Artificial gravity is the creation of an inertial force that mimics the effects of a gravitational force by rotation. Artificial gravity, or rotational gravity, is thus the appearance of a centrifugal force in a rotating frame of reference, as opposed to the force experienced in linear acceleration, which by the equivalence principle is indistinguishable from gravity. In a more general sense, "artificial gravity" may refer to the effect of linear acceleration, e.g. by means of a rocket engine. Rotational simulated gravity has been used in simulations to help astronauts train for extreme conditions. Rotational simulated gravity has been proposed as a solution in manned spaceflight to the adverse health effects caused by prolonged weightlessness. However, there are no current practical outer space applications of artificial gravity for humans due to concerns about the size and cost of a spacecraft necessary to produce a useful centripetal acceleration comparable to the gravitational field strength on Earth.
Artificial gravity can be created using a centripetal force. A centripetal force directed towards the center of the turn is required for any object to move in a circular path. In the context of a rotating space station it is the normal force provided by spacecraft's hull that acts as centripetal force. Thus, the "gravity" force felt by an object the centrifugal force perceived in the rotating frame of reference as pointing "downwards" towards the hull. In accordance with Newton's Third Law the value of little g is equal in magnitude and opposite in direction to the centripetal acceleration. From the point of view of people rotating with the habitat, artificial gravity by rotation behaves in some ways to normal gravity but with the following differences: Centripetal force: Unlike real gravity, which pulls towards a center of the planet, the centripetal force pushes towards the axis of rotation. For a given angular velocity the amount of artificial gravity depends linearly on the radius. With a small radius of rotation, the amount of gravity felt at one's head would be different from the amount felt at one's feet.
This could make changing body position awkward. In accordance with the physics involved, slower rotations or larger rotational radii would reduce or eliminate this problem; the linear velocity of the habitat should be higher than the relative velocities with which an astronaut will change position within it. Otherwise moving in the direction of the rotation will increase the felt gravity to the point that it should cause problems; the Coriolis effect gives an apparent force that acts on objects that move relative to a rotating reference frame. This apparent force acts at right angles to the motion and the rotation axis and tends to curve the motion in the opposite sense to the habitat's spin. If an astronaut inside a rotating artificial gravity environment moves towards or away from the axis of rotation, he or she will feel a force pushing him or her towards or away from the direction of spin; these forces act on the inner ear and can cause dizziness and disorientation. Lengthening the period of rotation reduces the Coriolis force and its effects.
It is believed that at 2 rpm or less, no adverse effects from the Coriolis forces will occur, although humans have been shown to adapt to rates as high as 23 rpm. It is not yet known whether long exposures to high levels of Coriolis forces can increase the likelihood of becoming accustomed; the nausea-inducing effects of Coriolis forces can be mitigated by restraining movement of the head. This form of artificial gravity has additional engineering issues: Kinetic energy and angular momentum: Spinning up parts or all of the habitat requires energy, while angular momentum must be conserved; this would require a propulsion system and expendable propellant, or could be achieved without expending mass, by an electric motor and a counterweight, such as a reaction wheel or another living area spinning in the opposite direction. Extra strength is needed in the structure to keep it from flying apart because of the rotation. However, the amount of structure needed over and above that to hold a breathable atmosphere is modest for most structures.
If parts of the structure are intentionally not spinning and similar torques will cause the rates of spin to converge, requiring motors and power to be used to compensate for the losses due to friction. A traversable interface between parts of the station spinning relative to each other requires large vacuum-tight axial seals; the engineering challenges of creating a rotating spacecraft are comparatively modest to any other proposed approach. Theoretical spacecraft designs using artificial gravity have a great number of variants with intrinsic problems and advantages; the formula for the centripetal force implies that the radius of rotation grows with the square of the rotating spacecraft period, so a doubling of the period requires a fourfold increase in the radius of rotation. For example, to produce standard gravity, ɡ0 = 9.80665 m/s2 with a rotating spacecraft period of 15 s, the radius of rotation would have to be 56 m, while a period of 30 s would require it to be 224 m. To reduce mass, the support along the diameter could consist of nothing but a cable connecting two sections of the spaceship.
Among the possible solutions include a habitat module and a counterweight c
Space colonization is permanent human habitation off the planet Earth. Many arguments have been made against space colonization; the two most common in favor of colonization are survival of human civilization and the biosphere in the event of a planetary-scale disaster, the availability of additional resources in space that could enable expansion of human society. The most common objections to colonization include concerns that the commodification of the cosmos may be to enhance the interests of the powerful, including major economic and military institutions, to exacerbate pre-existing detrimental processes such as wars, economic inequality, environmental degradation. No space colonies have been built so far; the building of a space colony would present a set of huge technological and economic challenges. Space settlements would have to provide for nearly all the material needs of hundreds or thousands of humans, in an environment out in space, hostile to human life, they would involve technologies, such as controlled ecological life support systems, that have yet to be developed in any meaningful way.
They would have to deal with the as-yet unknown issue of how humans would behave and thrive in such places long-term. Because of the present cost of sending anything from the surface of the Earth into orbit, a space colony would be a massively expensive project. There are yet no plans for building space colonies by any large-scale organization, either government or private. However, many proposals and designs for space settlements have been made through the years, a considerable number of space colonization advocates and groups are active. Several famous scientists, such as Freeman Dyson, have come out in favor of space settlement. On the technological front, there is ongoing progress in making access to space cheaper, in creating automated manufacturing and construction techniques; the primary argument calling for space colonization is the long-term survival of human civilization. By developing alternative locations off Earth, the planet's species, including humans, could live on in the event of natural or man-made disasters on our own planet.
On two occasions, theoretical physicist and cosmologist Stephen Hawking has argued for space colonization as a means of saving humanity. In 2001, Hawking predicted that the human race would become extinct within the next thousand years, unless colonies could be established in space. In 2006, he stated that humanity faces two options: either we colonize space within the next two hundred years and build residential units on other planets, or we will face the prospect of long-term extinction. In 2005 NASA Administrator Michael Griffin identified space colonization as the ultimate goal of current spaceflight programs, saying:... the goal isn't just scientific exploration... it's about extending the range of human habitat out from Earth into the solar system as we go forward in time... In the long run a single-planet species will not survive... If we humans want to survive for hundreds of thousands of millions of years, we must populate other planets. Now, today the technology is such that this is conceivable.
We're in the infancy of it.... I'm talking about that one day, I don't know when that day is, but there will be more human beings who live off the Earth than on it. We may well have people living on the Moon. We may have people living on the moons of other planets. We may have people making habitats on asteroids... I know that humans will colonize one day go beyond. Louis J. Halle of the United States Department of State, wrote in Foreign Affairs that the colonization of space will protect humanity in the event of global nuclear warfare; the physicist Paul Davies supports the view that if a planetary catastrophe threatens the survival of the human species on Earth, a self-sufficient colony could "reverse-colonize" Earth and restore human civilization. The author and journalist William E. Burrows and the biochemist Robert Shapiro proposed a private project, the Alliance to Rescue Civilization, with the goal of establishing an off-Earth "backup" of human civilization. Based on his Copernican principle, J. Richard Gott has estimated that the human race could survive for another 7.8 million years, but it is not to colonize other planets.
However, he expressed a hope to be proven wrong, because "colonizing other worlds is our best chance to hedge our bets and improve the survival prospects of our species". Resources in space, both in materials and energy, are enormous; the Solar System alone has, according to different estimates, enough material and energy to support anywhere from several thousand to over a billion times that of the current Earth-based human population. Outside the Solar System, several hundred billion other planets in the Milky Way alone provide opportunities for both colonization and resource collection, though travel to any of them is impossible on any practical time-scale without interstellar travel by use of generation ships or revolutionary new methods of travel, such as faster-than-light. Asteroid mining will be a key player in space colonization. Water and materials to make structures and shielding can be found in asteroids. Instead of resupplying on Earth and fuel stations need to be established on asteroids to facilitate better space travel.
Optical mining is the term. NASA believes by using propellant derived from asteroids for
A referendum is a direct vote in which an entire electorate is invited to vote on a particular proposal. This may result in the adoption of a new law. In some countries, it is synonymous with a vote on a ballot question; some definitions of'plebiscite' suggest that it is a type of vote to change the constitution or government of a country. However, some other countries define it differently. For example, Australia defines'referendum' as a vote to change the constitution, and'plebiscite' as a vote that does not affect the constitution. In Ireland, the vote to adopt its constitution was called a "plebiscite", but a subsequent vote to amend the constitution is called a'referendum', so is a poll of the electorate on a non-constitutional bill; the word referendum is a general word used for both legislative referrals and initiatives.'Referendum' is the gerundive form of the Latin verb refero "to carry back". As a gerundive is an adjective, not a noun, it cannot be used alone in Latin and must be contained within a context attached to a noun such as Propositum quod referendum est populo, "A proposal which must be carried back to the people".
The addition of the verb sum to a gerundive, denotes the idea of necessity or compulsion, that which "must" be done, rather than that, "fit for" doing. Its use as a noun in English is thus not a grammatical usage of a foreign word, but is rather a freshly coined English noun, which therefore follows English grammatical usage, not Latin grammatical usage; this determines the form of the plural in English, which according to English grammar should be "referendums". The use of "referenda" as a plural form in English is thus insupportable according to the rules of both Latin and English grammar alike; the use of "referenda" as a plural form is posited hypothetically as either a gerund or a gerundive by the Oxford English Dictionary, which rules out such usage in both cases as follows: Referendums is logically preferable as a plural form meaning'ballots on one issue'. The Latin plural gerundive'referenda', meaning'things to be referred' connotes a plurality of issues, it is related to the political agenda, "those matters which must be driven forward", from ago, to drive.
The name and use of the'referendum' is thought to have originated in the Swiss canton of Graubünden as early as the 16th century. The term'plebiscite' has a similar meaning in modern usage, comes from the Latin plebiscita, which meant a decree of the Concilium Plebis, the popular assembly of the Roman Republic. Today, a referendum can often be referred to as a plebiscite, but in some countries the two terms are used differently to refer to votes with differing types of legal consequences. For example, Australia defines'referendum' as a vote to change the constitution, and'plebiscite' as a vote that does not affect the constitution. In contrast, Ireland has only held one plebiscite, the vote to adopt its constitution, every other vote has been called a referendum. Plebiscite has been used to denote a non-binding vote count such as the one held by Nazi Germany to'approve' in retrospect the so-called Anschluss with Austria, the question being not'Do you permit?' but rather'Do you approve?' of that which has most already occurred.
The term referendum covers a variety of different meanings. A referendum can be advisory. In some countries, different names are used for these two types of referendum. Referendums can be further classified by who initiates them: mandatory referendums prescribed by law, voluntary referendums initiated by the legislature or government, referendums initiated by citizens. A deliberative referendum is a referendum designed to improve the deliberative qualities of the campaign preceding the referendum vote, and/or of the act of voting itself. From a political-philosophical perspective, referendums are an expression of direct democracy. However, in the modern world, most referendums need to be understood within the context of representative democracy. Therefore, they tend to be used quite selectively, covering issues such as changes in voting systems, where elected officials may not have the legitimacy or inclination to implement such changes. Since the end of the 18th century, hundreds of national referendums have been organised in the world.
Italy ranked second with 72 national referendums: 67 popular referendums, 3 constitutional referendums, one institutional referendum and one advisory referendum. A referendum offers the electorate a choice of accepting or rejecting a proposal, but not always; some referendums give voters the choice among multiple choices and some use Transferable voting even. In Switzerland, for example, multiple choice referendums are common. Two multiple choice referendums were held in Sweden, in 1957 and in 1980, in which voters were offered three options. In 1977, a referendum held in Australia to determine a new national anthem was held in which voters had four choices. In 1992, New Zealand held a five-option referendum on their electoral system. In 1982, Guam had referendum that used six options, with an additional blank option for anyone wishing to vote for their own seventh option. A multiple choice referendum pose
Surface Detail by Iain M. Banks is a science fiction novel in his Culture series, first published in the UK on 7 October 2010 and the US on 28 October 2010; the events of Surface Detail take place around 2970 AD, according to Banks. The events occur six to eight hundred years after the "Chel Debacle", depicted in the earlier novel Look to Windward, set seventy-eight years after the events in Use of Weapons; each chapter of the book covers one or more of the six main protagonists—Lededje Y'breq, a chattel slave. Some of the plot occurs in simulated environments; as the book begins, a war game—the "War in Heaven"—has been running for several decades. The outcome of the simulated war will determine whether societies are allowed to run artificial Hells, virtual afterlives in which the mind-states of the dead are tortured; the Culture, fiercely anti-Hell, has opted to stay out of the war while accepting the outcome as binding. Vatueil is a soldier who has fought his way up the ranks of the war game to a position where he can determine policy.
He is instrumental in the decision to cheat—first by attempting to hack into and subvert the war-game, when this fails by moving the simulated war into the real world. Prin and Chay belong to a species that use the threat of Hell to control the behaviour of their population. While still alive, they enter the Pavulean Hell on a mission to reveal the existence and details of this Hell to the general population. Prin succeeds in getting out, but has to leave his partner Chay behind, where she is subsequently tortured, restored to some semblance of sanity, given a role as an angel in Hell, able to release one soul a day by killing them. Prin testifies to the Pavulean parliament of his experience in Hell and attempts to convince them that it should be abolished. Veppers is the richest individual in the multi-planet Sichultian Enablement. Y' breq, a frequent victim of rape by Veppers, is murdered by him, she is unexpectedly reincarnated aboard a Culture ship, having been secretly implanted with a neural lace some ten years before.
She wants to return to her homeworld, to find and kill Veppers. The book hinges on Veppers' involvement in the War in Heaven, he appears to be a bit-player, but his involvement is revealed to be more and more critical. The final revelation is that he has made some of his fortune by providing the hardware to run the Hells of various species; the hardware is located on his country estate on the planet Sichult. He sets up a secret deal to have the Hells destroyed in an attack, to be blamed upon the Culture, his motivation is that such an attack will release him from his contracts to run the Hells, which would have become worthless if the anti-Hell side won, but which he cannot wriggle out of in any other way. Y'breq travels back to Sichult on the Falling Outside The Normal Moral Constraints, an advanced and "very psychotic" Culture warship. In hot pursuit is Yime Nsokyi, a Culture agent tasked with preventing Y'breq from killing Veppers; as they and their ships arrive, things come to a head. The Culture agents conspire to arrange that the attack on Veppers' estate destroys the Hells, while appearing to attempt to stop the attack.
They conspire to ensure that Veppers' secret deal is revealed. Veppers himself is at the estate's mansion during the attack, where Y'breq finds him for the final, showdown; the epilogue reveals Vatueil's identity as Zakalwe, using an alias, an anagram of Livueta, the character in Use of Weapons whose forgiveness Zakalwe sought. Roz Kaveney of The Independent said that this was a poor book to introduce new readers to the Culture, but "far from the worst introduction to Banks's series." Alastair Mabbott of The Herald describes the story as having "murder, revenge and subterfuge taking place against a backdrop of escalating tension stands up well, makes the prospect of further books in the Culture series somewhat less imposing." UK book review site The Bookbag remarked that "... What sets this book apart is the quality of the writing and the depth of the author's imagination." Simulated reality Simulated reality in fiction
A continent is one of several large landmasses of the world. Identified by convention rather than any strict criteria, up to seven regions are regarded as continents. Ordered from largest in area to smallest, they are: Asia, North America, South America, Antarctica and Australia. Geologically, the continents correspond to areas of continental crust that are found on the continental plates. However, some areas of continental crust are regions covered with water not included in the list of continents. Zealandia is one such area. Islands are grouped with a neighbouring continent to divide all the world's land into geopolitical regions. Under this scheme, most of the island countries and territories in the Pacific Ocean are grouped together with the continent of Australia to form a geopolitical region called Oceania. By convention, "continents are understood to be large, discrete masses of land, ideally separated by expanses of water." Several of the seven conventionally recognized continents are not discrete landmasses separated by water.
The criterion "large" leads to arbitrary classification: Greenland, with a surface area of 2,166,086 square kilometres is considered the world's largest island, while Australia, at 7,617,930 square kilometres is deemed the smallest continent. Earth's major landmasses all have coasts on a single, continuous World Ocean, divided into a number of principal oceanic components by the continents and various geographic criteria; the most restricted meaning of continent is that of a continuous area of land or mainland, with the coastline and any land boundaries forming the edge of the continent. In this sense the term continental Europe is used to refer to mainland Europe, excluding islands such as Great Britain, Ireland and Iceland, the term continent of Australia may refer to the mainland of Australia, excluding Tasmania and New Guinea; the continental United States refers to the 48 contiguous states and the District of Columbia in central North America and may include Alaska in the northwest of the continent, while excluding Hawaii, Puerto Rico, Guam in the oceans.
From the perspective of geology or physical geography, continent may be extended beyond the confines of continuous dry land to include the shallow, submerged adjacent area and the islands on the shelf, as they are structurally part of the continent. From this perspective, the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level. In this sense the islands of Great Britain and Ireland are part of Europe, while Australia and the island of New Guinea together form a continent; as a cultural construct, the concept of a continent may go beyond the continental shelf to include oceanic islands and continental fragments. In this way, Iceland is considered Madagascar part of Africa. Extrapolating the concept to its extreme, some geographers group the Australian continental plate with other islands in the Pacific into one continent called Oceania; this divides the entire land surface of Earth into quasi-continents. The ideal criterion that each continent is a discrete landmass is relaxed due to historical conventions.
Of the seven most globally recognized continents, only Antarctica and Australia are separated from other continents by the ocean. Several continents are defined not as distinct bodies but as "more or less discrete masses of land". Asia and Africa are joined by the Isthmus of Suez, North and South America by the Isthmus of Panama. In both cases, there is no complete separation of these landmasses by water. Both these isthmuses are narrow compared to the bulk of the landmasses they unite. North America and South America are treated as separate continents in the seven-continent model. However, they may be viewed as a single continent known as America or the Americas; this viewpoint was common in the United States until World War II, remains prevalent in some Asian six-continent models. This remains the more common vision in Latin American countries, Portugal, Italy and Hungary where they are taught as a single continent; the criterion of a discrete landmass is disregarded if the continuous landmass of Eurasia is classified as two separate continents: Europe and Asia.
Physiographically and South Asia are peninsulas of the Eurasian landmass. However, Europe is considered a continent with its comparatively large land area of 10,180,000 square kilometres, while South Asia, with less than half that area, is considered a subcontinent; the alternative view—in geology and geography—that Eurasia is a single continent results in a six-continent view of the world. Some view separation of Eurasia into Asia and Europe as a residue of Eurocentrism: "In physical and historical diversity and India are comparable to the entire European landmass, not to a single European country.." However, for historical and cultural reasons, the view of Europe as a separate continent continues in several categorizations. If continents are defined as discrete landmasses, embracing all the contiguous land of a body Africa and Europe form a single continent which may be referred to as Afro-Eurasia; this produces a four-continent model consisting of Afro-Eurasia, America and Australia. When sea levels were lower during the Pleistocene ice ages, gre
An ocean is a body of water that composes much of a planet's hydrosphere. On Earth, an ocean is one of the major conventional divisions of the World Ocean; these are, in descending order by area, the Pacific, Indian and Arctic Oceans. The word "ocean" is used interchangeably with "sea" in American English. Speaking, a sea is a body of water or enclosed by land, though "the sea" refers to the oceans. Saline water covers 361,000,000 km2 and is customarily divided into several principal oceans and smaller seas, with the ocean covering 71% of Earth's surface and 90% of the Earth's biosphere; the ocean contains 97% of Earth's water, oceanographers have stated that less than 5% of the World Ocean has been explored. The total volume is 1.35 billion cubic kilometers with an average depth of nearly 3,700 meters. As the world ocean is the principal component of Earth's hydrosphere, it is integral to life, forms part of the carbon cycle, influences climate and weather patterns; the World Ocean is the habitat of 230,000 known species, but because much of it is unexplored, the number of species that exist in the ocean is much larger over two million.
The origin of Earth's oceans is unknown. Extraterrestrial oceans may be composed of water or other compounds; the only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their geologic histories and Venus are theorized to have had large water oceans; the Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, a runaway greenhouse effect may have boiled away the global ocean of Venus. Compounds such as salts and ammonia dissolved in water lower its freezing point so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of natural satellites; the Solar System's giant planets are thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may exist on exoplanets and exomoons, including surface oceans of liquid water within a circumstellar habitable zone.
Ocean planets are a hypothetical type of planet with a surface covered with liquid. The word ocean comes from the figure in classical antiquity, the elder of the Titans in classical Greek mythology, believed by the ancient Greeks and Romans to be the divine personification of the sea, an enormous river encircling the world; the concept of Ōkeanós has an Indo-European connection. Greek Ōkeanós has been compared to the Vedic epithet ā-śáyāna-, predicated of the dragon Vṛtra-, who captured the cows/rivers. Related to this notion, the Okeanos is represented with a dragon-tail on some early Greek vases. Though described as several separate oceans, the global, interconnected body of salt water is sometimes referred to as the World Ocean or global ocean; the concept of a continuous body of water with free interchange among its parts is of fundamental importance to oceanography. The major oceanic divisions – listed below in descending order of area and volume – are defined in part by the continents, various archipelagos, other criteria.
Oceans are fringed by smaller, adjoining bodies of water such as seas, bays and straits. The mid-ocean ridges of the world are connected and form a single global mid-oceanic ridge system, part of every ocean and the longest mountain range in the world; the continuous mountain range is 65,000 km long. The total mass of the hydrosphere is about 1.4 quintillion metric tons, about 0.023% of Earth's total mass. Less than 3% is freshwater; the area of the World Ocean is about 361.9 million square kilometers, which covers about 70.9% of Earth's surface, its volume is 1.335 billion cubic kilometers. This can be thought of as a cube of water with an edge length of 1,101 kilometers, its average depth is about 3,688 meters, its maximum depth is 10,994 meters at the Mariana Trench. Nearly half of the world's marine waters are over 3,000 meters deep; the vast expanses of deep ocean cover about 66% of Earth's surface. This does not include seas not connected to the World Ocean, such as the Caspian Sea; the bluish ocean color is a composite of several contributing agents.
Prominent contributors include dissolved organic chlorophyll. Mariners and other seafarers have reported that the ocean emits a visible glow which extends for miles at night. In 2005, scientists announced that for the first time, they had obtained photographic evidence of this glow, it is most caused by bioluminescence. Oceanographers divide the ocean into different vertical zones defined by physical and biological conditions; the pelagic zone includes all open ocean regions, can be divided into further regions categorized by depth and light abundance. The photic zone includes the oceans from the surface to a depth of
A bulkhead is an upright wall within the hull of a ship or within the fuselage of an aeroplane. Other kinds of partition elements within a ship are deckheads; the word bulki meant "cargo" in Old Norse. Sometime in the 15th century sailors and builders in Europe realized that walls within a vessel would prevent cargo from shifting during passage. In shipbuilding, any vertical panel was called a "head". So walls installed abeam in a vessel's hull were called "bulkheads". Now, the term bulkhead applies except for the hull itself. Bulkhead partitions are considered to have been a type of ship. Song Dynasty author Zhu Yu wrote in his book of 1119 that the hulls of Chinese ships had a bulkhead build; the 5th-century book Garden of Strange Things by Liu Jingshu mentioned that a ship could allow water to enter the bottom without sinking. Archaeological evidence of bulkhead partitions has been found on a 24 m long Song Dynasty ship dredged from the waters off the southern coast of China in 1973, the hull of the ship divided into twelve walled compartmental sections built watertight, dated to about 1277.
Texts written by Western writers such as Marco Polo, Niccolò Da Conti, Benjamin Franklin describe the bulkhead partitions of East Asian shipbuilding. An account of the early fifteenth century describes Indian ships as being built in compartments so that if one part was damaged, the rest remained intact — a forerunner of the modern day watertight compartments using bulkheads. Bulkhead partitions became widespread in Western shipbuilding during the early 19th century. Benjamin Franklin wrote in a 1787 letter that "as these vessels are not to be laden with goods, their holds may without inconvenience be divided into separate apartments, after the Chinese manner, each of these apartments caulked tight so as to keep out water." A 19th century book on shipbuilding attributes the introduction of watertight bulkheads to Charles Wye Williams, known for his steamships. Bulkheads in a ship serve several purposes: increase the structural rigidity of the vessel, divide functional areas into rooms and create watertight compartments that can contain water in the case of a hull breach or other leak. some bulkheads and decks are fire-resistance rated to achieve compartmentalisation, a passive fire protection measure.
On an aircraft, bulkheads divide the cabin into multiple areas. On passenger aircraft a common application is for physically dividing cabins used for different classes of service On combination cargo/ passenger, or "combi" aircraft, bulkhead walls are inserted to divide areas intended for passenger seating and cargo storage. Openings in fire-resistance rated bulkheads and decks must be firestopped to restore the fire-resistance ratings that would otherwise be compromised, if the openings were left unsealed; the authority having jurisdiction for such measures varies depending upon the flag of the ship. Merchant vessels are subject to the regulations and inspections of the Coast Guards of the flag country. Combat ships are subject to the regulations set out by the navy of the country. Bulkheads and decks of warships may be grounded as a countermeasure against damage from EMI and EMP due to nuclear or electromagnetic bomb detonations near the ship, which could damage the vital electronic systems on a ship.
In the case of firestops, cable jacketing is removed within the seal and firestop rubber modules are internally fitted with copper shields, which contact the cables' armour in order to ground the seal. The term was applied to other vehicles, such as railroad cars, hopper cars, automobiles, aircraft or spacecraft, as well as to containers, intermediate bulk containers and fuel tanks. In some of these cases bulkheads are airtight to prevent the spread of a fire; the term may be used for the "end walls" of bulkhead flatcars. Mechanically, a partition or panel through which connectors pass, or a connector designed to pass through a partition. In architecture the term is used to denote any boxed in beam or other downstand from a ceiling and by extension the vertical downstand face of an area of lower ceiling beyond; this usage derives from experience on boats where to maintain the structural function personnel openings through bulkheads always retain a portion of the bulkhead crossing the head of the opening.
Head strikes on these downstand elements are commonplace hence in architecture any overhead downstand element comes to be referred to as a bulkhead. Britannica definition Merriam-Webster definition WIPO Bulkhead for motor vehicle Canadian Armed Forces Glossary, see Fire Zone, page 5 of 14 Det Norske Veritas Type Approval for a fire damper inside and A60 bulkhead Subject-related patent by Free Patents Online An example treatise on the use of A60 bulkheads onboard tankers