Vacuum

qas: question: The word Vacuum stems from what Latin adjective?
answers: text: vacuus

question: What does the term used by Physicists, partial vacuum, refer to?
answers: text: imperfect vacuum

question: What is a vacuum?
answers: text: space void of matter

question: What type of pressure is less than atmospheric pressure in a vacuum?
answers: text: gaseous

question: What Latin term is used to describe an object in a vacuum?
answers: text: in vacuo

question: What Latin adjective does atmospheric pressure come from?

question: What is the definition of atmospheric pressure?

question: What do physicists often discuss will occur in a certain atmospheric pressure?

question: What does the term partial atmospheric pressure refer to?

question: What latin term is used to describe an object under atmospheric pressure?
context: Vacuum is space void of matter. The word stems from the Latin adjective vacuus for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often discuss ideal test results that would occur in a perfect vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is lower than atmospheric pressure. The Latin term in vacuo is used to describe an object as being in what would otherwise be a vacuum.

qas: question: The Vacuum state is considered what?
answers: text: the ground state of matter.

question: A typical vacuum cleaner produces enough suction to do what to air pressure?
answers: text: reduce air pressure by around 20%

question: The quality of a partial vacuum refers to what?
answers: text: how closely it approaches a perfect vacuum

question: Outer space has a high quality vacuum with what equivalent?
answers: text: a few hydrogen atoms per cubic meter

question: If all matter is removed from a vacuum, would it be empty space?
answers: text: it would still not be "empty"

question: What does a few hydrogen atoms per cubic meter reduce air pressure by?

question: What does the quality of dark energy refer to?

question: What does lower amounts of dark matter mean?

question: In what century was dark matter discovered?

question: What does dark matter usually operate below in space?
context: The quality of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%. Much higher-quality vacuums are possible. Ultra-high vacuum chambers, common in chemistry, physics, and engineering, operate below one trillionth (10−12) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm3. Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average. According to modern understanding, even if all matter could be removed from a volume, it would still not be "empty" due to vacuum fluctuations, dark energy, transiting gamma rays, cosmic rays, neutrinos, and other phenomena in quantum physics. In the electromagnetism in the 19th century, vacuum was thought to be filled with a medium called aether. In modern particle physics, the vacuum state is considered the ground state of matter.

qas: question: What did Aristotle believe about a void?
answers: text: no void could occur naturally,

question: What was historically disputed about vacuums?
answers: text: whether such a thing as a vacuum can exist.

question: What did something that was literally nothing at all,According to Plato, mean?
answers: text: cannot rightly be said to exist

question: Aristotle thought what would fill any rarity that might give rise to a void?
answers: text: denser surrounding material continuum

question: What did Greek philosophers believe could not occur naturally?

question: What language was spoken by Plato?

question: What did Aristotle believe were the fundamental elements of understanding physics?

question: What can an atom not be understood by according to Greek philosophers?

question: What did Ancient Greek philosophers believe atoms could not do?
context: Historically, there has been much dispute over whether such a thing as a vacuum can exist. Ancient Greek philosophers debated the existence of a vacuum, or void, in the context of atomism, which posited void and atom as the fundamental explanatory elements of physics. Following Plato, even the abstract concept of a featureless void faced considerable skepticism: it could not be apprehended by the senses, it could not, itself, provide additional explanatory power beyond the physical volume with which it was commensurate and, by definition, it was quite literally nothing at all, which cannot rightly be said to exist. Aristotle believed that no void could occur naturally, because the denser surrounding material continuum would immediately fill any incipient rarity that might give rise to a void.

qas: question: In what century did believes start to move away from Aristotle's idea regarding a void?
answers: text: 14th century

question: What thought process was used in the beginning belief of the existence of vacuums?
answers: text: Stoic physics

question: What belief regarding a cosmic void was accepted by most in the 17th century?
answers: text: a supernatural void beyond the confines of the cosmos itself

question: Roger Bacon,Walter Burley and Blasius of Parma were from what century?
answers: text: 13th and 14th

question: What book was written by Lucretius?

question: How many arguments against the void did Lucretius give in his Physics, book IV?

question: In what year did Aristotle first study physics?

question: What did Lucretuis try to unsuccessfully create in the 14th century?

question: What belief about a void was accepted by most in the first cenury AD?
context: In his Physics, book IV, Aristotle offered numerous arguments against the void: for example, that motion through a medium which offered no impediment could continue ad infinitum, there being no reason that something would come to rest anywhere in particular. Although Lucretius argued for the existence of vacuum in the first century BC and Hero of Alexandria tried unsuccessfully to create an artificial vacuum in the first century AD, it was European scholars such as Roger Bacon, Blasius of Parma and Walter Burley in the 13th and 14th century who focused considerable attention on these issues. Eventually following Stoic physics in this instance, scholars from the 14th century onward increasingly departed from the Aristotelian perspective in favor of a supernatural void beyond the confines of the cosmos itself, a conclusion widely acknowledged by the 17th century, which helped to segregate natural and theological concerns.

qas: question: What does Rapid decompression do to the lungs?
answers: text: rupture of the delicate alveoli

question: What causes barotrauma?
answers: text: rapid decompression

question: What amount of pressure drop can kill you if it occurs suddenly?
answers: text: 13 kPa (100 Torr),

question: What does acceleration of oxygen consumption do?
answers: text: hypoxia

question: rapid decompression is more dangerous than what?
answers: text: vacuum exposure

question: What can tissues seeping blood be more dangerous than?

question: What does increasing oxygen consumption do to the lungs?

question: Venting through the windpipe may end up rupturing eardrums and what?

question: What will seep out of the windpipe if you hold your breath?

question: What is venting through the windpipe also called?
context: Rapid decompression can be much more dangerous than vacuum exposure itself. Even if the victim does not hold his or her breath, venting through the windpipe may be too slow to prevent the fatal rupture of the delicate alveoli of the lungs. Eardrums and sinuses may be ruptured by rapid decompression, soft tissues may bruise and seep blood, and the stress of shock will accelerate oxygen consumption leading to hypoxia. Injuries caused by rapid decompression are called barotrauma. A pressure drop of 13 kPa (100 Torr), which produces no symptoms if it is gradual, may be fatal if it occurs suddenly.

qas: question: What did Descartes believe about vacuums in nature?
answers: text: that a vacuum does not occur in nature

question: Whose work with metaphysics would come to define the notion of empty space?
answers: text: Descartes

question: What philosophy combined with Descartes to push quantum activity in the 20th century?
answers: text: Cartesian mechanical philosophy

question: What dichotomy did Descartes center his theory around?

question: What position did Plato agree with?

question: Where did Plato believe a vaccuum did not occur?

question: What philosophy was behind Plato's understanding of a vacuum?

question: What did Plato's discoveries about atomism come to define about empty space?
context: Almost two thousand years after Plato, René Descartes also proposed a geometrically based alternative theory of atomism, without the problematic nothing–everything dichotomy of void and atom. Although Descartes agreed with the contemporary position, that a vacuum does not occur in nature, the success of his namesake coordinate system and more implicitly, the spatial–corporeal component of his metaphysics would come to define the philosophically modern notion of empty space as a quantified extension of volume. By the ancient definition however, directional information and magnitude were conceptually distinct. With the acquiescence of Cartesian mechanical philosophy to the "brute fact" of action at a distance, and at length, its successful reification by force fields and ever more sophisticated geometric structure, the anachronism of empty space widened until "a seething ferment" of quantum activity in the 20th century filled the vacuum with a virtual pleroma.

qas: question: An infinite sea of particles with negative energy  was a model propesed by whom?
answers: text: Paul Dirac

question: What year was the Dirac sea modeled?
answers: text: 1930

question: When werer virtual particles confirmed?
answers: text: late 20th century

question: What year was the uncertainty principle formed?
answers: text: 1927,

question: What theorized that time and energy can be measured?
answers: text: Werner Heisenberg's uncertainty principle

question: What kind of energy did Werner Heisenberg believe a vacuum held?

question: What did Heisenberg call the particles with negative energy inside a vacuum?

question: What did Heisenberg predict the existence of in 1930?

question: How long did it take for the uncertainty principle by Dirac to be confirmed?

question: What in the late 20th century did Dirac theorize can be measured?
context: In 1930, Paul Dirac proposed a model of the vacuum as an infinite sea of particles possessing negative energy, called the Dirac sea. This theory helped refine the predictions of his earlier formulated Dirac equation, and successfully predicted the existence of the positron, confirmed two years later. Werner Heisenberg's uncertainty principle formulated in 1927, predict a fundamental limit within which instantaneous position and momentum, or energy and time can be measured. This has far reaching consequences on the "emptiness" of space between particles. In the late 20th century, so-called virtual particles that arise spontaneously from empty space were confirmed.

qas: question: what is a perfect example of a filled vacuum showing a curvature?
answers: text: The black hole

question: Who's equations  helped to imply vanishing of the Ricci tensor?
answers: text: Einstein

question: what produces curvature in a vacuum?
answers: text: tidal forces and gravitational waves

question: What has no electric charge?
answers: text: black hole

question: What kind of electric charge does a vanishing stress-energy tensor have?

question: What is a black hole a part of?

question: What field around the Earth was discovered by Einstein?

question: Tidal forces and gravitational waves can produce zero what?

question: What is the shape of a gravitational field?
context: In general relativity, a vanishing stress-energy tensor implies, through Einstein field equations, the vanishing of all the components of the Ricci tensor. Vacuum does not mean that the curvature of space-time is necessarily flat: the gravitational field can still produce curvature in a vacuum in the form of tidal forces and gravitational waves (technically, these phenomena are the components of the Weyl tensor). The black hole (with zero electric charge) is an elegant example of a region completely "filled" with vacuum, but still showing a strong curvature.

qas: question: Where do most satellites operate?
answers: text: low Earth orbit

question: What system could possibly be used for interplanetary travel?
answers: text: solar sails

question: why do satellites need to fire engines every few day to keep orbit?
answers: text: atmospheric density

question: above what line location in outer space to satellites orbit?
answers: text: Kármán line

question: How often does Earth's orbit position change?

question: What are satellites eroded by?

question: What are satellites too large for their engines to be affected by?

question: How long is the Karman line?

question: What have satellite engines been suggested to be used for?
context: But although it meets the definition of outer space, the atmospheric density within the first few hundred kilometers above the Kármán line is still sufficient to produce significant drag on satellites. Most artificial satellites operate in this region called low Earth orbit and must fire their engines every few days to maintain orbit.[citation needed] The drag here is low enough that it could theoretically be overcome by radiation pressure on solar sails, a proposed propulsion system for interplanetary travel.[citation needed] Planets are too massive for their trajectories to be significantly affected by these forces, although their atmospheres are eroded by the solar winds.

qas: question: Al-Farabi concluded a perfect vacuum was incoherent using what?
answers: text: handheld plungers in water.

question: Ibn al-Haytham used geometry to demonstrate  what?
answers: text: place (al-makan) is the imagined three-dimensional void between the inner surfaces of a containing body

question: who stated that there was no evidence to rule out a vacuum?
answers: text: Abū Rayhān al-Bīrūnī

question: what did Al-Farabi say expanded to fill available space
answers: text: air's volume

question: What type of pump appeared in the 15th century?
answers: text: suction pump

question: What was Aristotle able to demonstrate about place?

question: In what century did Aristotle develop the suction pump?

question: What did Aristotle investigate to test the existence of a vacuum?

question: What did Aristotle suggest about the concept of a perfect vacuum after his experiment?

question: What did Aristotle state there was no evidence to rule out?
context: In the medieval Middle Eastern world, the physicist and Islamic scholar, Al-Farabi (Alpharabius, 872–950), conducted a small experiment concerning the existence of vacuum, in which he investigated handheld plungers in water.[unreliable source?] He concluded that air's volume can expand to fill available space, and he suggested that the concept of perfect vacuum was incoherent. However, according to Nader El-Bizri, the physicist Ibn al-Haytham (Alhazen, 965–1039) and the Mu'tazili theologians disagreed with Aristotle and Al-Farabi, and they supported the existence of a void. Using geometry, Ibn al-Haytham mathematically demonstrated that place (al-makan) is the imagined three-dimensional void between the inner surfaces of a containing body. According to Ahmad Dallal, Abū Rayhān al-Bīrūnī also states that "there is no observable evidence that rules out the possibility of vacuum". The suction pump later appeared in Europe from the 15th century.

qas: question: Who required no restrictions regarding God's power?
answers: text: Bishop Etienne Tempier

question: When did Buridan state that teams of ten horses could not open a bellow with a sealed port?
answers: text: 14th century

question: the 1277 Paris Condemnations led to what conclusion?
answers: text: God could create a vacuum if he so wished.

question: What was a common belief about vacuums and nature?
answers: text: nature abhorred a vacuum

question: what was the belief that nature abhorred a vaccuum called?
answers: text: horror vacui

question: What did Bishop Etienne Tempier believe prevented a vacuum from forming?

question: What was the commonly held view in the medieval period that God could not create a vacuum called?

question: What point of view regarding God became popular in the 14th century?

question: According to Walter Burley in the 14th century, what could teams of ten horses not pull open?

question: What did Walter Burley require there be no restrictions on in the 14th century?
context: Medieval thought experiments into the idea of a vacuum considered whether a vacuum was present, if only for an instant, between two flat plates when they were rapidly separated. There was much discussion of whether the air moved in quickly enough as the plates were separated, or, as Walter Burley postulated, whether a 'celestial agent' prevented the vacuum arising. The commonly held view that nature abhorred a vacuum was called horror vacui. Speculation that even God could not create a vacuum if he wanted to was shut down[clarification needed] by the 1277 Paris condemnations of Bishop Etienne Tempier, which required there to be no restrictions on the powers of God, which led to the conclusion that God could create a vacuum if he so wished. Jean Buridan reported in the 14th century that teams of ten horses could not pull open bellows when the port was sealed.

qas: question: What was the vacuum created by the mercury displacement pump?
answers: text: partial vacuum of about 10 Pa (0.1 Torr).

question: What year was the Toepler Pump invented?
answers: text: 1850

question: What was first invented by Otto von Guericke ?
answers: text: vacuum pump

question: Who conducted the Magdeburg experiment?
answers: text: Otto von Guericke

question: What was made visible at a partial vacuum of 10 Pa?
answers: text: A number of electrical properties

question: What was invented by Robert Boyle in 1654?

question: What was the famous experiment called that Robert Boyle conducted?

question: What type of vacuum did Robert Boyle achieve in 1855?

question: What did Heinrich Geissler help Otto von Guericke further develop?

question: In what year did Otto von Guericke invent the mercury displacement pump?
context: In 1654, Otto von Guericke invented the first vacuum pump and conducted his famous Magdeburg hemispheres experiment, showing that teams of horses could not separate two hemispheres from which the air had been partially evacuated. Robert Boyle improved Guericke's design and with the help of Robert Hooke further developed vacuum pump technology. Thereafter, research into the partial vacuum lapsed until 1850 when August Toepler invented the Toepler Pump and Heinrich Geissler invented the mercury displacement pump in 1855, achieving a partial vacuum of about 10 Pa (0.1 Torr). A number of electrical properties become observable at this vacuum level, which renewed interest in further research.

qas: question: What was originally believed the heavens were filled with?
answers: text: aether

question: Why were experiments done on luminiferous aether in the 19 Century?
answers: text: "While the interstellar absorbing medium may be simply the ether, [it] is characteris

question: Who stated that the character of a gas and free molecule were in ether?
answers: text: Henry Pickering

question: Where are the highest amounts of naturally occurring partial vacuums?
answers: text: outer space

question: What was ether originally thought to be made of?
answers: text: rigid indestructible material

question: What did Issac Newton believe existed in space in 1912?

question: What were molecules originally thought to be made of?

question: What is another name for mythology?

question: Where did the ideas about the properties of molecules come from?

question: What did experiments with molecules attempt to detect on the Earths orbit?
context: While outer space provides the most rarefied example of a naturally occurring partial vacuum, the heavens were originally thought to be seamlessly filled by a rigid indestructible material called aether. Borrowing somewhat from the pneuma of Stoic physics, aether came to be regarded as the rarefied air from which it took its name, (see Aether (mythology)). Early theories of light posited a ubiquitous terrestrial and celestial medium through which light propagated. Additionally, the concept informed Isaac Newton's explanations of both refraction and of radiant heat. 19th century experiments into this luminiferous aether attempted to detect a minute drag on the Earth's orbit. While the Earth does, in fact, move through a relatively dense medium in comparison to that of interstellar space, the drag is so minuscule that it could not be detected. In 1912, astronomer Henry Pickering commented: "While the interstellar absorbing medium may be simply the ether, [it] is characteristic of a gas, and free gaseous molecules are certainly there".

qas: question: What indicated the quality of a vacuum?
answers: text: amount of matter remaining in the system

question: How is vacuum generally measured?
answers: text: its absolute pressure

question: What does the MFP of residual gases show?
answers: text: average distance that molecules will travel between collisions with each other.

question: What is particle gas dynamics?
answers: text: study of fluid flows

question: What indicates the quality of residual gases?

question: How much matter is left in residual gases?

question: How are residual gases measured?

question: What other factors are necessary to measure residual gases?

question: What is the study of residual gases in a spacecraft called?
context: The quality of a vacuum is indicated by the amount of matter remaining in the system, so that a high quality vacuum is one with very little matter left in it. Vacuum is primarily measured by its absolute pressure, but a complete characterization requires further parameters, such as temperature and chemical composition. One of the most important parameters is the mean free path (MFP) of residual gases, which indicates the average distance that molecules will travel between collisions with each other. As the gas density decreases, the MFP increases, and when the MFP is longer than the chamber, pump, spacecraft, or other objects present, the continuum assumptions of fluid mechanics do not apply. This vacuum state is called high vacuum, and the study of fluid flows in this regime is called particle gas dynamics. The MFP of air at atmospheric pressure is very short, 70 nm, but at 100 mPa (~6997100000000000000♠1×10−3 Torr) the MFP of room temperature air is roughly 100 mm, which is on the order of everyday objects such as vacuum tubes. The Crookes radiometer turns when the MFP is larger than the size of the vanes.

qas: question: Absolute pressure  being equal to current atmospheric pressure means what?
answers: text: "Below atmospheric"

question: What is a torr equal to?
answers: text: displacement of a millimeter of mercury

question: What is another often used options to measure vacuum?
answers: text: barometric scale

question: During what years was mercury commonly in use?

question: What is the barometric scale equal to?

question: What element did Torricelli discover in 1608?

question: How many pascals does the barometric scale equal?

question: What is another way to measure the state of being below atmospheric?
context: The SI unit of pressure is the pascal (symbol Pa), but vacuum is often measured in torrs, named for Torricelli, an early Italian physicist (1608–1647). A torr is equal to the displacement of a millimeter of mercury (mmHg) in a manometer with 1 torr equaling 133.3223684 pascals above absolute zero pressure. Vacuum is often also measured on the barometric scale or as a percentage of atmospheric pressure in bars or atmospheres. Low vacuum is often measured in millimeters of mercury (mmHg) or pascals (Pa) below standard atmospheric pressure. "Below atmospheric" means that the absolute pressure is equal to the current atmospheric pressure.

qas: question: Why is mercury the better option for liquid used in a Hydrostatic gauge?
answers: text: its high density and low vapour pressure

question: What is a vertical column of liquid in a tube which has different pressures at each end called?
answers: text: Hydrostatic gauges

question: What is a hydrostatic gauge used for?
answers: text: measure pressures ranging from 1 torr (100 Pa) to above atmospheric

question: Why is the McLeod gauge special?
answers: text: can measure vacuums as high as 10−6 torr

question: An indirect measurement of pressure is most often calibrated by what?
answers: text: McLeod gauge

question: What is the level of mercury in the air calibrated by?

question: What is the density level of mercury in the air?

question: What is used to measure mercury in the air?

question: What is the lowest amount of mercury that can be measured in the air?

question: What measurements are used to measure mercury in the air?
context: Hydrostatic gauges (such as the mercury column manometer) consist of a vertical column of liquid in a tube whose ends are exposed to different pressures. The column will rise or fall until its weight is in equilibrium with the pressure differential between the two ends of the tube. The simplest design is a closed-end U-shaped tube, one side of which is connected to the region of interest. Any fluid can be used, but mercury is preferred for its high density and low vapour pressure. Simple hydrostatic gauges can measure pressures ranging from 1 torr (100 Pa) to above atmospheric. An important variation is the McLeod gauge which isolates a known volume of vacuum and compresses it to multiply the height variation of the liquid column. The McLeod gauge can measure vacuums as high as 10−6 torr (0.1 mPa), which is the lowest direct measurement of pressure that is possible with current technology. Other vacuum gauges can measure lower pressures, but only indirectly by measurement of other pressure-controlled properties. These indirect measurements must be calibrated via a direct measurement, most commonly a McLeod gauge.

qas: question: The fact that gases ability to conduct heat decreases with pressure is used by what form of measurement?
answers: text: Thermal conductivity gauges

question: How is the wire filament in a Thermal conductivity gauge heated?
answers: text: by running current through it

question: What is a Pirani gauge sensitive to?
answers: text: chemical composition of the gases being measured

question: What is a RTD used for on a Thermal Conductivity gauge?
answers: text: to measure the temperature of the filament

question: A Pirani gauge is accurate within what ranges?
answers: text: 10 torr to 10−3 torr

question: How does plantinums ability to conduct heat decrease?

question: What kind of filament does the RTD use?

question: How do thermal conductivity gauges use a single platinum filament as?

question: How quickly does a filament lose heat?

question: Pressure is sensitive to the heated element of what?
context: Thermal conductivity gauges rely on the fact that the ability of a gas to conduct heat decreases with pressure. In this type of gauge, a wire filament is heated by running current through it. A thermocouple or Resistance Temperature Detector (RTD) can then be used to measure the temperature of the filament. This temperature is dependent on the rate at which the filament loses heat to the surrounding gas, and therefore on the thermal conductivity. A common variant is the Pirani gauge which uses a single platinum filament as both the heated element and RTD. These gauges are accurate from 10 torr to 10−3 torr, but they are sensitive to the chemical composition of the gases being measured.

qas: question: What are the two types of Ion gauges?
answers: text: hot cathode and cold cathode.

question: What affects the number of ions in a gauge?
answers: text: the pressure in the gauge

question: What gauge is accurate from 10-2 torr to 10-9 torr?
answers: text: Cold cathode gauges

question: What must be used for accurate measurement on the composition of gases at a high vacuums?
answers: text: mass spectrometer must be used in conjunction with the ionization gauge

question: Why does a mass spectrometer need to be used with gauge to be accurate at high vacuum gas measurement?
answers: text: composition of gases at high vacuums will usually be unpredictable

question: What are the two types of mass spectrometers?

question: In the hot cathode version what does corrosion produce?

question: What is ionized when electrodes travel through a mass spectrometer?

question: What is the accuracy of a mass spectrometer?

question: What is the nature of electrically heated filaments at high vacuums?
context: Ion gauges are used in ultrahigh vacuum. They come in two types: hot cathode and cold cathode. In the hot cathode version an electrically heated filament produces an electron beam. The electrons travel through the gauge and ionize gas molecules around them. The resulting ions are collected at a negative electrode. The current depends on the number of ions, which depends on the pressure in the gauge. Hot cathode gauges are accurate from 10−3 torr to 10−10 torr. The principle behind cold cathode version is the same, except that electrons are produced in a discharge created by a high voltage electrical discharge. Cold cathode gauges are accurate from 10−2 torr to 10−9 torr. Ionization gauge calibration is very sensitive to construction geometry, chemical composition of gases being measured, corrosion and surface deposits. Their calibration can be invalidated by activation at atmospheric pressure or low vacuum. The composition of gases at high vacuums will usually be unpredictable, so a mass spectrometer must be used in conjunction with the ionization gauge for accurate measurement.

qas: question: density of oxygen like that of sea-level atmosphere is needed to do what?
answers: text: sustain life at pressures much lower than atmospheric,

question: What is the lowest altitude where acclimatization or a suit is not needed to prevent sickness in humans?
answers: text: of up to 3 km

question: What do colder air temperatures found at altitudes above 19km compensate for?

question: What is needed at altitudes of up to 3km to prevent altitiude sickness?

question: What do cold or oxygen-rich atmospheres usuall cause?

question: How much pure oxygen is in the atmosphere?

question: When people are acclimated to the altitude, gas embolisms and what can happen?
context: Cold or oxygen-rich atmospheres can sustain life at pressures much lower than atmospheric, as long as the density of oxygen is similar to that of standard sea-level atmosphere. The colder air temperatures found at altitudes of up to 3 km generally compensate for the lower pressures there. Above this altitude, oxygen enrichment is necessary to prevent altitude sickness in humans that did not undergo prior acclimatization, and spacesuits are necessary to prevent ebullism above 19 km. Most spacesuits use only 20 kPa (150 Torr) of pure oxygen. This pressure is high enough to prevent ebullism, but decompression sickness and gas embolisms can still occur if decompression rates are not managed.

qas: question: When will a person or animal lose consciousness  when exposed to a vacuum?
answers: text: after a few seconds

question: A shuttle astronauts prevents ebullism at 2 kPa with what item?
answers: text: the Crew Altitude Protection Suit (CAPS)

question: What is the forming of gas bubbles in body fluids at a lowered pressure called?
answers: text: ebullism

question: What prevents body rupture at low altitude when human body is bloated by gas bubbles?
answers: text: tissues are elastic and porous

question: At what temperature does frost usually occur in space?

question: When exposed to frost who will die from ebullism within minutes?

question: What will frost cause in body fluids at reduced pressures?

question: What can a person wear to prevent frost on the skin?

question: What does a CAPS suit prevent frost at pressures as low as?
context: Humans and animals exposed to vacuum will lose consciousness after a few seconds and die of hypoxia within minutes, but the symptoms are not nearly as graphic as commonly depicted in media and popular culture. The reduction in pressure lowers the temperature at which blood and other body fluids boil, but the elastic pressure of blood vessels ensures that this boiling point remains above the internal body temperature of 37 °C. Although the blood will not boil, the formation of gas bubbles in bodily fluids at reduced pressures, known as ebullism, is still a concern. The gas may bloat the body to twice its normal size and slow circulation, but tissues are elastic and porous enough to prevent rupture. Swelling and ebullism can be restrained by containment in a flight suit. Shuttle astronauts wore a fitted elastic garment called the Crew Altitude Protection Suit (CAPS) which prevents ebullism at pressures as low as 2 kPa (15 Torr). Rapid boiling will cool the skin and create frost, particularly in the mouth, but this is not a significant hazard.

qas: question: What can boil away in extreme vaccum exposure?
answers: text: Some oils and greases

question: How should the grain direct of metallic flanges run to flange faces?
answers: text: parallel

question: What are 2 metals that can be absorbed in an ultra high vacuum system?
answers: text: stainless steel or titanium

question: What becomes a concern in an ultra high vacuum system regarding aluminum or palladium?
answers: text: water absorption

question: What will boil off when aluminum absorbs water?

question: How should palladium be placed when it has oil on it?

question: What are two metals that can be absorbed in an metallic flange?

question: In what area will water boil off?

question: What will grease usually run parallel to?
context: In ultra high vacuum systems, some very "odd" leakage paths and outgassing sources must be considered. The water absorption of aluminium and palladium becomes an unacceptable source of outgassing, and even the adsorptivity of hard metals such as stainless steel or titanium must be considered. Some oils and greases will boil off in extreme vacuums. The permeability of the metallic chamber walls may have to be considered, and the grain direction of the metallic flanges should be parallel to the flange face.

qas: question: The state with the lowest possible energy in quantum mechanics defines what ?
answers: text: vacuum

question: A vacuum state with no matter particles or photons is called what?
answers: text: QED

question: why is a QED vacuum impossible to achieve ?
answers: text: impossible to eliminate all the blackbody photons

question: What is a QCD?
answers: text: vacuum of quantum chromodynamics,

question: What are blackbody photons in quantum mechanics?

question: What do blackbody photons with no matter particles or photons form?

question: Why is a blackbody field impossible to achieve?

question: What would you need to remove to create a blackbody field?

question: What is a blackbody photon referred to in quantum mechanics?
context: In quantum mechanics and quantum field theory, the vacuum is defined as the state (that is, the solution to the equations of the theory) with the lowest possible energy (the ground state of the Hilbert space). In quantum electrodynamics this vacuum is referred to as 'QED vacuum' to distinguish it from the vacuum of quantum chromodynamics, denoted as QCD vacuum. QED vacuum is a state with no matter particles (hence the name), and also no photons. As described above, this state is impossible to achieve experimentally. (Even if every matter particle could somehow be removed from a volume, it would be impossible to eliminate all the blackbody photons.) Nonetheless, it provides a good model for realizable vacuum, and agrees with a number of experimental observations as described next.

qas: question: When are electric and magnetic fields with zero average values, but their variances are not at zero?
answers: text: In QED vacuum

question: What is a verified effect of vacuum fluctuation?
answers: text: spontaneous emission

question: what is  vacuum fluctuation?
answers: text: virtual particles that hop into and out of existence

question: Finite energy in a QED is called what?
answers: text: vacuum energy

question: What modifies can Coulomb's Law in a vacuum?
answers: text: vacuum near an electric charge

question: What part of quantum field theory are electric and magnetic fields?

question: What kind of properties does Coulomb's law have?

question: What values does vacuum energy have under Coulomb's law?

question: What are the variances of vacuum energy according to Coulomb's law?

question: What do particles defined in Colombo's law do?
context: QED vacuum has interesting and complex properties. In QED vacuum, the electric and magnetic fields have zero average values, but their variances are not zero. As a result, QED vacuum contains vacuum fluctuations (virtual particles that hop into and out of existence), and a finite energy called vacuum energy. Vacuum fluctuations are an essential and ubiquitous part of quantum field theory. Some experimentally verified effects of vacuum fluctuations include spontaneous emission and the Lamb shift. Coulomb's law and the electric potential in vacuum near an electric charge are modified.

qas: question: `Why does thermosphere past the Karman line vary so greatly?
answers: text: due to space weather

question: What is commonly known as the boundary of outer space?
answers: text: the Kármán line

question: What do Astrophysicists use to describe outer space beyond the karman line?
answers: text: number density

question: What is more significant than isotropic gas pressure past the Karman line?
answers: text: radiation pressure from the Sun and the dynamic pressure of the solar winds

question: What is commonly known as the boundary of the Sun?

question: What do astrophysicists use to describe sun radiation?

question: In what units do astrophysicists use to describe sun radiation?

question: What does the Sun's atmospheric pressure drop to at 100 km of altitude?

question: What becomes insidgnificant when it reaches the surface of the moon?
context: Stars, planets, and moons keep their atmospheres by gravitational attraction, and as such, atmospheres have no clearly delineated boundary: the density of atmospheric gas simply decreases with distance from the object. The Earth's atmospheric pressure drops to about 6998320000000000000♠3.2×10−2 Pa at 100 kilometres (62 mi) of altitude, the Kármán line, which is a common definition of the boundary with outer space. Beyond this line, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from the Sun and the dynamic pressure of the solar winds, so the definition of pressure becomes difficult to interpret. The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather. Astrophysicists prefer to use number density to describe these environments, in units of particles per cubic centimetre.

qas: question: What was the object to use first in widespread manner process of vacuum?
answers: text: incandescent light bulb

question: What is produced by a vacuum and used in electron beam welding and vacuum frying?
answers: text: chemical inertness

question: Hight to ultra-high vacuums removes what obstruction?
answers: text: obstruction of air,

question: How does freeze drying, distillation and metallurgy benefit from a deep vacuum?
answers: text: Deep vacuum lowers the boiling point of liquids and promotes low temperature outgassing

question: What are two things made possible by the electrical properties of vacuum?
answers: text: electron microscopes and vacuum tubes

question: What three things are light bulbs useful for?

question: What are lightbulbs used to study?

question: What do lightbulbs allow particle beams to do without contamination?

question: What method of preserving food is dependant on using lightbulbs?

question: What are lightbulbs able to lower the boiling point of?
context: Vacuum is useful in a variety of processes and devices. Its first widespread use was in the incandescent light bulb to protect the filament from chemical degradation. The chemical inertness produced by a vacuum is also useful for electron beam welding, cold welding, vacuum packing and vacuum frying. Ultra-high vacuum is used in the study of atomically clean substrates, as only a very good vacuum preserves atomic-scale clean surfaces for a reasonably long time (on the order of minutes to days). High to ultra-high vacuum removes the obstruction of air, allowing particle beams to deposit or remove materials without contamination. This is the principle behind chemical vapor deposition, physical vapor deposition, and dry etching which are essential to the fabrication of semiconductors and optical coatings, and to surface science. The reduction of convection provides the thermal insulation of thermos bottles. Deep vacuum lowers the boiling point of liquids and promotes low temperature outgassing which is used in freeze drying, adhesive preparation, distillation, metallurgy, and process purging. The electrical properties of vacuum make electron microscopes and vacuum tubes possible, including cathode ray tubes. The elimination of air friction is useful for flywheel energy storage and ultracentrifuges.

qas: question: What provides power assistance for auto brakes?
answers: text: vacuum servo

question: What are two available sources of vacuum on a moving airplane?
answers: text: engine and an external venturi

question: Why are the Attitude indicator and heading indicator vacuum-powered?
answers: text: protection against loss of all (electrically powered) instruments,

question: What does a manifold vacuum do on a car?
answers: text: drive accessories

question: What no longer used accessories were powered by vacuum?
answers: text: vacuum-driven windscreen wipers and Autovac fuel pumps

question: What do electrical systems use within a vacuum?

question: What can electrical systems be used to drive on automobiles?

question: What are electrical systems used to provide power assistance for on a car?

question: What two instruments do electrical systems usually power on some aircraft?

question: Why are the AI and the HI usually powered by autovac fuel pumps?
context: Manifold vacuum can be used to drive accessories on automobiles. The best-known application is the vacuum servo, used to provide power assistance for the brakes. Obsolete applications include vacuum-driven windscreen wipers and Autovac fuel pumps. Some aircraft instruments (Attitude Indicator (AI) and the Heading Indicator (HI)) are typically vacuum-powered, as protection against loss of all (electrically powered) instruments, since early aircraft often did not have electrical systems, and since there are two readily available sources of vacuum on a moving aircraft—the engine and an external venturi. Vacuum induction melting uses electromagnetic induction within a vacuum.

qas: question: what is evaporation and sublimation in a vacuum?
answers: text: outgassing

question: When does outgassing become important in all solid or liquid materials?
answers: text: vacuum pressure falls below this vapour pressure

question: Why can outgassing products ruin a space mission?
answers: text: obscure optical instruments

question: What does liquid have the same effect as in a telescope?

question: What can solar cells limit the achievement of?

question: On what kind of surfaces can space missions happen?

question: What is the cost of a telescope for a space mission?

question: What is a solid touching a cold surface called?
context: Evaporation and sublimation into a vacuum is called outgassing. All materials, solid or liquid, have a small vapour pressure, and their outgassing becomes important when the vacuum pressure falls below this vapour pressure. In man-made systems, outgassing has the same effect as a leak and can limit the achievable vacuum. Outgassing products may condense on nearby colder surfaces, which can be troublesome if they obscure optical instruments or react with other materials. This is of great concern to space missions, where an obscured telescope or solar cell can ruin an expensive mission.

qas: question: Repeatedly closing off a compartment of a vacuum allows what?
answers: text: continue evacuating a chamber indefinitely without requiring infinite growth

question: How is a vacuum created inside of a manual water pump?
answers: text: a mechanism expands a small sealed cavity

question: Why is fluid in a manual pump pushed into the pumps cavity when a small sealed cavity is expanded?
answers: text: Because of the pressure differential

question: What are pumps based off principle of sealed compartment pulling,pushing and expanding called?
answers: text: displacement pumps

question: What does repeatedly putting water into the atmosphere manually allow?

question: How is a vacuum created in the atmosphere?

question: What kind of growth happens when fluid enters the atmosphere?

question: What expands outside the pump?

question: What size is the vacuum in the pump?
context: To continue evacuating a chamber indefinitely without requiring infinite growth, a compartment of the vacuum can be repeatedly closed off, exhausted, and expanded again. This is the principle behind positive displacement pumps, like the manual water pump for example. Inside the pump, a mechanism expands a small sealed cavity to create a vacuum. Because of the pressure differential, some fluid from the chamber (or the well, in our example) is pushed into the pump's small cavity. The pump's cavity is then sealed from the chamber, opened to the atmosphere, and squeezed back to a minute size.

qas: question: What pump can capture gases in a solid or absorbed state?
answers: text: Entrapment pumps

question: Entrapment pumps often work without seals, moving parts and what else?
answers: text: no vibration.

question: What pump has a higher quality vacuum than a positive displacement pump?
answers: text: Momentum transfer pumps

question: What can positive displacement pumps achieve more than entrapment pumps?

question: What can momentum transfer pumps capture?

question: Dynamic pumps often work without moving parts, seals and what?

question: What are entrapment pumps usually considered above all of the others?

question: What other pump do entrapment pumps have similarities to?
context: The above explanation is merely a simple introduction to vacuum pumping, and is not representative of the entire range of pumps in use. Many variations of the positive displacement pump have been developed, and many other pump designs rely on fundamentally different principles. Momentum transfer pumps, which bear some similarities to dynamic pumps used at higher pressures, can achieve much higher quality vacuums than positive displacement pumps. Entrapment pumps can capture gases in a solid or absorbed state, often with no moving parts, no seals and no vibration. None of these pumps are universal; each type has important performance limitations. They all share a difficulty in pumping low molecular weight gases, especially hydrogen, helium, and neon.

qas: question: When multiple pumps are connected in series to produce higher vacuum it is called what?
answers: text: stages

question: The choice of seals, or chamber geometry ,for example impact a pump. Together these are options are called what?
answers: text: vacuum technique

question: What are two other relevant characteristics of a pumping system along with final pressure?
answers: text: oil contamination, vibration

question: How can chamber geometry be connected?

question: What can oil contamination be dependent on instead of pump nature?

question: How do leakage rates usually happen?

question: What do certain gases usually help a pump achieve?

question: What are two other characteristics of a seal?
context: The lowest pressure that can be attained in a system is also dependent on many things other than the nature of the pumps. Multiple pumps may be connected in series, called stages, to achieve higher vacuums. The choice of seals, chamber geometry, materials, and pump-down procedures will all have an impact. Collectively, these are called vacuum technique. And sometimes, the final pressure is not the only relevant characteristic. Pumping systems differ in oil contamination, vibration, preferential pumping of certain gases, pump-down speeds, intermittent duty cycle, reliability, or tolerance to high leakage rates.

qas: question: What can be measured in the atmosphere?

question: What can a container spread and dilute?

question: What does fluid push into the lungs?

question: What moves high pressure in the atmosphere?

question: What can be used in a chest cavity during surgery?
context: Fluids cannot generally be pulled, so a vacuum cannot be created by suction. Suction can spread and dilute a vacuum by letting a higher pressure push fluids into it, but the vacuum has to be created first before suction can occur. The easiest way to create an artificial vacuum is to expand the volume of a container. For example, the diaphragm muscle expands the chest cavity, which causes the volume of the lungs to increase. This expansion reduces the pressure and creates a partial vacuum, which is soon filled by air pushed in by atmospheric pressure.