Maxwell's demon is an 1867 thought experiment by the Scottish physicist James Clerk Maxwell, meant to raise questions about the possibility of violating the second law of thermodynamics. Year 1867 (MDCCCLXVII) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Sunday of the 12-day slower Julian calendar). ... In philosophy, physics, and other fields, a thought experiment (from the German Gedankenexperiment) is an attempt to solve a problem using the power of human imagination. ... This article is about the country. ... Not to be confused with physician, a person who practices medicine. ... James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and theoretical physicist from Edinburgh, Scotland, UK. His most significant achievement was aggregating a set of equations in electricity, magnetism and inductance — eponymously named Maxwells equations — including an important modification (extension) of the Ampères... The second law of thermodynamics is an expression of the universal law of increasing entropy. ...

Maxwell's thought experiment

The Second Law of Thermodynamics forbids (due to statistical improbability) two bodies of equal temperature, brought in contact with each other and isolated from the rest of the Universe, from evolving to a state in which one of the two has a significantly higher temperature than the other. The second law is also expressed as the assertion that in an isolated system, entropy never decreases. Maxwell described his thought experiment in this way^[1]: The second law of thermodynamics is an expression of the universal law of increasing entropy. ... For other uses, see Temperature (disambiguation). ... In thermodynamics, an isolated system, as contrasted with a closed system, is a physical system that does not interact with its surroundings. ... For a less technical and generally accessible introduction to the topic, see Introduction to entropy. ...

... 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

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. Observing the molecules on both sides, a little "demon" guards a trapdoor between the two containers. 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. However, since average molecular speed corresponds to temperature, the temperature will have decreased in A and increased in B; this is contrary to the second law of thermodynamics. Image File history File links Maxwell's_demon. ... Image File history File links Maxwell's_demon. ... For other uses, see Gas (disambiguation). ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... This article does not cite any references or sources. ...

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 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. The second law of thermodynamics is an expression of the universal law of increasing entropy. ...

One of the most famous responses to this question was suggested in 1929 by Leó Szilárd and later by Léon Brillouin. 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. 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. Year 1929 (MCMXXIX) was a common year starting on Tuesday (link will display the full calendar) of the Gregorian calendar. ... Leó Szilárd (February 11, 1898 – May 30, 1964 Originally Szilárd Leó) was a Jewish Hungarian-American physicist who conceived the nuclear chain reaction and worked on the Manhattan Project. ... Léon N. Brillouin (August 7, 1889-1969) was a French physicist. ... The second law of thermodynamics is an expression of the universal law of increasing entropy. ...

Szilárd's insight was expanded upon in 1982 by Charles H. Bennett. In 1960, Rolf Landauer realized that certain measurements need not increase thermodynamic entropy as long as they were thermodynamically reversible. 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. Erasing information is a thermodynamically irreversible process that increases the entropy of a system.^[2] Year 1982 (MCMLXXXII) was a common year starting on Friday (link displays the 1982 Gregorian calendar). ... Charles H. Bennett Charles H. Bennett is an IBM Fellow at IBM Research. ... Rolf Landauer (1927 – 1999) was an IBM physicist who in 1961 demonstrated that when information is lost in an irreversible circuit, the information becomes entropy and an associated amount of energy is dissipated as heat. ... In thermodynamics, a reversible process (or reversible cycle if the process is cyclic) is a process that can be reversed by means of infinitesimal changes in some property of the system. ... Charles H. Bennett Charles H. Bennett is an IBM Fellow at IBM Research. ...

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. These explanations, however, are inadequate as the concept of the demon is not stated and may work as described below. Work (abbreviated W) is the energy transferred in applying force over a distance. ...

Furthermore, John Earman and John Norton have argued that Szilard and Landauer's explanations for why 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 is a philosopher of physics. ... The second law of thermodynamics is an expression of the universal law of increasing entropy. ...

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 refers broadly to a field of applied science and technology whose unifying theme is the control of matter on the atomic and molecular scale, normally 1 to 100 nanometres, and the fabrication of devices within that size range. ...

A large-scale, commercially-available pneumatic device, called a Ranque-Hilsch vortex tube separates hot and cold air. 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. The vortex tube, also known as the Ranque-Hilsch vortex tube, is a mechanical device that separates gas into hot and cold streams. ...

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. 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. In physics, mirror matter, also called shadow matter or Alice matter, is a hypothetical counterpart to regular matter suggested by Tsung Dao Lee and Chen Ning Yang [1] in 1956, when it was discovered that nature violates P-symmetry. ...

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. 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. is the 32nd day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... Nature is a prominent scientific journal, first published on 4 November 1869. ... David Leigh(scientist) redirects here. ... The University of Edinburgh (Scottish Gaelic: ), founded in 1582,[4] is a renowned centre for teaching and research in Edinburgh, Scotland. ... Apparatus for carrying out acid-base titration. ... This article does not cite any references or sources. ...

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.^[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. 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. It was only published posthumously. ^[5] Henry Brooks Adams (February 16, 1838 - March 27, 1918) was a U.S. historian, journalist and novelist. ... This article is about metaphor in literature and rhetoric. ... This article is about the study of time in human terms. ... Militarism or militarist ideology is the doctrinal view of a society as being best served (or more efficient) when it is governed or guided by concepts embodied in the culture, doctrine, system, or people of the military. ... 1918 (MCMXVIII) was a common year starting on Tuesday of the Gregorian calendar (see link for calendar) or a common year starting on Wednesday of the Julian calendar. ...

Maxwell's demon in popular culture

In literature, Maxwell’s Demon appears in Thomas Pynchon's novel, The Crying of Lot 49 and George Gamow's Mr. Tompkins. 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". 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. 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. Thomas Ruggles Pynchon, Jr. ... The Crying of Lot 49 (1966) is a novel by the author Thomas Pynchon. ... George Gamow (pronounced GAM-off) (March 4, 1904 – August 19, 1968) , born Georgiy Antonovich Gamov (Георгий Антонович Гамов) was a Ukrainian born physicist and cosmologist. ... The eponymous character of Mr. ... Homo faber (Latin for Man the Smith or Man the Maker; in reference to the biological name for man, Homo sapiens meaning man the wise) is a concept articulated by Hannah Arendt and Max Frisch. ... Max Frisch (May 15, 1911 – April 4, 1991), was a Swiss architect, playwright and novelist, one of the most representative writers of German literature after World War II. In his creative works Frisch paid particular attention to issues relating to problems of personal identity, morality and political commitment. ... The Cyberiad is a series of short stories by StanisÅ‚aw Lem. ... StanisÅ‚aw Lem ( , September 12, 1921 – March 27, 2006) was a Polish science fiction, philosophical and satirical writer. ... Master of the Five Magics is a fantasy novel by Lyndon Hardy, first published in 1980. ... Lyndon Maurice Hardy (born 1941) Author; physicist/fantasist. ...

In the way of short stories, A homage to Maxwell has been written by Isaac Asimov and Larry Niven. 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". The Demon also contributes to the thesis of Ken Kesey's collection of stories, The Demon Box. Isaac Asimov (January 2?, 1920?[1] – April 6, 1992), IPA: , originally Исаак Озимов but now transcribed into Russian as Айзек Азимов) was a Russian-born American Jewish author and professor of biochemistry, a highly successful and exceptionally prolific writer best known for his works of science fiction and for his popular science books. ... This article does not cite any references or sources. ... This article does not cite any references or sources. ... The Warlocks Era (The Magic Goes Away) The fictional setting of Larry Nivens logical (as opposed to high) fantasy series. ... Kenneth Elton Kesey (September 17, 1935 – November 10, 2001) was an American author, best known for his novel, One Flew Over the Cuckoos Nest, and as a counter-cultural figure who, some consider, was a link between the beat generation of the 1950s and the hippies of the 1960s. ...

References to Maxwell’s Demon has also been referenced to in manga and video games, as well as cartoons. Oh My Goddess! by Kosuke Fujishima depicts the Demon as a spirit capable of generating what amounts to a miniature ramjet. Maxwell's Demon is a villain in the fictional cartoon show 'Captain Baseball Bat Boy', featured in the video game Max Payne 2: The Fall of Max Payne. During the game, a character is quizzed on his knowledge of the show to save his life. The question being "Who was the original creator of Maxwell's Demon?", the character cited both the Captain Baseball bat-boy character who created the demon, as well as the show's writer, but was killed for not answering "James Clerk Maxwell". In August 08, 2005 strip of the webcomic Mac Hall, a hallucinated Maxwell's Demon is found in the air conditioner. Some Windows releases came with a very simple game called "Maxwell's Maniac", in which you play the part of Maxwell's Demon by moving a sliding door to try to coax red molecules to one side of a chamber and blue molecules to the other. This article is about the comics published in East Asian countries. ... Serialized in Afternoon (magazine) Super Manga Blast Original run 1988-08-25 – ongoing No. ... Kosuke Fujishima (藤島 康介 Fujishima Kōsuke) (born July 7, 1964) is a Japanese manga artist. ... A ramjet, sometimes referred to as a stovepipe jet, is a type of jet engine. ... Max Payne 2: The Fall of Max Payne is a third-person shooter developed by Remedy Entertainment for the PC, Xbox, and PlayStation 2 systems. ... Mac Hall (debut: 2000-11-07) is a webcomic which was created through a bet between the creator Ian McConville and a friend who claimed he couldnt make a comic like Penny Arcade.[1] After the fifteenth comic, McConville was joined by Matt Boyd who began to write the... Screenshot of Maxwells Maniac, showing red, blue, and gray molecules and bricks Maxwells Maniac is a computer game originally part of the Microsoft Entertainment Pack series. ...

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. Maxwell's Demon is mentioned in the song 'A Metaphysical Drama', by Vintersorg and also is also the name of a London alt-pop band. Brian Eno (pronounced ) born on 15 May 1948 in Woodbridge, Suffolk, England) is an English electronic musician, music theorist and record 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, and a pioneer of digital art. ...

See also

• Laplace's demon
• Evaporation
• Thermionic emission
• Photoelectric effect
• Joule-Thomson effect
• Hall effect
• Mass spectrometry
• Dispersion
• Catalysis
• Quantum tunnelling
• Gibbs paradox

In the history of science, Laplaces demon is a hypothetical demon envisioned in 1814 by Pierre-Simon Laplace such that if it knew the precise location and momentum of every atom in the universe then it could use Newtons laws to reveal the entire course of cosmic events... “Vaporization” redirects here. ... Closeup of the filament on a low pressure mercury gas discharge lamp showing white thermionic emission mix coating on the central portion of the coil. ... A diagram illustrating the emission of electrons from a metal plate, requiring energy gained from an incoming photon to be more than the work function of the material. ... In physics, the Joule-Thomson effect, or Joule-Kelvin effect, is a process in which the temperature of a real gas is either decreased or increased by letting the gas expand freely at constant enthalpy (which means that no heat is transferred to or from the gas, and no external... Hall effect diagram, showing electron flow (rather than conventional current). ... Mass spectrometry (previously called mass spectroscopy (deprecated)[1] or informally, mass-spec and MS) is an analytical technique used to measure the mass-to-charge ratio of ions. ... Dispersion can mean any of several things: A phenomenon that causes the separation of a wave into components of varying frequency. ... In chemistry and biology, catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance, called a catalyst, that is itself not consumed by the overall reaction. ... In quantum mechanics, quantum tunnelling is a micro and nanoscopic phenomenon in which a particle violates principles of classical mechanics by penetrating or passing through a potential barrier or impedance higher than the kinetic energy of the particle. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

Notes

1. ^ Maxwell (1871), reprinted in Leff & Rex (1990) at p.4
2. ^ http://www.ulearntoday.com/magazine/physics_article1.jsp?FILE=maxwelldemon
3. ^ Sanderson, Kathrine (2007-01-31). A demon of a device. Nature.com. Retrieved on 2007-02-01.
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

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 32nd day of the year in the Gregorian calendar. ...

External links and bibliography

• University of Edinburgh's recent findings on soon-to-be-possible Maxwell's Demon
• Sciencenews.org article about Maxwell's Demon
• Adams, H. (1919). The Degradation of the Democractic Dogma. New York: Kessinger. ISBN 1-4179-1598-6. 
• Bennet, C.H. (1987) "Demons, Engines and the Second Law", Scientific American, November, pp108-116
• Cater, H.D (ed.) (1947). Henry Adams and his Friends. Boston. 
• Daub, E.E. (1967). "Atomism and Thermodynamics". Isis 58: 293-303. 
• Earman, J. and Norton, J. (1998). "Exorcist XIV: The Wrath of Maxwell's Demon. Part I. From Maxwell to Szilard". Studies In History and Philosophy of Science Part B: Studies In History and Philosophy of Modern Physics 29: 435-471. 
• Earman, J. and Norton, J. (1999). "Exorcist XIV: The Wrath of Maxwell's Demon. Part II. From Szilard to Landauer and Beyond". Studies In History and Philosophy of Science Part B: Studies In History and Philosophy of Modern Physics 30: 1-40. 
• Feynmann, R.P. et al. (1996). Feynman Lectures on Computation. Addison-Wesley. ISBN 0-14-028451-6. , pp148-150
• Jordy, W.H. (1952). Henry Adams: Scientific Historian. New Haven. ISBN 0-685-26683-4. 
• Leff, H.S. & Rex, A.F. (eds) (1990). Maxwell's Demon: Entropy, Information, Computing. Bristol: Adam-Hilger. ISBN 0-7503-0057-4. , may be out of print but contains several papers not in 2003 edition.
• - (2003). Maxwell's Demon 2: Entropy, Classical and Quantum Information, Computing. Institute of Physics. ISBN 0-7503-0759-5. , Contents - an anthology and comprehensive bibliography of academic papers pertaining to Maxwell's demon and related topics. Chapter 1 provides a historical overview of the demon's origin and solutions to the paradox.
• Maxwell, J.C. (1871). Theory of Heat. , reprinted (2001) New York: Dover, ISBN 0-486-41735-2
• Norton, J. (2005). "Eaters of the lotus: Landauer's principle and the return of Maxwell's demon". Studies In History and Philosophy of Science Part B: Studies In History and Philosophy of Modern Physics 36: 375-411.