sigismondo de Malatesta, but was dissatisfied with the result and never published it, though he kept the manuscript and later showed it to Naomi Mitchison.


title: E. M. Forster

text: Forster's first novel, "Where Angels Fear to Tread", was described by reviewers as "astonishing" and "brilliantly original". "The Manchester Guardian" (forerunner of "The Guardian") noted "a persistent vein of cynicism which is apt to repel," though "the cynicism is not deep-seated." The novel is labelled "a sordid comedy culminating, unexpectedly and with a real dramatic force, in a grotesque tragedy." Lionel Trilling remarked on this first novel as "a whole and mature work dominated by a fresh and commanding intelligence".


title: E. M. Forster

text: Subsequent books were similarly received on publication. "The Manchester Guardian" commented on "Howards End", describing it as "a novel of high quality written with what appears to be a feminine brilliance of perception... witty and penetrating." An essay by David Cecil in "Poets and Storytellers" (1949) describes Forster as "pulsing with intelligence and sensibility", but primarily concerned with an original moral vision: "He tells a story as well as anyone who ever lived".


title: E. M. Forster

text: US interest in Forster and appreciation for him were spurred by Lionel Trilling's "E. M. Forster: A Study", which called him "the only living novelist who can be read again and again and who, after each reading, gives me what few writers can give us after our first days of novel-reading, the sensation of having learned something."


title: E. M. Forster

text: Criticism of his works has included comment on unlikely pairings of characters who marry or get engaged, and the lack of realistic depiction of sexual attraction.


title: E. M. Forster

text: Forster was President of the Cambridge Humanists from 1959 until his death and a member of the Advisory Council of the British Humanist Association from 1963 until his death. His views as a humanist are at the heart of his work, which often depicts the pursuit of personal connections despite the restrictions of contemporary society. His humanist attitude is expressed in the 1938 essay "What I Believe" (reprinted with two other humanist essays – and an introduction and notes by Nicolas Walter – as "What I Believe, and other essays" by the secular humanist publishers G. W. Foote & Co. in 1999). When Forster's cousin, Philip Whichelo, donated a portrait of Forster to the Gay and Lesbian Humanist Association (GLHA), Jim Herrick, the founder, quoted Forster's words: "The humanist has four leading characteristics – curiosity, a free mind, belief in good taste, and belief in the human race."


title: E. M. Forster

text: Forster's two best-known works, "A Passage to India" and "Howards End", explore the irreconcilability of class differences. "A Room with a View" also shows how questions of propriety and class can make human connection difficult. The novel is his most widely read and accessible work, remaining popular long after its original publication. His posthumous novel "Maurice" explores the possibility of class reconciliation as one facet of a homosexual relationship.


title: E. M. Forster

text: Sexuality is another key theme in Forster's works. Some critics have argued that a general shift from heterosexual to homosexual love can be observed through the course of his writing career. The foreword to "Maurice" describes his struggle with his homosexuality, while he explored similar issues in several volumes of short stories. Forster's explicitly homosexual writings, the novel "Maurice" and the short story collection "The Life to Come," were published shortly after his death.


title: E. M. Forster

text: Forster is noted for his use of symbolism as a technique in his novels, and he has been criticised (as by his friend Roger Fry) for his attachment to mysticism. One example of his symbolism is the wych elm tree in "Howards End." The characters of Mrs Wilcox in that novel and Mrs Moore in "A Passage to India" have a mystical link with the past, and a striking ability to connect with people from beyond their own circles. Henry James, E. M. Forster and Somerset Maugham were the earliest fiction writers to portray characters from diverse countries – France, Germany, Italy and India. Their work explores cultural conflict, but arguably the motifs of humanism and cosmopolitanism are dominant. In a way this is anticipation of the concept of human beings shedding national identities and becoming more and more liberal and tolerant.


title: Dark energy

text: In physical cosmology and astronomy, dark energy is an unknown form of energy that affects the universe on the largest scales. The first observational evidence for its existence came from measurements of supernovas, which showed that the universe does not expand at a constant rate; rather, the universe's expansion is accelerating. Understanding the universe's evolution requires knowledge of its starting conditions and composition. Before these observations, scientists thought that all forms of matter and energy in the universe would only cause the expansion to slow down over time. Measurements of the cosmic microwave background (CMB) suggest the universe began in a hot Big Bang, from which general relativity explains its evolution and the subsequent large-scale motion. Without introducing a new form of energy, there was no way to explain how scientists could measure an accelerating universe. Since the 1990s, dark energy has been the most accepted premise to account for the accelerated expansion. As of 2021, there are active areas of cosmology research to understand the fundamental nature of dark energy. Assuming that the lambda-CDM model of cosmology is correct, as of 2013, the best current measurements indicate that dark energy contributes 68% of the total energy in the present-day observable universe. The mass–energy of dark matter and ordinary (baryonic) matter contributes 26% and 5%, respectively, and other components such as neutrinos and photons contribute a very small amount. Dark energy's density is very low - 6×10 J/m (~formula_1 g/cm), much less than the density of ordinary matter or dark matter within galaxies. However, it dominates the universe's mass–energy content because it is uniform across space.


title: Dark energy

text: Two proposed forms of dark energy are the cosmological constant (representing a constant energy density filling space homogeneously) and scalar fields (dynamic quantities having energy densities that vary in time and space) such as quintessence or moduli. Contributions from scalar fields that are constant in space are usually also included in the cosmological constant. The cosmological constant can be formulated to be equivalent to the zero-point radiation of space, i.e., the vacuum energy. However, scalar fields that change in space can be difficult to distinguish from a cosmological constant because the change may be prolonged.


title: Dark energy

text: Due to the toy model nature of concordance cosmology, some experts believe that a more accurate general relativistic treatment of the structures on all scales in the real universe may do away with the need to invoke dark energy. Inhomogeneous cosmologies, which attempt to account for the back-reaction of structure formation on the metric, generally do not acknowledge any dark energy contribution to the universe's energy density.


title: Dark energy

text: The "cosmological constant" is a constant term that can be added to Einstein field equations of general relativity. If considered as a "source term" in the field equation, it can be viewed as equivalent to the mass of empty space (which conceptually could be either positive or negative), or "vacuum energy".


title: Dark energy

text: The cosmological constant was first proposed by Einstein as a mechanism to obtain a solution to the gravitational field equation that would lead to a static universe, effectively using dark energy to balance gravity. Einstein gave the cosmological constant the symbol Λ (capital lambda). Einstein stated that the cosmological constant required that 'empty space takes the role of gravitating negative masses which are distributed all over the interstellar space'.


title: Dark energy

text: The mechanism was an example of fine-tuning, and it was later realized that Einstein's static universe would not be stable: local inhomogeneities would ultimately lead to either the runaway expansion or contraction of the universe. The equilibrium is unstable: if the universe expands slightly, then the expansion releases vacuum energy, which causes yet more expansion. Likewise, a universe which contracts slightly will continue contracting. According to Einstein, "empty space" can possess its own energy. Because this energy is a property of space itself, it would not be diluted as space expands. As more space comes into existence, more of this energy-of-space would appear. These sorts of disturbances are inevitable, due to the uneven distribution of matter throughout the universe. Further, observations made by Edwin Hubble in 1929 showed that the universe appears to be expanding and not static at all. Einstein reportedly referred to his failure to predict the idea of a dynamic universe, in contrast to a static universe, as his greatest blunder.


title: Dark energy

text: Alan Guth and Alexei Starobinsky proposed in 1980 that a negative pressure field, similar in concept to dark energy, could drive cosmic inflation in the very early universe. Inflation postulates that some repulsive force, qualitatively similar to dark energy, resulted in an enormous and exponential expansion of the universe slightly after the Big Bang. Such expansion is an essential feature of most current models of the Big Bang. However, inflation must have occurred at a much higher energy density than the dark energy we observe today and is thought to have completely ended when the universe was just a fraction of a second old. It is unclear what relation, if any, exists between dark energy and inflation. Even after inflationary models became accepted, the cosmological constant was thought to be irrelevant to the current universe.


title: Dark energy

text: Nearly all inflation models predict that the total (matter+energy) density of the universe should be very close to the critical density. During the 1980s, most cosmological research focused on models with critical density in matter only, usually 95% cold dark matter (CDM) and 5% ordinary matter (baryons). These models were found to be successful at forming realistic galaxies and clusters, but some problems appeared in the late 1980s: in particular, the model required a value for the Hubble constant lower than preferred by observations, and the model under-predicted observations of large-scale galaxy clustering. These difficulties became stronger after the discovery of anisotropy in the by the COBE spacecraft in 1992, and several modified CDM models came under active study through the mid-1990s: these included the Lambda-CDM model and a mixed cold/hot dark matter model. The first direct evidence for dark energy came from supernova observations in 1998 of accelerated expansion in Riess "et al." and in Perlmutter "et al.", and the Lambda-CDM model then became the leading model. Soon after, dark energy was supported by independent observations: in 2000, the BOOMERanG and Maxima experiments observed the first acoustic peak in the CMB, showing that the total (matter+energy) density is close to 100% of critical density. Then in 2001, the 2dF Galaxy Redshift Survey gave strong evidence that the matter density is around 30% of critical. The large difference between these two supports a smooth component of dark energy making up the difference. Much more precise measurements from WMAP in 2003–2010 have continued to support the standard model and give more accurate measurements of the key parameters.


title: Dark energy

text: The term "dark energy", echoing Fritz Zwicky's "dark matter" from the 1930s, was coined by Michael Turner in 1998.


title: Dark energy

text: High-precision measurements of the expansion of the universe are required to understand how the expansion rate changes over time and space. In general relativity, the evolution of the expansion rate is estimated from the curvature of the universe and the cosmological equation of state (the relationship between temperature, pressure, and combined matter, energy, and vacuum energy density for any region of space). Measuring the equation of state for dark energy is one of the biggest efforts in observational cosmology today. Adding the cosmological constant to cosmology's standard FLRW metric leads to the Lambda-CDM model, which has been referred to as the ""standard model of cosmology"" because of its precise agreement with observations.


title: Dark energy

text: As of 2013, the Lambda-CDM model is consistent with a series of increasingly rigorous cosmological observations, including the Planck spacecraft and the Supernova Legacy Survey. First results from the SNLS reveal that the average behavior (i.e., equation of state) of dark energy behaves like Einstein's cosmological constant to a precision of 10%. Recent results from the Hubble Space Telescope Higher-Z Team indicate that dark energy has been present for at least 9 billion years and during the period preceding cosmic acceleration.


title: Dark energy

text: The nature of dark energy is more hypothetical than that of dark matter, and many things about it remain in the realm of speculation. Dark energy is thought to be very homogeneous and not very dense, and is not known to interact through any of the fundamental forces other than gravity. Since it is quite rarefied and un-massive—roughly 10 kg/m—it is unlikely to be detectable in laboratory experiments. The reason dark energy can have such a profound effect on the universe, making up 68% of universal density in spite of being so dilute, is that it uniformly fills otherwise empty space.


title: Dark energy

text: The vacuum energy, that is, the particle-antiparticle pairs generated and mutually annihilated within a time frame in accord with Heisenberg's uncertainty principle in the energy-time formulation, has been often invoked as the main contribution to dark energy. The mass-energy equivalence postulated by general relativity implies that the vacuum energy should exert a gravitational force. Hence, the vacuum energy is expected to contribute to the cosmological constant, which in turn impinges on the accelerated expansion of the universe. However, the cosmological constant problem asserts that there is a huge disagreement between the observed values of vacuum energy density and the theoretical large value of zero-point energy obtained by quantum field theory. The cosmological constant problem remains unresolved.


title: Dark energy

text: Independently of its actual nature, dark energy would need to have a strong negative pressure to explain the observed acceleration of the expansion of the universe. According to general relativity, the pressure within a substance contributes to its gravitational attraction for other objects just as its mass density does. This happens because the physical quantity that causes matter to generate gravitational effects is the stress–energy tensor, which contains both the energy (or matter) density of a substance and its pressure. In the Friedmann–Lemaître–Robertson–Walker metric, it can be shown that a strong constant negative pressure ("i.e.," tension) in all the universe causes an acceleration in the expansion if the universe is already expanding, or a deceleration in contraction if the universe is already contracting. This accelerating expansion effect is sometimes labeled "gravitational repulsion".


title: Dark energy

text: In standard cosmology, there are three components of the universe: matter, radiation, and dark energy. Matter is anything whose energy density scales with the inverse cube of the scale factor, i.e., , while radiation is anything which scales to the inverse fourth power of the scale factor (). This can be understood intuitively: for an ordinary particle in a cube-shaped box, doubling the length of an edge of the box decreases the density (and hence energy density) by a factor of eight (2). For radiation, the decrease in energy density is greater, because an increase in spatial distance also causes a redshift.


title: Dark energy

text: The final component is dark energy: it is an intrinsic property of space and has a constant energy density, regardless of the dimensions of the volume under consideration (). Thus, unlike ordinary matter, it is not diluted by the expansion of space.


title: Dark energy

text: In 1998, the High-Z Supernova Search Team published observations of Type Ia ("one-A") supernovae. In 1999, the Supernova Cosmology Project followed by suggesting that the expansion of the universe is accelerating. The 2011 Nobel Prize in Physics was awarded to Saul Perlmutter, Brian P. Schmidt, and Adam G. Riess for their leadership in the discovery.


title: Dark energy

text: Since then, these observations have been corroborated by several independent sources. Measurements of the cosmic microwave background, gravitational lensing, and the large-scale structure of the cosmos, as well as improved measurements of supernovae, have been consistent with the Lambda-CDM model. Some people argue that the only indications for the existence of dark energy are observations of distance measurements and their associated redshifts. Cosmic microwave background anisotropies and baryon acoustic oscillations serve only to demonstrate that distances to a given redshift are larger than would be expected from a "dusty" Friedmann–Lemaître universe and the local measured Hubble constant.


title: Dark energy

text: Supernovae are useful for cosmology because they are excellent standard candles across cosmological distances. They allow researchers to measure the expansion history of the universe by looking at the relationship between the distance to an object and its redshift, which gives how fast it is receding from us. The relationship is roughly linear, according to Hubble's law. It is relatively easy to measure redshift, but finding the distance to an object is more difficult. Usually, astronomers use standard candles: objects for which the intrinsic brightness, or absolute magnitude, is known. This allows the object's distance to be measured from its actual observed brightness, or apparent magnitude. Type Ia supernovae are the best-known standard candles across cosmological distances because of their extreme and consistent luminosity.


title: Dark energy

text: Recent observations of supernovae are consistent with a universe made up 71.3% of dark energy and 27.4% of a combination of dark matter and baryonic matter.


title: Dark energy

text: The existence of dark energy, in whatever form, is needed to reconcile the measured geometry of space with the total amount of matter in the universe. Measurements of cosmic microwave background (CMB) anisotropies indicate that the universe is close to flat. For the shape of the universe to be flat, the mass–energy density of the universe must be equal to the critical density. The total amount of matter in the universe (including baryons and dark matter), as measured from the CMB spectrum, accounts for only about 30% of the critical density. This implies the existence of an additional form of energy to account for the remaining 70%. The Wilkinson Microwave Anisotropy Probe (WMAP) spacecraft seven-year analysis estimated a universe made up of 72.8% dark energy, 22.7% dark matter, and 4.5% ordinary matter.


title: Dark energy

text: Work done in 2013 based on the Planck spacecraft observations of the CMB gave a more accurate estimate of 68.3% dark energy, 26.8% dark matter, and 4.9% ordinary matter.


title: Dark energy

text: The theory of large-scale structure, which governs the formation of structures in the universe (stars, quasars, galaxies and galaxy groups and clusters), also suggests that the density of matter in the universe is only 30% of the critical density.


title: Dark energy

text: A 2011 survey, the WiggleZ galaxy survey of more than 200,000 galaxies, provided further evidence towards the existence of dark energy, although the exact physics behind it remains unknown. The WiggleZ survey from the Australian Astronomical Observatory scanned the galaxies to determine their redshift. Then, by exploiting the fact that baryon acoustic oscillations have left voids regularly of ≈150 Mpc diameter, surrounded by the galaxies, the voids were used as standard rulers to estimate distances to galaxies as far as 2,000 Mpc (redshift 0.6), allowing for accurate estimate of the speeds of galaxies from their redshift and distance. The data confirmed cosmic acceleration up to half of the age of the universe (7 billion years) and constrain its inhomogeneity to 1 part in 10. This provides a confirmation to cosmic acceleration independent of supernovae.


title: Dark energy

text: Accelerated cosmic expansion causes gravitational potential wells and hills to flatten as photons pass through them, producing cold spots and hot spots on the CMB aligned with vast supervoids and superclusters. This so-called late-time Integrated Sachs–Wolfe effect (ISW) is a direct signal of dark energy in a flat universe. It was reported at high significance in 2008 by Ho "et al." and Giannantonio "et al."


title: Dark energy

text: A new approach to test evidence of dark energy through observational Hubble constant data (OHD), also known as cosmic chronometers, has gained significant attention in recent years.


title: Dark energy

text: The Hubble constant, "H"("z"), is measured as a function of cosmological redshift. OHD directly tracks the expansion history of the universe by taking passively evolving early-type galaxies as "cosmic chronometers". From this point, this approach provides standard clocks in the universe. The core of this idea is the measurement of the differential age evolution as a function of redshift of these cosmic chronometers. Thus, it provides a direct estimate of the Hubble parameter


title: Dark energy

text: The reliance on a differential quantity, brings more information and is appealing for computation: It can minimize many common issues and systematic effects. Analyses of supernovae and baryon acoustic oscillations (BAO) are based on integrals of the Hubble parameter, whereas measures it directly. For these reasons, this method has been widely used to examine the accelerated cosmic expansion and study properties of dark energy.


title: Dark energy

text: Dark energy's status as a hypothetical force with unknown properties makes it a very active target of research. The problem is attacked from a great variety of angles, such as modifying the prevailing theory of gravity (general relativity), attempting to pin down the properties of dark energy, and finding alternative ways to explain the observational data.


title: Dark energy

text: The simplest explanation for dark energy is that it is an intrinsic, fundamental energy of space. This is the cosmological constant, usually represented by the Greek letter (Lambda, hence Lambda-CDM model). Since energy and mass are related according to the equation Einstein's theory of general relativity predicts that this energy will have a gravitational effect. It is sometimes called a "vacuum energy" because it is the energy density of empty space – the vacuum.


title: Dark energy

text: A major outstanding problem is that the same quantum field theories predict a huge cosmological constant, about 120 orders of magnitude too large. This would need to be almost, but not exactly, cancelled by an equally large term of the opposite sign.


title: Dark energy

text: Some supersymmetric theories require a cosmological constant that is exactly zero. Also, it is unknown if there is a metastable vacuum state in string theory with a positive cosmological constant, and it has been conjectured by Ulf Danielsson "et al." that no such state exists. This conjecture would not rule out other models of dark energy, such as quintessence, that could be compatible with string theory.


title: Dark energy

text: In quintessence models of dark energy, the observed acceleration of the scale factor is caused by the potential energy of a dynamical field, referred to as quintessence field. Quintessence differs from the cosmological constant in that it can vary in space and time. In order for it not to clump and form structure like matter, the field must be very light so that it has a large Compton wavelength. In the simplest scenarios, the quintessence field has a canonical kinetic term, is minimally coupled to gravity, and does not feature higher order operations in its Lagrangian.


title: Dark energy

text: No evidence of quintessence is yet available, but it has not been ruled out either. It generally predicts a slightly slower acceleration of the expansion of the universe than the cosmological constant. Some scientists think that the best evidence for quintessence would come from violations of Einstein's equivalence principle and variation of the fundamental constants in space or time. Scalar fields are predicted by the Standard Model of particle physics and string theory, but an analogous problem to the cosmological constant problem (or the problem of constructing models of cosmological inflation) occurs: renormalization theory predicts that scalar fields should acquire large masses.


title: Dark energy

text: The coincidence problem asks why the acceleration of the Universe began when it did. If acceleration began earlier in the universe, structures such as galaxies would never have had time to form, and life, at least as we know it, would never have had a chance to exist. Proponents of the anthropic principle view this as support for their arguments. However, many models of quintessence have a so-called "tracker" behavior, which solves this problem. In these models, the quintessence field has a density which closely tracks (but is less than) the radiation density until matter–radiation equality, which triggers quintessence to start behaving as dark energy, eventually dominating the universe. This naturally sets the low energy scale of the dark energy.


title: Dark energy

text: In 2004, when scientists fit the evolution of dark energy with the cosmological data, they found that the equation of state had possibly crossed the cosmological constant boundary (w = −1) from above to below. A no-go theorem has been proved that this scenario requires models with at least two types of quintessence. This scenario is the so-called Quintom scenario.


title: Dark energy

text: Some special cases of quintessence are phantom energy, in which the energy density of quintessence actually increases with time, and k-essence (short for kinetic quintessence) which has a non-standard form of kinetic energy such as a negative kinetic energy. They can have unusual properties: phantom energy, for example, can cause a Big Rip.


title: Dark energy

text: A group of researchers argued in 2021 that observations of the Hubble tension may imply that only quintessence models with a nonzero coupling constant are viable.


title: Dark energy

text: This class of theories attempts to come up with an all-encompassing theory of both dark matter and dark energy as a single phenomenon that modifies the laws of gravity at various scales. This could, for example, treat dark energy and dark matter as different facets of the same unknown substance, or postulate that cold dark matter decays into dark energy. Another class of theories that unifies dark matter and dark energy are suggested to be covariant theories of modified gravities. These theories alter the dynamics of the spacetime such that the modified dynamics stems to what have been assigned to the presence of dark energy and dark matter. Dark energy could in principle interact not only with the rest of the dark sector, but also with ordinary matter. However, cosmology alone is not sufficient to effectively constrain the strength of the coupling between dark energy and baryons, so that other indirect techniques or laboratory searches have to be adopted. A recent proposal speculates that the currently unexplained excess observed in the XENON1T detector in Italy may have been caused by a chameleon model of dark energy. In July 2022 a new analysis by XENONnT discarded the excess.


title: Dark energy

text: The density of dark energy might have varied in time during the history of the universe. Modern observational data allows us to estimate the present density of dark energy. Using baryon acoustic oscillations, it is possible to investigate the effect of dark energy in the history of the Universe, and constrain parameters of the equation of state of dark energy. To that end, several models have been proposed. One of the most popular models is the Chevallier–Polarski–Linder model (CPL). Some other common models are, (Barboza & Alcaniz. 2008), (Jassal et al. 2005), (Wetterich. 2004), (Oztas et al. 2018).


title: Dark energy

text: Some alternatives to dark energy, such as inhomogeneous cosmology, aim to explain the observational data by a more refined use of established theories. In this scenario, dark energy doesn't actually exist, and is merely a measurement artifact. For example, if we are located in an emptier-than-average region of space, the observed cosmic expansion rate could be mistaken for a variation in time, or acceleration. A different approach uses a cosmological extension of the equivalence principle to show how space might appear to be expanding more rapidly in the voids surrounding our local cluster. While weak, such effects considered cumulatively over billions of years could become significant, creating the illusion of cosmic acceleration, and making it appear as if we live in a Hubble bubble. Yet other possibilities are that the accelerated expansion of the universe is an illusion caused by the relative motion of us to the rest of the universe, or that the statistical methods employed were flawed. It has also been suggested that the anisotropy of the local Universe has been misrepresented as dark energy. This claim was quickly countered by others, including a paper by physicists D. Rubin and J. Heitlauf. A laboratory direct detection attempt failed to detect any force associated with dark energy.


title: Dark energy

text: A study published in 2020 questioned the validity of the essential assumption that the luminosity of Type Ia supernovae does not vary with stellar population age, and suggests that dark energy may not actually exist. Lead researcher of the new study, Young-Wook Lee of Yonsei University, said "Our result illustrates that dark energy from SN cosmology, which led to the 2011 Nobel Prize in Physics, might be an artifact of a fragile and false assumption." Multiple issues with this paper were raised by other cosmologists, including Adam Riess, who won the 2011 Nobel Prize for the discovery of dark energy.


title: Dark energy

text: The evidence for dark energy is heavily dependent on the theory of general relativity. Therefore, it is conceivable that a modification to general relativity also eliminates the need for dark energy. There are very many such theories, and research is ongoing. The measurement of the speed of gravity in the first gravitational wave measured by non-gravitational means (GW170817) ruled out many modified gravity theories as explanations to dark energy.


title: Dark energy

text: Astrophysicist Ethan Siegel states that, while such alternatives gain a lot of mainstream press coverage, almost all professional astrophysicists are confident that dark energy exists, and that none of the competing theories successfully explain observations to the same level of precision as standard dark energy.


title: Dark energy

text: "Taken together, all the current data provide strong evidence for the existence of dark energy; they constrain the fraction of critical density contributed by dark energy, and the equation-of-state parameter:


title: Dark energy

text: assuming that    is constant. This implies that the Universe began accelerating at redshift and age These results are robust – data from any one method can be removed without compromising the constraints – and they are not substantially weakened by dropping the assumption of spatial flatness."


title: Dark energy

text: Before that, it is thought that the expansion was decelerating, due to the attractive influence of matter. The density of dark matter in an expanding universe decreases more quickly than dark energy, and eventually the dark energy dominates. Specifically, when the volume of the universe doubles, the density of dark matter is halved, but the density of dark energy is nearly unchanged (it is exactly constant in the case of a cosmological constant).


title: Dark energy

text: Projections into the future can differ radically for different models of dark energy. For a cosmological constant, or any other model that predicts that the acceleration will continue indefinitely, the ultimate result will be that galaxies outside the Local Group will have a line-of-sight velocity that continually increases with time, eventually far exceeding the speed of light. This is not a violation of special relativity because the notion of "velocity" used here is different from that of velocity in a local inertial frame of reference, which is still constrained to be less than the speed of light for any massive object (see Uses of the proper distance for a discussion of the subtleties of defining any notion of relative velocity in cosmology). Because the Hubble parameter is decreasing with time, there can actually be cases where a galaxy that is receding from us faster than light does manage to emit a signal which reaches us eventually.


title: Dark energy

text: However, because of the accelerating expansion, it is projected that most galaxies will eventually cross a type of cosmological event horizon where any light they emit past that point will never be able to reach us at any time in the infinite future because the light never reaches a point where its "peculiar velocity" toward us exceeds the expansion velocity away from us (these two notions of velocity are also discussed in Uses of the proper distance). Assuming the dark energy is constant (a cosmological constant), the current distance to this cosmological event horizon is about 16 billion light years, meaning that a signal from an event happening "at present" would eventually be able to reach us in the future if the event were less than 16 billion light years away, but the signal would never reach us if the event were more than 16 billion light years away.


title: Dark energy

text: As galaxies approach the point of crossing this cosmological event horizon, the light from them will become more and more redshifted, to the point where the wavelength becomes too large to detect in practice and the galaxies appear to vanish completely ("see" Future of an expanding universe). Planet Earth, the Milky Way, and the Local Group of which the Milky Way is a part, would all remain virtually undisturbed as the rest of the universe recedes and disappears from view. In this scenario, the Local Group would ultimately suffer heat death, just as was hypothesized for the flat, matter-dominated universe before measurements of cosmic acceleration.


title: Dark energy

text: There are other, more speculative ideas about the future of the universe. The phantom energy model of dark energy results in "divergent" expansion, which would imply that the effective force of dark energy continues growing until it dominates all other forces in the universe. Under this scenario, dark energy would ultimately tear apart all gravitationally bound structures, including galaxies and solar systems, and eventually overcome the electrical and nuclear forces to tear apart atoms themselves, ending the universe in a "Big Rip". On the other hand, dark energy might dissipate with time or even become attractive. Such uncertainties leave open the possibility of gravity eventually prevailing and lead to a universe that contracts in on itself in a "Big Crunch", or that there may even be a dark energy cycle, which implies a cyclic model of the universe in which every iteration (Big Bang then eventually a Big Crunch) takes about a trillion (10) years. While none of these are supported by observations, they are not ruled out.


title: Dark energy

text: The astrophysicist David Merritt identifies dark energy as an example of an "auxiliary hypothesis", an ad hoc postulate that is added to a theory in response to observations that falsify it. He argues that the dark energy hypothesis is a conventionalist hypothesis, that is, a hypothesis that adds no empirical content and hence is unfalsifiable in the sense defined by Karl Popper.


title: Kuala Lumpur International Airport

text: Kuala Lumpur International Airport (KLIA) is Malaysia's main international airport. It is located in the Sepang District of Selangor, approximately south of Kuala Lumpur and serves the city's greater conurbation.


title: Kuala Lumpur International Airport

text: KLIA is the largest and busiest airport in Malaysia. In 2020, it handled 13,156,363 passengers, 505,184 tonnes of cargo and 124,529 aircraft movements. It is the world's 23rd-busiest airport by total passenger traffic.


title: Kuala Lumpur International Airport

text: The airport is operated by Malaysia Airports (MAHB) Sepang Sdn Bhd and is the major hub of Malaysia Airlines, MASkargo, Batik Air Malaysia, UPS Airlines and World Cargo Airlines, and the major operating base of AirAsia, AirAsia X and MYAirline.


title: Kuala Lumpur International Airport

text: The ground breaking ceremony for Kuala Lumpur International Airport (KLIA) took place on 1 June 1993 when the government under Mahathir Mohamad decided that the existing Kuala Lumpur airport, then known as Subang International Airport (now Sultan Abdul Aziz Shah Airport) could not handle future demand. The construction of the airport was done mainly by a few state owned construction companies as well as Ekovest Berhad – helmed by Tan Sri Datuk Lim Kang Hoo. It was created as part of the Multimedia Super Corridor, a grand development plan for Malaysia. The chief architect who designed the new airport terminal was the Japanese architect Kisho Kurokawa.


title: Kuala Lumpur International Airport

text: Upon KLIA's completion, Subang Airport's Terminal 1 building was demolished. Malaysia Airports agreed to redevelop the remaining Terminal 3 to create a specialist airport for turboprop and charter planes surrounded by a residential area and a business park. The IATA airport code KUL was transferred from Subang Airport, which currently handles only turboprop aircraft, general aviation and military aircraft.


title: Kuala Lumpur International Airport

text: The airport's site spans , of former agricultural land and is one of the world's largest airport sites. An ambitious three-phase development plan anticipates KLIA to have three runways and two terminals each with two satellite terminals. Phase One involved the construction of the main terminal and one satellite terminal, giving a capacity of 25 million passengers, and two full service runways. The Phase One airport had sixty contact piers, twenty remote parking bays with eighty aircraft parking positions, four maintenance hangars and fire stations. Phase Two, designed to increase capacity to 35 million passengers per year is largely complete. Phase Three is anticipated to increase capacity to 100 million passengers per year.


title: Kuala Lumpur International Airport

text: Kuala Lumpur International Airport was officially inaugurated by the tenth Yang di-Pertuan Agong, Tuanku Ja'afar of Negeri Sembilan, on 27 June 1998 at 20:30 MST. The first domestic arrival was Malaysia Airlines flight MH1263 from Kuantan at 07:10 MST. The first international arrival was Malaysia Airlines flight MH188 from Malé at 07:30 MST. The first domestic departure was Malaysia Airlines flight MH1432 to Langkawi at 07:20 MST; the first international departure was Malaysia Airlines flight MH84 to Beijing at 09:00 MST.


title: Kuala Lumpur International Airport

text: The inauguration of the airport was marked with numerous problems. The aerobridge and bay allocation systems broke down, with queues building up throughout the airport and the baggage handling breaking down. Bags were lost, and there were waits of over five to seven hours. Most of these issues were remedied eventually, though the baggage handling system was plagued with problems until it was put up for a complete replacement tender in 2007.


title: Kuala Lumpur International Airport

text: The airport suffered greatly reduced traffic with the general reduction in economic activity brought about by the 1997 Asian financial crisis, SARS, bird flu epidemic (Avian flu), the financial crisis of 2007–2008, the 2009 swine flu pandemic and the COVID-19 pandemic. The airport is also largely overshadowed by the more internationally renowned Changi Airport located approximately to the south in Singapore, especially in regards to connecting flights by various airlines or Malaysians especially living in the southern parts of the country (e.g. Johor) preferring to travel via Changi rather than at KLIA.