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Maxwell's demon is an 1871 thought experiment by the Scottish physicist James Clerk Maxwell, meant to raise questions about the possibility of violating the second law of thermodynamics. Year 1871 ( MDCCCLXXI) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar (or a Common A thought experiment (from the German Gedankenexperiment) is a proposal for an Experiment that would test a Hypothesis or Theory Scotland ( Gaelic: Alba) is a Country in northwest Europethat occupies the northern third of the island of Great Britain. A physicist is a Scientist who studies or practices Physics. Physicists study a wide range of physical phenomena in many branches of physics spanning James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. The second law of Thermodynamics is an expression of the universal law of increasing Entropy, stating that the entropy of an Isolated system which

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Maxwell's thought experiment

The Second Law of Thermodynamics forbids (due to statistical improbability) that two bodies of equal temperature, when brought into contact with each other and isolated from the rest of the Universe, will evolve to a state in which one of the two has a significantly higher temperature than the other. The second law of Thermodynamics is an expression of the universal law of increasing Entropy, stating that the entropy of an Isolated system which Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The second law is also expressed as the assertion that in an isolated system, entropy never decreases. In the Natural sciences an isolated system, as contrasted with a open system, is a Physical system that does not interact with its Surroundings In Thermodynamics (a branch of Physics) entropy, symbolized by S, is a measure of the unavailability of a system ’s Energy

Maxwell conceived a "thought experiment" as a challenge to the second law. He described the experiment as follows:[1]:

. . . if we conceive of a being whose faculties are so sharpened that he can follow every molecule in its course, such a being, whose attributes are as essentially finite as our own, would be able to do what is impossible to us. For we have seen that molecules in a vessel full of air at uniform temperature are moving with velocities by no means uniform, though the mean velocity of any great number of them, arbitrarily selected, is almost exactly uniform. Now let us suppose that such a vessel is divided into two portions, A and B, by a division in which there is a small hole, and that a being, who can see the individual molecules, opens and closes this hole, so as to allow only the swifter molecules to pass from A to B, and only the slower molecules to pass from B to A. He will thus, without expenditure of work, raise the temperature of B and lower that of A, in contradiction to the second law of thermodynamics.

Schematic figure of Maxwell's demon
Schematic figure of Maxwell's demon

In other words, Maxwell imagines two containers, A and B. The containers are filled with the same gas at equal temperatures and placed next to each other. This page is about the physical properties of gas as a state of matter Observing the molecules on both sides, a little "demon" guards a trapdoor between the two containers. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by When a faster-than-average molecule from A flies towards the trapdoor, the demon opens it, and the molecule will fly from A to B. The average speed of the molecules in B will have increased while in A they will have slowed down on average. Speed is the rate of motion, or equivalently the rate of change in position often expressed as Distance d traveled per unit of Since average molecular speed corresponds to temperature, the temperature decreases in A and increases in B, contrary to the second law of thermodynamics.

Criticism and development

Maxwell's thought experiment has troubled physicists since he first published it.

Is Maxwell correct?
Could such a demon, as he describes it, actually violate the second law?

Several physicists have presented calculations that show that the second law of thermodynamics will not actually be violated, if a more complete analysis is made of the whole system including the demon. The second law of Thermodynamics is an expression of the universal law of increasing Entropy, stating that the entropy of an Isolated system which The essence of the physical argument is to show by calculation that any demon must "generate" more entropy segregating the molecules than it could ever eliminate by the method described. That is, it would take more effort to gauge the speed of the molecules and allow them to selectively pass through the opening between A and B than the amount of energy saved by the difference of temperature caused by this.

One of the most famous responses to this question was suggested in 1929 by Leó Szilárd and later by Léon Brillouin. Year 1929 ( MCMXXIX) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar. Leó Szilárd (Szilárd Leó February 11, 1898 – May 30, 1964) was an Hungarian - American Physicist who Léon Nicolas Brillouin ( August 7, 1889 &ndash December 1969 was a French physicist Szilárd pointed out that a real-life Maxwell's demon would need to have some means of measuring molecular speed, and that the act of acquiring information would require an expenditure of energy. The second law states that the total entropy of an isolated system must increase. The second law of Thermodynamics is an expression of the universal law of increasing Entropy, stating that the entropy of an Isolated system which Since the demon and the gas are interacting, we must consider the total entropy of the gas and the demon combined. The expenditure of energy by the demon will cause an increase in the entropy of the demon, which will be larger than the lowering of the entropy of the gas. For example, if the demon is checking molecular positions using a flashlight, the flashlight battery is a low-entropy device, a chemical reaction waiting to happen. As its energy is used up emitting photons (whose entropy must now be counted as well), the battery's chemical reaction will proceed and its entropy will increase, more than offsetting the decrease in the entropy of the gas.

Szilárd's insight was expanded upon in 1982 by Charles H. Bennett. Year 1982 ( MCMLXXXII) was a Common year starting on Friday (link displays the 1982 Gregorian calendar) Charles H Bennett is an IBM Fellow at IBM Research. Bennett's recent work at IBM has concentrated on a re-examination of the physical basis of information applying In 1960, Rolf Landauer realized that certain measurements need not increase thermodynamic entropy as long as they were thermodynamically reversible. Rolf Landauer (1927–1999 was an IBM Physicist who in 1961 demonstrated that when Information is lost in an Irreversible circuit, the For articles on other forms of reversibility including reversibility of microscopic dynamics see Reversibility (disambiguation. Due to the connection between thermodynamic entropy and information entropy, this also meant that the recorded measurement must not be erased. In other words, to determine what side of the gate a molecule must be on, the demon must store information about the state of the molecule. Bennett showed that, however well prepared, eventually the demon will run out of information storage space and must begin to erase the information it has previously gathered. Charles H Bennett is an IBM Fellow at IBM Research. Bennett's recent work at IBM has concentrated on a re-examination of the physical basis of information applying Erasing information is a thermodynamically irreversible process that increases the entropy of a system. [2]

Note that if the whole universe consisted of the demon and the container, and energy were needed to operate the gate, the only source of energy is letting heat flow from B to A. Now, the quantum of B to A heat flow is a single particle going from B to A. This restores entropy, because on average the single particles going from B to A are more energetic than the ones going from A to B.

The above argument can take another form if the door is modeled as a potential energy barrier. In order to raise the potential, work must be done, and that potential energy cliff should be higher than the kinetic energy of the particle going from A to B. Thus, the quantum of heat flow going from B to A should be more energetic than the incoming particle.

Put simply, no matter how it is done, both the act of the demon watching molecules and the act of opening and closing the trapdoor is by definition work and requires the expenditure of energy. In Physics, mechanical work is the amount of Energy transferred by a Force. These explanations, however, are inadequate as the concept of the demon is not stated and may work as described below.

Furthermore, John Earman and John Norton have argued that Szilard and Landauer's explanations of Maxwell's Demon begin by assuming that the second law of thermodynamics cannot be violated, thus rendering their proofs that Maxwell's Demon cannot violate the Second Law vacuous. John Earman (born 1942 is a philosopher of physics. He is currently a professor in the History and Philosophy of Science department at the University of Pittsburgh The second law of Thermodynamics is an expression of the universal law of increasing Entropy, stating that the entropy of an Isolated system which

Applications

Real-life versions of Maxwellian demons occur, but all such "real demons" have their entropy-lowering effects duly balanced by increase of entropy elsewhere.

Single-atom traps used by particle physicists allow an experimenter to control the state of individual quanta in a way similar to Maxwell's demon.

Molecular-sized mechanisms are no longer found only in biology; they are also the subject of the emerging field of nanotechnology. Nanotechnology, sometimes shortened to nanotech, refers to a field of Applied science whose theme is the control of matter on an Atomic and Molecular

A large-scale, commercially-available pneumatic device, called a Ranque-Hilsch vortex tube separates hot and cold air. For the term 'vortex-tube' used in Fluid dynamics please see Vorticity The vortex tube, also known as the Ranque-Hilsch vortex It sorts molecules by exploiting the conservation of angular momentum: hotter molecules are spun to the outside of the tube while cooler molecules spin in a tighter whirl within the tube. Gas from the two different temperature whirls may be vented on opposite ends of the tube. Although this creates a temperature difference, the energy to do so is supplied by the pressure driving the gas through the tube.

If hypothetical mirror matter exists, demons can be envisaged which can act like perpetuum mobiles of the second kind: extract heat energy from only one reservoir, use it to do work and be isolated from the rest of ordinary world. In Physics, mirror matter, also called shadow matter or Alice matter, is a hypothetical counterpart to ordinary matter Yet the Second Law is not violated because the demons pay their entropy cost in the hidden (mirror) sector of the world by emitting mirror photons.

Experimental work based on Maxwell's Demon

In the 1 February 2007 issue of Nature, David Leigh, a professor at the University of Edinburgh, announced the creation of a nano-device based on this thought experiment. Events 1327 - Teenaged Edward III is crowned King of England, but the country is ruled by his mother Queen Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Nature is a prominent Scientific journal, first published on 4 November 1869 The University of Edinburgh (Oilthigh Dhùn Èideann founded in 1582 is a renowned centre for teaching and research in Edinburgh, Scotland, UK. This device is able to drive a chemical system out of equilibrium, but it must be powered by an external source (light in this case) and therefore does not violate thermodynamics. In a Chemical process, chemical equilibrium is the state in which the chemical activities or Concentrations of the reactants and products have no net change Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700

Previously, other researchers created a ring-shaped molecule which could be placed on an axle connecting two sites (called A and B). Particles from either site would bump into the ring and move it from end to end. If a large collection of these devices were placed in a system, half of the devices had the ring at site A and half at B at any given moment in time.

Leigh made a minor change to the axle so that if a light is shone on the device, the center of the axle will thicken, thus restricting the motion of the ring. It only keeps the ring from moving, however, if it is at site A. Over time, therefore, the rings will be bumped from site B to site A and get stuck there, creating an imbalance in the system. In his experiments, Leigh was able to take a pot of "billions of these devices" from 50:50 equilibrium to a 70:30 imbalance within a few minutes. [3]

Adams and the demon as historical metaphor

Historian Henry Brooks Adams in his manuscript The Rule of Phase Applied to History attempted to use Maxwell's demon as a historical metaphor, though he misunderstood and misapplied the original principle. Henry Brooks Adams ( February 16 1838 &ndash March 27 1918) was an American Novelist, Journalist, Historian Metaphor (from the Greek: μεταφορά - metaphora, meaning "transfer" is language that directly compares seemingly unrelated subjects [4] Adams interpreted history as a process moving towards "equilibrium", but he saw militaristic nations (he felt Germany pre-eminent in this class) as tending to reverse this process, a Maxwell's Demon of history. History is the study of the past particularly the written record Those who study history as a Profession are called Historians Etymology Militarism is the belief or desire of a government or people that a country should maintain a strong military capability and be prepared to use it aggressively to defend or Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. Adams made many attempts to respond to the criticism of his formulation from his scientific colleagues, but the work remained incomplete at Adams' death in 1918. Year 1918 ( MCMXVIII) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common It was only published posthumously. [5]

Maxwell's demon in popular culture

In literature, Maxwell’s Demon appears in Thomas Pynchon's novels, The Crying of Lot 49 and Gravity's Rainbow. Thomas Ruggles Pynchon Jr (born May 8 1937 is an American writer based in New York City, noted for his dense and complex works of Fiction. The Crying of Lot 49 ( 1966) is a Novel by the Author Thomas Pynchon. Gravity's Rainbow is an epic postmodern novel written by Thomas Pynchon and first published on February 28 1973. and in George Gamow's Mr. Tompkins. George Gamow (pronounced as ˈgamof ( March 4, 1904 &ndash August 19, 1968), born Georgiy Antonovich Gamov (Георгий Антонович The eponymous character of Mr Tompkins appears in a series of books by the physicist George Gamow in which he aims to explain Also, it is mentioned in the Novel Homo Faber by Swiss author Max Frisch, as well as in one of the short stories of The Cyberiad by Stanisław Lem: "The Sixth Sally, or How Trurl and Klaupacius Created a Demon of the Second Kind to Defeat the Pirate Pugg". Homo Faber A Report is a Novel by Max Frisch, first published in 1957 Switzerland (English pronunciation; Schweiz Swiss German: Schwyz or Schwiiz Suisse Svizzera Svizra officially the Swiss Confederation Max Frisch ( May 15, 1911 &ndash April 4, 1991) was a Swiss Architect, Playwright and Novelist, regarded The Cyberiad (Cyberiada is a series of short stories by Stanisław Lem. Stanisław Lem ( sta'ɲiswaf lɛm 12 September 1921 – 27 March 2006 was a Polish Science fiction, philosophical and satirical writer In Greg Egan's hard science fiction novel Permutation City, Maxwell's Demon is the name of a program used by the character Maria to keep track of individual "molecules" in the cellular automaton known as the Autoverse. Finally, Maxwell's Demon appears, and fills his typical role, in the climax of the book Master of the Five Magics by Lyndon Hardy. Master of the Five Magics is a Fantasy novel by Lyndon Hardy, first published in 1980 Lyndon Maurice Hardy (born 1941 Author physicist/fantasist Member of the Science Fiction Writers of America. Maxwell's Demon was also mentioned in Christopher Stasheff's books from the series A Wizard in Rhyme, wherein he let Maxwell's Demon (Max for short) help out the main character.

In the way of short stories, an homage to Maxwell has been written by Isaac Asimov and Larry Niven. Isaac Asimov (c January 2 1920 &ndash April 6 1992 ˈaɪzək ˈæzɪmʌv originally Исаак Озимов but now transcribed into Russian as, was a Russian Laurence van Cott Niven (born April 30, 1938 Los Angeles California) is a US Science fiction author. Additionally, Larry Niven's Warlock in The Magic Goes Away uses such a demon to cool his home in a vignette titled "Unfinished Story" as published in "Playgrounds of the Mind". Laurence van Cott Niven (born April 30, 1938 Los Angeles California) is a US Science fiction author. The Magic Goes Away is a Fantasy Short story written by Larry Niven in 1976 and later expanded to a Novella of the same name which The Demon also contributes to the thesis of Ken Kesey's collection of stories, The Demon Box. Kenneth Elton Kesey ( September 17, 1935 &ndash November 10, 2001) was an American Author, best known for his major novels In the story "A Feast of Demons" by William Morrison (pseudonym for Joseph Samachson), a scientist creates Maxwell's Demons to change the temperature of items, the purity of ores, and eventually even reverse or accelerate the aging process in people--only to have the Demons escape and wreak havoc on civilization. Dr Joseph "Joe" Samachson (1906&ndash1980 was a Scientist and Author, primarily of Science fiction and comic books


In music and film, Maxwell Demon was the name of Brian Eno's first band, which was the inspiration for the name of a fictional character in the movie Velvet Goldmine, and Maxwell's Demon is the name of a 1968 film by the American experimental filmmaker Hollis Frampton. Brian Peter George St John le Baptiste de la Salle Eno (born 15 May 1948 commonly known as Brian Eno (ˈiːnoʊ is an English Musician, producer Velvet Goldmine is a 1998 film directed and co-written by Todd Haynes. Hollis Frampton (1936-1984 was an American Avant-garde filmmaker photographer writer/theoretician and a pioneer of digital art Maxwell's Demon is mentioned in the song 'A Metaphysical Drama', by Vintersorg and also is the name of a Brooklyn-based indie rock band, as well as that of a London alt-pop band.

See also

Notes

  1. ^ Maxwell (1871), reprinted in Leff & Rex (1990) at p. In the History of science, Laplace's demon is a hypothetical "demon" envisioned in 1814 by Pierre-Simon Laplace such that if it knew the precise location Evaporation is the process by which Molecules in a Liquid state (e Thermionic emission is the flow of Charge carriers from a surface or over some other kind of Electrical potential barrier caused by thermal vibrational energy Introduction When a Metallic surface is exposed to Electromagnetic radiation above a certain threshold Frequency, the light is absorbed and Electrons In Physics, the Joule–Thomson effect or Joule–Kelvin effect describes the Temperature change of a gas or liquid when it is forced through a Valve The Hall effect refers to the Potential difference ( Hall voltage) on the opposite sides of an Electrical conductor through which there is an Electric Mass spectrometry is an analytical technique that identifies the chemical composition of a compound or sample based on the Mass-to-charge ratio of charged particles Catalysis is the process in which the rate of a Chemical reaction is increased by means of a Chemical substance known as a catalyst In Quantum mechanics, quantum tunnelling is a nanoscopic phenomenon in which a particle violates the principles of Classical mechanics by penetrating a Originally considered by Josiah Willard Gibbs in his paper On the Equilibrium of Heterogeneous Substances, the Gibbs Paradox (Gibbs' paradox or 4
  2. ^ http://www.ulearntoday.com/magazine/physics_article1.jsp?FILE=maxwelldemon
  3. ^ Sanderson, Kathrine (2007-01-31). Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1504 - France cedes Naples to Aragon. 1606 - Gunpowder Plot: Guy Fawkes A demon of a device. Nature. com. Retrieved on 2007-02-01. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1327 - Teenaged Edward III is crowned King of England, but the country is ruled by his mother Queen
  4. ^ Cater (1947), pp640-647, see also the paper by Daub (1970) reprinted in Leff & Rex (1990), pp37-51.
  5. ^ Adams (1919), p. 267
  1. Physical entropy and information entropy

External links and bibliography

Dictionary

Maxwell's demon

-noun

  1. A hypothetical creature created for a thought experiment. Maxwell’s demon, if it existed, would act as a sort of gate guard by sorting between higher-energy molecules and lower-energy molecules within an enclosed space. Because such a sorting process would tend to decrease entropy, it would violate the second law of thermodynamics.
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