Perpetual motion
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2008-07-16T22:12:24Z
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[[Image:WaterScrewPerpetualMotion.png|thumb|right|The "water screw" perpetual motion machine from a 1660 woodcut.]]
The term '''perpetual motion''', taken literally, refers to movement that goes on forever. However, the term more generally refers to any closed system that produces more energy than it consumes. Such a device or system would be in violation of the law of [[conservation of energy]], which states that energy can never be created or destroyed, and is therefore impossible. The most conventional type of perpetual motion machine is a mechanical system which (supposedly) sustains motion while inevitably losing energy to [[friction]] and [[air resistance]].
== Basic principles ==
{{main|Thermodynamics}}
Perpetual motion violates either the [[first law of thermodynamics]], the [[second law of thermodynamics]], or both. The first law of thermodynamics is essentially a statement of conservation of energy. The second law has several statements, the most intuitive of which is that [[heat]] flows spontaneously from hotter to colder places; the most well known statement is that [[entropy]] tends to increase, or at the least stay the same; another statement is that no heat engine (an engine which produces work while moving heat between two places) can be more efficient than a [[Carnot heat engine]]. As a special case of this, any machine operating in a closed cycle cannot ''only'' transform thermal energy to work in a region of constant temperature.
Machines which are claimed not to violate either of the two laws of thermodynamics but rather are claimed to generate energy from unconventional sources are sometimes referred to as perpetual motion machines, although they are generally reported as not meeting the standard criteria for the name. By way of example, it is quite possible to design a clock or other low-power machine to run on the differences in barometric pressure or temperature between night and day.<ref>[[Cox's timepiece]]</ref> Such a machine has a source of energy, albeit one from which it is quite impractical to produce power in quantity.
=== Classification ===
It is customary to classify perpetual motion machines according to which law of thermodynamics it attempts to violate:
:1. A '''perpetual motion machine of the first kind''' produces [[energy]] from nothing, giving the user unlimited 'free' energy. It thus violates the [[law of conservation of energy]].
:2. A '''perpetual motion machine of the second kind''' is a machine which spontaneously converts thermal energy into mechanical work. This need not violate the law of conservation of energy, since the thermal energy may be equivalent to the work done; however it does violate the more subtle [[second law of thermodynamics]] (see also [[entropy]]). Note that such a machine is different from real heat engines (such as car engines), which always involve a transfer of heat from a hotter reservoir to a colder one, the latter being warmed up in the process. The signature of a perpetual motion machine of the second kind is that there is only one single heat reservoir involved, which is being spontaneously cooled without involving a transfer of heat to a cooler reservoir. This conversion of heat into useful work, without any side effect, is impossible by the second law of thermodynamics.
:What may prove more useful is to explain the existence of hot reservoirs to begin with. A hot reservoir inside an internal combustion engine is created by a spark igniting fumes which contain stores of chemical energy. The temperature of the fumes increases above that of the surroundings. This is '''not''' a perpetual motion machine since the ability to raise the temperature above that of the surroundings depends on finite chemical reactions always less than the total heat energy and mass-energy contained within the system. Since there are far more states in which heat distribution is closer to thermodynamic equilibrium than states in which heat is concentrated in small regions, heat will tend to smooth out over time to lower power densities of increasingly unusable forms.
:3. A '''perpetual motion machine of the third kind''' would try to violate the [[third law of thermodynamics]], which says that nothing can be cooled to [[absolute zero]] and that [[entropy]] approaches zero as the temperature of a system approaches absolute zero. There are no known attempts to build a machine of this type {{harvcol|Schadewald|2008|pp=55-56}}.
In an otherwise completely empty Newtonian universe, a single particle could travel forever at a constant velocity with no violation of the laws of physics – though of course no energy could be extracted from it without slowing it down. For example, in an isolated system consisting of two objects orbiting each other gravitationally, the two objects will remain orbiting forever, as long as they are not disturbed. However any attempt to extract useful work from this system would lead to a loss of energy. This would result in the objects slowing down and getting closer to each other, until at some point the objects would collapse together and no more energy would remain to extract.
=== Use of the term "impossible" and perpetual motion ===
Scientists and engineers accept the possibility that the current understanding of the laws of physics may be incomplete or incorrect; a perpetual motion device may not be ''impossible'', but overwhelming evidence would be required to justify rewriting the laws of physics: [[extraordinary claims require extraordinary evidence]].
The conservation laws are particularly robust. [[Noether's theorem]] states that any conservation law can be derived from a corresponding continuous symmetry.<ref name='Goldstein'>{{cite book | last = Goldstein | first = Herbert | authorlink = | coauthors = Charles Poole and John Safko | title = Classical Mechanics 3rd edition | publisher = Addison Wesley | date = 2002 | location = San Francisco, CA | pages = 589-598 | url = | doi = | id = | isbn = 0-201-65702-3 }}</ref> In other words, as long as the laws of physics (not simply the current understanding of them, but the actual laws, which may still be undiscovered) and the various physical constants remain invariant over time — as long as the laws of the universe are fixed — then the conservation laws ''must'' be true, in the sense that they follow from the presupposition using [[mathematical logic]]. To put it the other way around: if perpetual motion or "'''overunity'''" machines were possible, then most of what we believe to be true about physics, mathematics, or both would have to be false. This problem is exacerbated by the fact that mathematics is believed to be absolute, since its veracity is not dependent on anything that happens in the real world.
Of course the universe does not have to conform to our belief of how it works. In this case it is easy to check whether or not the theory is correct. Using telescopes we can examine the universe in the distant past; the fact that stars even exist and are, to the limits of our measurements, identical to stars today, is a direct visual demonstration that physics was similar in the past. Combining different measurements such as [[spectroscopy]], direct measurement of the [[SN1987A|speed of light in the past]] and similar measurements demonstrates conclusively that physics has remained substantially the same, if not identical, for all of observable history spanning billions of years.
The principles of thermodynamics are so well established, both theoretically and experimentally, that proposals for perpetual motion machines are universally met with disbelief on the part of physicists. Any proposed perpetual motion design offers a potentially instructive challenge to physicists: one is almost completely certain that it can't work, so one must explain ''how'' it fails to work. The difficulty (and the value) of such an exercise depends on the subtlety of the proposal; the best ones tend to arise from physicists' own [[thought experiment]]s and often shed light into unique aspects of physics.
<blockquote>The law that [[entropy]] always increases, holds, I think, the supreme position among the [[laws of Nature]]. If someone points out to you that your pet theory of the [[universe]] is in disagreement with [[Maxwell's equations]] — then so much the worse for Maxwell's equations. If it is found to be contradicted by observation — well, these experimentalists do bungle things sometimes. But if your theory is found to be against the ''second law of thermodynamics'' I can give you no hope; there is nothing for it but to collapse in deepest humiliation. — Sir [[Arthur Stanley Eddington]], ''The Nature of the Physical World'' (1927)</blockquote>
=== Thought experiments ===
Serious work in [[theoretical physics]] often involves thought experiments that test the boundaries of understanding of physical laws. Some such thought experiments involve apparent perpetual motion machines, and insight may be had from understanding ''why'' they either don't work or don't violate the laws of physics.
* [[Maxwell's demon]]: A thought experiment which led to physicists' considering the interaction between entropy and [[Physical information|information]].
* [[Richard Feynman|Feynman]]'s "[[Brownian ratchet]]": A "perpetual motion" machine which extracts work from thermal fluctuations and appears to run forever but really only runs as long as the environment is warmer than the ratchet.
* Self-perpetuating [[cosmic inflation]]: [[Andrei Linde]] has proposed that during the theoretical period of cosmic inflation in the early universe, quantum fluctuations in energy could be magnified by the very inflationary process, preventing the global cooling trend from ever being fully consummated. This would violate both the first and second laws of thermodynamics; indeed, it may constitute the origin of a low-entropy past that gets the second law going in the first place. However, a machine to harness this principle would have several serious flaws. It would need to use unimaginable amounts of energy (on at least a [[Planck units|Planck scale]]); it might have cataclysmic consequences to the area around it for an unknown distance (there is not a prior natural limit to the scale of the damage); and at least the majority and possibly all the energy it generated would be in a newly-created universe which might be inaccessibly far away along a [[wormhole]].
=== Techniques ===
{{Rquote|right|One day man will connect his apparatus to the very wheelwork of the universe [...] and the very forces that motivate the planets in their orbits and cause them to rotate will rotate his own machinery.|[[Nikola Tesla]]|}}
Some common ideas recur repeatedly in perpetual motion machine designs.
The seemingly mysterious ability of [[magnet]]s to influence motion at a distance without any apparent energy source has long appealed to inventors. However, a constant magnetic field can do no [[work (physics)|work]] because the force it exerts on a charged particle is always at right angles to its motion; a changing field can do work, but requires energy to sustain. A "fixed" magnet can do work, but energy is dissipated in the process, typically weakening the magnet's strength over time. Thus, when a magnet does work by lifting an iron weight, potential energy is converted to kinetic energy. Once the iron hits the magnet its kinetic energy is converted to heat and sound. In order to release further energy, the iron must be moved away from the magnet. This converts the energy of your arm to potential energy again. Since the energy of parting the magnet and iron is identical to the energy released as the magnet and iron come together, no net energy can be gained by changing the iron – magnet distance.
[[Image:Perpetuum mobile villard de honnecourt.jpg|thumb|Perpetuum Mobile of [[Villard de Honnecourt]] (about 1230).]]
[[Gravity]] also acts at a distance, without an apparent energy source. But to get energy out of a gravitational field (for instance, by dropping a heavy object, producing kinetic energy as it falls) you have to put energy in (for instance, by lifting the object up), and some energy is always dissipated in the process. A typical application of gravity in a perpetual motion machine is [[Bhaskara II|Bhaskara]]'s wheel in the 12th century, whose key idea is itself a recurring theme, often called the [[overbalanced wheel]]: Moving weights are attached to a wheel in such a way that they fall to a position further from the wheel's center for one half of the wheel's rotation, and closer to the center for the other half. Since weights further from the center apply a greater [[torque]], the result is (or would be, if such a device worked) that the wheel rotates forever. The moving weights may be hammers on pivoted arms, or rolling balls, or mercury in tubes; the principle is the same.
Gravity and magnetism are an attractive combination indeed, and a frequently rediscovered design has a ball pulled up by a magnetic field and then rolling down under the influence of gravity, in a cycle. (At the highest point, the ball is supposed to have acquired enough speed to escape the magnet's influence.)
Yet another theoretical machine involves a frictionless environment for motion. This involves the use of diamagnetic or electromagnet levitation to float an object. This is done in a vacuum to eliminate air friction and friction from an axle. The levitated object is then free to rotate around its center of gravity without interference. However, this machine has no practical purpose because the rotated object cannot do any work as work requires the levitated object to cause motion in other objects, bringing friction into the problem.
To extract work from heat, thus producing a perpetual motion machine of the second kind, the most common approach (dating back at least to [[Maxwell's demon]]) is ''unidirectionality''. Only molecules moving fast enough and in the right direction are allowed through the demon's trap door. In a [[Brownian ratchet]], forces tending to turn the ratchet one way are able to do so while forces in the other direction aren't. A diode in a heat bath allows through currents in one direction and not the other. These schemes typically fail in two ways: either maintaining the unidirectionality costs energy (Maxwell's demon needs light to look at all those particles and see what they're doing), or the unidirectionality is an illusion and occasional big violations make up for the frequent small non-violations (the Brownian ratchet will be subject to internal Brownian forces and therefore will sometimes turn the wrong way).
== Invention history==
{{main|History of perpetual motion machines}}
[[Image:OrffyreusWheel.png|thumb|333px|Orffyreus Wheel. The device was designed by [[Johann Bessler]].]]
The recorded history of referenced perpetual motion machines date back to the 12th century. Proponents of perpetual motion machines use a number of other terms to describe their inventions, including "[[Second law of thermodynamics|free energy]]" and "over unity" machines. The earliest references to perpetual motion machines date back to 1150, by an [[India]]n [[Indian mathematics|mathematician]]-[[astronomer]], [[Bhāskara II]]. He described a wheel that he claimed would run forever.<ref>[[Lynn Townsend White, Jr.]] (April 1960). "Tibet, India, and Malaya as Sources of Western Medieval Technology", ''The American Historical Review'' '''65''' (3), p. 522-526.</ref> [[Villard de Honnecourt]] in 1235 described, in a thirty-three page manuscript, a perpetual motion machine of the second kind. [[Robert Boyle]]'s self-flowing flask appears to fill itself through [[siphon]] action. This is not possible in reality; a siphon requires its "output" to be lower than the "input".
In 1775 Royal Academy of Sciences in Paris issued the statement that Academy "will no longer accept or deal with proposals concerning perpetual motion". [[Johann Bessler]] (also known as Orffyreus) created a series of claimed perpetual motion machines in the 18th Century. In the 19th century, the invention of perpetual motion machines became an obsession for many scientists. Many machines were designed based on electricity, but none of them lived up to their promises. Another early prospector in this field was [[John Gamgee]]. Gamgee developed the [[Zeromotor]], a perpetual motion machine of the second kind.
Devising these machines is a favourite pastime of many [[eccentricity (behaviour)|eccentric]]s, who often come up with elaborate machines in the style of [[Rube Goldberg]] or [[Heath Robinson]]. These designs may appear to work on paper at first glance. Usually, though, various flaws or obfuscated external power sources have been incorporated into the machine. Such activity has made them useless in the practice of "[[invention]]".
===Patents===
Devising such inoperable machines has become common enough that the [[United States Patent and Trademark Office]] (USPTO) has made an official policy of refusing to grant [[patent]]s for perpetual motion machines without a working model. The USPTO Manual of Patent Examining Practice states:
: ''With the exception of cases involving perpetual motion, a model is not ordinarily required by the Office to demonstrate the operability of a device. If operability of a device is questioned, the applicant must establish it to the satisfaction of the [[patent examiner|examiner]], but he or she may choose his or her own way of so doing''.<ref>[http://www.uspto.gov/web/offices/pac/mpep/documents/0600_608_03.htm 608.03 Models, Exhibits, Specimens [R-3] – 600 Parts, Form, and Content of Application]</ref>
And, further, that:
: ''A rejection ''[of a patent application]'' on the ground of lack of utility includes the more specific grounds of inoperativeness, involving perpetual motion. A rejection under 35 U.S.C. 101 for lack of utility should not be based on grounds that the invention is frivolous, fraudulent or against public policy.''<ref>[http://www.uspto.gov/web/offices/pac/mpep/documents/0700_706_03_a.htm#sect706.03a 706.03(a) Rejections Under 35 U.S.C. 101 [R-3] – 700 Examination of Applications II. UTILITY]</ref>
The USPTO has granted a few patents for motors that are claimed to run without net energy input. Some of these are:
{| align="right" border="1" cellpadding="4" cellspacing="0" style="margin: 1em 1em 1em 1em; background: #f9f9f9; border: 1px #aaa solid; border-collapse: collapse;"
! Howard R. Johnson, U.S. Patent 4,151,431
|-
|[[Image:USPatent4151431-1.png|166px]][[Image:USPatent4151431-2.png|166px]]
|}
* [[Howard R. Johnson (inventor)|Johnson, Howard R.]], {{US patent|4151431}} "''[[Permanent magnet motor (free energy)|Permanent magnet motor]]''", [[April 24]], [[1979]]
* Baker, Daniel, {{US patent|4074153}} "''Magnetic propulsion device''", [[February 14]], [[1978]]
* Hartman; Emil T., {{US patent|4215330}} "''Permanent magnet propulsion system''", [[December 20]], [[1977]] (this device is related to the [[Simple Magnetic Overunity Toy]] ([[SMOT]])),
* Flynn; Charles J., {{US patent|6246561}} "''Methods for controlling the path of magnetic flux from a permanent magnet and devices incorporating the same", [[July 31]], [[1998]]
* Patrick, et al., {{US patent|6362718}} "''[[Motionless Electrical Generator|Motionless electromagnetic generator]]''" , [[March 26]], [[2002]]
* Green, Willie A., {{US patent|6526925}} "''Piston Driven Rotary Engine''", [[March 4]], [[2003]] "''Fluid driven device utilizing a leveraged system with minimal displacement''"
* Goldenblum, Halm, {{US patent|6962052}} "''Energy generation mechanism, device and system''", [[November 8]], [[2005]] "''A chamber with a partition which lets gas molecules flow one way and not the other. The pressure which builds up on one side of the partition is used to drive a generator.''"
* [[Joe Flynn (physicist)|Flynn, Joe]], {{US patent|6246561}} "''Methods for controlling the path of magnetic flux from a permanent magnet and devices incorporating the same''", [[June 12]], [[2001]]
* Gates; Glenn A., {{US patent|6523646}} "''Spring driven apparatus''", [[February 23]], [[2003]] "''Energy is stored in the springs and power is generated by way of the various forces which cause the springs to wind and unwind.''"
* McQueen; Jesse, {{US patent|7095126}} "''Internal energy generating power source''", [[August 22]], [[2006]] "''An external power source such as a battery is used to initially supply power to start an alternator and generator. Once the system has started it is not necessary for the battery to supply power to the system. The battery can then be disconnected. The alternator and electric motor work in combination to generator electrical power.''" Examiners: Schuberg, Darren ; Mohandesi, Iraj A.
In 1979, [[Joseph Newman (inventor)|Joseph Newman]] filed a US Patent application for his "[[Joseph Newman (inventor)|energy machine]]" which unambiguously claimed over-unity operation, where ''power output'' exceeded ''power input''; the source of energy was claimed to be the atoms of the machine's copper conductor.<ref>[http://findarticles.com/p/articles/mi_m1200/is_v127/ai_3794102 "A Patent Pursuit: Joe Newman's 'Energy Machine', ''Science News'', June 1, 1985]</ref> The Patent Office rejected the application after the [[National Bureau of Standards]] measured the electrical input to be greater than the electrical output. Newman challenged the decision in court and lost.<ref>[http://findarticles.com/p/articles/mi_m1200/is_v130/ai_4305182 "NBS Report Short Circuits Energy Machine", ''Science News'', July 5, 1986]</ref>
Other patent offices around the world have similar practices, such as the [[United Kingdom Patent Office]]. Section 4.05 of the UKPO Manual of Patent Practice states:
: ''Processes or articles alleged to operate in a manner which is clearly contrary to well-established physical laws, such as perpetual motion machines, are regarded as not having industrial application.''<ref>http://www.patent.gov.uk/practice-sec-004.pdf</ref>
Examples of decisions by the UK Patent Office to refuse patent applications for perpetual motion machines include: <ref> See also, for more examples of refused patent applications at the United Kingdom Patent Office ([[UK-IPO]]), [http://ipkitten.blogspot.com/2008/06/uk-ipo-gets-tougher-on-perpetual-motion.html ''UK-IPO gets tougher on perpetual motion''], [[IPKat]], 12 June 2008. Consulted on June 12, 2008. </ref>
: Decision BL O/044/06, John Frederick Willmott's application no. 0502841<ref>[http://www.patent.gov.uk/patent/p-decisionmaking/p-challenge/p-challenge-decision-results/o04406.pdf Patents Ex parte decision (O/044/06)<!-- Bot generated title -->]</ref>
: Decision BL O/150/06, Ezra Shimshi's application no. 0417271<ref>http://www.patent.gov.uk/patent/p-decisionmaking/p-challenge/p-challenge-decision-results/o15006.pdf</ref>
The [[European Patent Classification]] (ECLA) has classes including patent applications on perpetual motion systems: ECLA classes "F03B17/04: ''Alleged perpetua mobilia ...''" and "F03B17/00B: ''[... machines or engines] (with closed loop circulation or similar : ...Installations wherein the liquid circulates in a closed loop; Alleged perpetua mobilia of this or similar kind ...''". <ref> ECLA classes [http://v3.espacenet.com/eclasrch?ECLA=/espacenet/ecla/f03b/f03b17.htm?q=17-04 F03B17/04] and [http://v3.espacenet.com/eclasrch?ECLA=/espacenet/ecla/f03b/f03b17.htm?q=17-00b F03B17/00B]. Consulted on June 12, 2008. </ref>
==Apparent perpetual motion machines==
Even though they fully respect the laws of thermodynamics, there are a few conceptual or real devices that appear to be in "perpetual motion", while a closer analysis reveals them to actually "consume" some sort of natural resource or latent energy like the phase changes of [[water]] or other fluids, [[solar power|solar energy]] and natural, small temperature gradients. In general, extracting useful work out of similar devices is very hard or almost impossible, as those devices usually work with low-grade [[heat]] and with very low [[efficiency]].
So, these devices can mostly be classified as low-power, low-efficiency energy converters (not free energy producers) which are able to use low grade energy sources, but which would be impractical or impossible to use at a large scale for mass energy production, as efficiency would be extremely low, as well as power output – if any.
Some examples of real such devices include:
*The [[drinking bird]] toy (the energy comes from small ambient temperature gradients and evaporation, and harnessing the small power output would likely disrupt the working cycle).
*A [[capillarity]] based water pump: in this case, energy would again come from small ambient temperature gradients and [[vapour pressure]] differences, although it would be far too easy for the pump to stop functioning.
*A [[Crookes radiometer]], a partial vacuum glass container with a lightweight propeller moved by (light-induced) temperature gradients.
*Any device picking minimal amounts of energy from the [[electromagnetic radiation]] around it. Some modern [[Radio Frequency Identification|smart labels]] (RFID chips) actually work based on that principle, using the same electromagnetic field used for "reading" them as their powersource.
* In the [[Atmos clock]] the vapor pressure of ethyl chloride changes with temperature and winds up the clock spring.
Some examples of imaginary such devices:
*A [[ship]] or a large power plant using the temperature gradient and heat transfer between a large surface exposed to the sun (or another heat source) and a colder one (e.g., the [[sea]] or the ground). This would actually be a low-efficiency solar generator, far less efficient than conventional [[solar cells]].
*Any other similar device using a combination of small temperature gradients, [[heat pipe]]s, [[evaporation]], [[phase transition]]s, solar energy, electromagnetic radiation etc.
In all of these cases the "free" energy would, in any case, come from "lesser" forms of energy already present in the environment in small quantities, and the net power outputs would be extremely small to build a large-scale generator. While it certainly is possible to convert some of the ambient's low-grade heat into useful work, that would not be, by definition, "perpetual motion", and the efficiencies are so low that such devices can only be used as [[toy]]s or [[novelty item]]s.
==Ubiquitous energy from atomic and chemical bonds==
{{See also|Activation energy|Entropy|Thermodynamics}}
All working energy devices require either a heat reservoir (such as [[solar radiation]]) or a process of utilizing dense stores of energy (such as [[nuclear energy]] or [[chemical energy]]). [[Heat pumps]] are capable of transporting this waste heat in excess of the heat used to run them (cf. [[Coefficient of performance]]>1), but are not perpetual motion machines because the transferred heat is part of the input.
Conventional sources of energy such as [[petroleum]] and [[natural gas]] or radioactive materials such as [[uranium]] rely on a small fraction of the inherent and ubiquitous energy of atoms and molecules, although the energy of atoms and molecules are not characterized by an internal temperature. Electrical power plants can only be profitable by extracting the nuclear and chemical energies in excess of the energy needed to:
* locate and mine the construction materials, process them into usable form (concrete, steel), and build the plant
* locate, mine/extract, transport, purify, concentrate, and react the fuel materials
* operate the plant in a safe and stable manner
* repurify uranium waste back into usable fuel
* decommission and dismantle the retired power plants
Scientists are currently spending many research hours in attempt of getting more power out of [[nuclear fusion]] than what it takes to run the power plant. If solved, nuclear fusion would supply the world with an abundant source of electricity. The entire [[energy industry]] relies on a system where thermal output exceeds the thermal input. When determining the present thermal output that exceeds present thermal input, one only considers the time during which the energy of the fuel is consumed, and not the time during which the energy was stored in that fuel.
==Examples==
* '''[[Motionless Electromagnetic Generator]]''', a device that supposedly taps [[vacuum energy]].
* '''[[Perepiteia]]''', a device that claims to utilize [[back EMF]].
* '''[[Steorn]]''' Ltd., a company that claims to have built a motor using only permanent magnets.
* '''[[Stanley Meyer's water fuel cell]]''' A device that purportedly [[Water-fueled car| powered a car]] by converting [[Electrolysis of water|water into hydrogen]] and harnessing the energy of hydrogen combustion (which, in turn, emits water vapor that can be refueled to the car)
=== Gallery ===
This is a gallery of some of the perpetual motion machine plans.
<gallery>
Image:Perpetuum1.png|The "Overbalanced Wheel". It was thought that the metal balls on the right side would turn the wheel because of the longer lever arm, but since the left side had more balls than the right side, the torque was balanced and the perpetual movement could not be achieved.
Image:Prepex2.svg|The "Float Belt". The yellow blocks indicate floaters. It was thought that the floaters would rise through the liquid and turn the belt. However pushing the floaters into the water at the bottom would require more energy than the floating could generate.
Image:Boyle'sSelfFlowingFlask.png|The "Capillary Bowl". It was thought that the capillary action would keep the water flowing in the tube, but since the cohesion force that draws the liquid up the tube in first place holds the droplet from releasing into the bowl, the flow is not perpetual.
<!-- Unsourced image removed: Image:Sandwheel.gif|The "Sand Tube Magical Wheel". The black parts indicate sand. It was planned to be a replacement after the original [[Magic wheel]] failed. It works with the same theory of the original wheel, and ends up the same. -->
</gallery>
== Free energy suppression ==
{{Main|Free energy suppression}}
Self-taught inventors exploring the topics of perpetual motion are often highly secretive of their work and unwilling to openly discuss what they are doing, instead offering only limited-access demonstrations without explanation or documentation. They claim to do this for a number of reasons:<ref>A Youtube video that covers all the conspiracy bases: ''Free Energy - Pentagon Conspiracy to Cover up'' http://www.youtube.com/watch?v=uGRsQZx6zWA</ref>
* They are afraid their potentially highly valuable idea will be stolen.
* They are afraid of physical violence from disrupting the business of established energy providers.
* They are afraid of the military declaring their work top secret and confiscating the work for military application or weaponization.
* They are afraid government agencies shut them down to preserve taxes.
==Perpetual motion in popular culture==
{{Trivia|date=May 2008}}
*In [[Mark Helprin]]'s ''[[A City In Winter]]'', a clock tower's machinery, constructed of jewels and precious gems, is stated to be a perpetual motion machine, given by [[God]].
*The Selenite power station in the 1964 adaptation of H.G. Wells' ''[[First Men in the Moon]]'' is purported to be "Perpetual Motion – if it weren't impossible…".
*In "[[The PTA Disbands]]" episode of ''[[The Simpsons]]'', Lisa builds a perpetual motion machine when there was no school due to a teachers' strike; after seeing the machine, her father Homer says: "This perpetual motion machine Lisa made is a joke, it just keeps going faster and faster," and afterwards yells at her saying "Lisa, get in here…In this house, we obey the laws of thermodynamics!"
*In the Playstation 2 video games [[Xenosaga]] I & II, and in the Playstation 1 video game [[Xenogears]], the device, called the Zohar, is a form of a perpetual motion machine. It is briefly described as a ''Pseudo-Perpetual Infinite Energy Engine''.
*[[Thomas Pynchon]]'s ''[[The Crying of Lot 49]]'' includes the description of a suggested perpetual motion machine, along with an explanation as to why it doesn't work.
*In the [[computer game]] ''[[The Sims]]'', a complex (and very expensive) perpetual motion machine can be bought as a household decoration. No devices are available, however, to harness it to do any work.
*In the [[computer role-playing game]] ''[[Ultima VI: The False Prophet]]'', a perpetual motion machine is on display in the museum in Britain.
*One episode of the [[Nickelodeon (TV channel)|Nickelodeon]] program ''[[Invader Zim]]'' showcased a Perpetual Energy Generator (or as its creator likes to call it, PEG) that is never activated due to the impatience of a member of the crowd present at the activation ceremony.
*In episode 16, The Great Sandcastle Race, of the [[Nickelodeon (TV channel)|Nickelodeon]] animated series, [[Rocket Power]], one group makes a perpetual motion machine instead of a sandcastle.
*In [[Disney]]'s ''[[Recess (TV series)|Recess]]'', one episode shows Gretchen Grundler creating a perpetual motion machine for her science project. Upon her demonstration to the class, a team of government agents photograph the blackboard equations, confiscate the model, and remove evidence of its existence.
*A perpetual motion machine was featured in episode 10 of the [[anime]] series ''[[Cowboy Bebop]]'', "[[List of Cowboy Bebop episodes|Ganymede Elegy]]". It is repeatedly seen in Alisa's bar, La Fin.
*In 2006, the [[Drum Corps International|DCI]] corps, [[Santa Clara Vanguard]], performed a show entitled "Moto Perpetuo," based on the theme of constant movement in music and drill.
*In the fighting game ''[[Tekken]]'', character Bryan Fury has a perpetual energy generator built within him by Doctor Boskonovitch which grants him unlimited power.
*In the [[Creedence Clearwater Revival]] song, "Up Around the Bend", the third verse begins, "You can ponder perpetual motion."
*In [[Terry Pratchett]]'s ''[[Thud!]]'', the Dwarves have "devices" called "axles," which appear to be some kind of perpetual motion device, turning with no apparent way to stop them.
*In the [[Kurt Vonnegut]] novel [[Hocus Pocus]], the main character, an instructor at a school for learning-disabled youths, gets his class to attempt the creation of perpetual motion machines. After they experience sundry failures, he places the devices on display for the public, under a banner that caustically reads: "The Complicated Futility of Ignorance."
*In ''[[Angels and Demons]]'' by [[Dan Brown]], one plot hinge is that a Catholic scientist succeeds in verifying Genesis by creating quantities of matter and antimatter out of nothing, for an energy input far less than the amount of mass created — so that annihilation of the antimatter would yield a vast amount of energy. This has been debunked by [[CERN]]<ref>[http://public.web.cern.ch/Public/Content/Chapters/Spotlight/SpotlightAandD-en.html CERN - Spotlight: Angels and Demons<!-- Bot generated title -->]</ref> as constituting a perpetual-motion device.
*"[[The Last Question]],", a short story by the late [[Isaac Asimov]], is concerned with the reversal of entropy — in effect, perpetual motion.
*"The Billiard Ball," a short story by the late [[Isaac Asimov]], contains a device which neutralizes the mass of objects within its field, so that they are thus compelled to instantly attain the speed of light − part of the energy subsequently extracted from them is fed back to maintain the field.
*"Brown Shoes," a short story by the late [[Theodore Sturgeon]], describes a man's elaborate preparations to get the world to accept and use his perpetual-motion device.
*In the science fiction novel [[Pushing Ice]] by [[Alastair Reynolds]] spinning wheels are constructed and placed over areas of the moon where the local gravity is greater than that of the surrounding area. With the wheels half over the area and half not. This causes the wheels to spin perpetually providing energy
*[[Matthew Reilly]]'s novel [[The Six Sacred Stones|Six Sacred Stones]] features several diamond pillars created by a pre-human civilization. One of these eventually 'reveals' the secret of perpetual motion (as discovered by this civilization), or limitless energy, but it is never explained in the book.
*[[Perpetual Motion Machine]] is the name of a jazz/funk/blues quintet from Long Island, New York, USA.
*In the [[Gundam 00]] anime, a GN Drive is a Semi-Perpetual motion generator that installed in the Gundam mobile suits that generates special particles called GN Particles. It can run for an unlimited amount of time and creates an inexhaustible amount of energy for the use of the Gundam. It is mentioned that it can only be constructed in Jupiter's atmosphere using topological defects and the time needed is possibly decades leaving mass production out of the question. It differs from a GN Drive Tau which can run for a limited amount of time before needing to be recharged but can be mass produced more easily.
*In the [[Southland Tales]] by [[Richard Kelly]] a machine which produces "fluid karma", an inexhaustible energy supply, is said many times throughout the film to be a perpetual motion device.
==See also==
* [[John Ernst Worrell Keely]]
==Notes==
<references />
==External links==
* {{cite book
| author=[[Veljko Milković]] and Nebojša Simin
| url=http://www.veljkomilkovic.com/KnjigeEng.html#perpetum
| title=Perpetuum mobile
| publisher=Novi Sad (Serbia), Vrelo
|date=2001
}}
* {{citation
| last=Schadewald | first=Robert J.
| title=Worlds of Their Own - A Brief History of Misguided Ideas: Creationism, Flat-Earthism, Energy Scams, and the Velikovsky Affair
| year=2008
| publisher=Xlibris
| isbn=978-1-4636-0435-1}}
* [http://energie.noosblog.fr Perpetuum Mobile]
* [http://www.youtube.com/watch?v=us7YB7eiOeQ&mode=related&search= Perpetuum Mobile] Video.
* [http://www.galleri-finsrud.no/sider/mobile/foto.html Perpetuum Mobile] Site.
{{Sisterlinks|Perpetual motion}}
===Historic===
* [http://www.lhup.edu/~dsimanek/museum/unwork.htm The Museum of Unworkable Devices]
* Donald Simanek's [http://www.lhup.edu/~dsimanek/museum/people/people.htm History of Perpetual Motion Machines]
* Richard Clegg, "''[http://www.richardclegg.org/new/musings/perpetual.html Perpetual Motion Page]''", richardclegg.org.
* [http://www.lhup.edu/~dsimanek/museum/overbal.htm A selection of Bhaskara-like devices]
===Research===
* [http://www.kilty.com/pmotion.htm Kevin Kilty's perpetual motion page]
* [http://high-inventions.blogspot.com Abbas Shafiee's perpetual motion page]
* Vlatko Vedral's [http://xxx.lanl.gov/pdf/0707.3400 Lengthy discussion of Maxwell's Demon] ([[Portable Document Format|PDF]])
===In Popular Culture===
* An Israeli [[juggling]] act named ''[http://www.lulyanim.com "Perpetuum Mobile"]''.
*[http://www.myspace.com/pmmmusic "Perpetual Motion Machine"] - Jazz/Funk/Blues quintet from Long Island, NY
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[[Category:Perpetual motion machines| ]]
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