Talk:Perpetual motion

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I just found this on the page. I take it that osmosis can not produce perpetual motion, so this passage is being deleted

Osmosis causes water particles to move from an area of higher concentration to an area of lower concentration. So in an u-shaped cylinder with a partially permeable membrane in the middle, the water level of one side will be higher than the other side. Then when the water level reaches high enough you put a bridge between the two and put another membrane in the middle, and the water will flow to the other side. Perpetual Motion is therefore achieved.

My problem with this is that you have to put a bridge between the two and put another memberane in the middle. Thus, it is not self-sufficient.



[edit] Reversion

I made a number of (what I considered to be) corrections and clarifications to the article on 2005-12-13. User:Reddi performed a wholesale reversion, without comments, an hour later. Reddi, why did you do this, please? Gareth McCaughan 00:29, 15 December 2005 (UTC)

You deleted alot of relevant content. J. D. Redding 15:52, 15 December 2005 (UTC) (PS., here is the ed diff ... please list the "much tidying" points, the way of "reorganization", and point out what is to be "cleaned up". Thanks.)

I deleted some mistakes and repetitions. I attempted not to delete anything that added value to the page unless I was also adding something that added the same value at least as effectively. One of my goals was to improve the focus and conciseness of the page. Here's a summary of what I did and why.

  • Deleted last sentence of initial para ("Note that constant motion ...". This material was incorrect (really constant motion would be PM "of the second kind"; the Earth-Moon isn't truly constant because there is dissipation in the system) and redundant (with discussion elsewhere in the page of friction, dissipation, second law of thermodynamics, etc.); it's especially redundant with one of my additions noted below.
  • Deleted first sentence under "Introduction" ("There are two subcategories ..."). This material was redundant with the later description of the classification of PMMs, and there's no way that the existence of a two-way classification is a good candidate for the first thing to be said in an introduction to the topic of PM.
  • Moved the remainder of that paragraph ("Scientists and engineers accept ...") to later in the article. This material was misplaced, being (in my opinion) not in any useful sense an introduction to the topic but rather a discussion of some issues arising from it.
  • Moved the following paragraph ("Serious discussions of perpetual motion ...") to keep it together with the moved material from the previous paragraph.
  • Deleted the next paragraph ("In short, the entire reason ..."). This material was incorrect (perpetual motion is not "possible in theory" in any useful sense, and friction is not the only reason why it's impossible; "negative change in velocity" doesn't make sense) and redundant with added material about PMMs of the second kind later on.
  • Moved a paragraph mostly about the second law of thermodynamics ("Perpetual motion machines violate ...") to nearer the start of the article.
  • Moved the following paragraph ("Machines which claim not to violate ...") to nearer the start of the article. These two paragraphs make a much better introduction to the subject than the earlier muddled "introduction" (I'm excluding the very first paragraph, which I've basically left unchanged because it's pretty good).
  • Added a new one-sentence intro to the first/second kind classification.
  • Rewrote the explanations of "first kind" and "second kind". The old material was incorrect (a machine producing just "at least as much energy as it uses" need not violate conservation of energy; a PMM of the second kind need not convert heat into other forms of energy) and contained irrelevancies (the fact that many PMM designs use magnets, and the fact that a PMM of the second kind would be viewed with skepticism, do not help in understanding the distinction between the two kinds), and was ungrammatical (the explanation of the "first kind" ended "... and assume frictionless .", presumably because of a mouse-slip at some point).
  • Added a paragraph about friction, dissipation, and so on. This replaces various material in the old version (friction, good approximations to PMMs of the second kind, Earth/Moon system, single particle in a Newtonian universe), bringing related things together in a relevant context. It does this more accurately, and using considerably fewer words, than before; and, I think, with just as much clarity.
  • Added a section called "Just how impossible is impossible?", which is where the material about scientists' attitudes to PMMs and to the laws of physics moved to.
  • Deleted an incomplete and inaccurate definition of "perpetual motion machines" from the "Inventions and patents" section. This material was redundant (there are definitions earlier in the article) and misplaced (a definition of PMM doesn't belong buried in a section on inventions at the end of an article on PM) and incorrect (a PMM need not "produce useful energy").

I think that's all the changes I made. I had (what I considered, and still consider, to be) good reasons for all of them. So far as I can see, no useful information was lost and no viewpoint skew was introduced by my changes; I think the article became shorter, more accurate, better organized, and clearer. Of course your mileage may vary.

Now, would you care to explain what about my changes justified a blanket reversion without comment? Thank you. Gareth McCaughan 01:33, 16 December 2005 (UTC)

These arguments appear conclusive to me. I've recverrted to Gareth's version. --Pjacobi 08:21, 16 December 2005 (UTC)

First off, I will apologize for the blanket reversion ... I may have jumped the gun (mabey the radical change was a bit jarring to me) ... your version is an improvement (atleast as to the focus). It does seem that you did not attempt to delete all relevant content (some content though should be readded). And thank you for the a summary of what was done and why. Below is some of the point that I would like to point out on the revamp of the article ...

  • It would be nice to address "some mistakes" in the article more fully and keep some of the repetitions, though. YMMV on the "more accurately" and the "clarity" ... and it is not necesssary to use "considerably fewer words" (Wikipedia is not paper; an article _should go indepth_, not be "concise" [an editorial preference for expressing ideas in just a few words]). Some information is necessarily "redundant" (eg., useful repeated or duplicated information).
  • adding of the one-sentence intro to the first/second kind classification. It was "There are two subcategories of perpetual motion machines which are referred to as perpetual motion of the first kind and perpetual motion of the second kind" and you changed it to "It is customary to classify perpetual motion machines as follows [the 2 types]".
  • The rewrite of the the explanations of "first kind" and "second kind" is good. But ... mabey an explaination in the articel on how incorrect the statemnet "A perpetual motion machine of the first kind produces at least as much energy as it uses, Therefore, once started, the machine could go on forever, which appears to violate the law of conservation of energy" is ... you changed it to: "A perpetual motion machine of the first kind produces strictly more energy than it uses, thus violating the law of conservation of energy." I think it comes down to the "at least as much energy as it uses", and your redefition excludes "PPM" that do so (as you state, such a machine need not violate conservation of energy ... but that is why the "appears" is there).
  • You deleted relevancies (which may have not been appropriate at the section they were at ... but is appropriate to the article in general) ... the fact is that many PMM designs use magnets (eg., Many of first kind designs utilize magnets as some kind of free energy source and are assumed to be frictionless), and the fact that a PMM of the second kind would be viewed with skepticism.
  • Moving the remainder of that paragraph ("Scientists and engineers accept ...") to later in the article was good ... but the rewrite removes some relevant material of the original (it is, thjough, kinda hard to tell when such a drastic change in format as in your edit).
  • Deleting the next paragraph ("In short, the entire reason ...") was not too good. All this material is not incorrect ... perpetual motion is "possible in theory" ... it may not be practical (eg. useful), though ... but that is entirely another point.
  • As to the deletion of the "If friction were removed (which is impossible) then perpetual motion would be possible" ... mabey a list of reasons why it's impossible ... and the later potions of "negative change in velocity" is a part of kinematics and acceleration, this could be expanded ...
  • The section called "Just how impossible is impossible ?" should be renamed.
  • Deleted an accurate definition of "perpetual motion machines" from the "Inventions and patents" section. This material is not redundant. A definition of PMM as reguard to patent does belong in a section on inventions. "Perpetual motion machines are a class of hypothetical machines which produce useful energy "from nowhere" - that is, without requiring additional energy input." It's only incorrect if you set up the defintion to exclude such machines ... I also believe that this is from the USPTO website.

The overall revamp of the article was good ... and, again, I do apologize that I jumped the gun. I also do appreciate that you took the time for a summary of what was done and why. I'll go though the diffs in the history and look at it more closely though at a later time. Thanks again. Sincerely, J. D. Redding (PS., a section on so-called "PPM" that do not violate the laws should be made ... not all PPM brake the law of thermodynamics, the "cox timepiece" is one example ... some devices are just called "perpetual motion machine" ... )

Taking those points in order:

  • Indeed, having fewer words is not an improvement if it means having less information. I don't think I lost any useful information, though I gather you disagree. If you're right, the problem is with my judgement of what's useful, not with my preference for brevity when it can be attained without loss of information :-).
  • I'm not sure what it is you don't like about the slightly changed lead-in to the classification. If you mean that I forgot one change in my list, then I plead guilty. I still think it was a good change...
  • A PMM that produces exactly as much energy as it uses is a PMM of the second kind, not the first; the problem isn't that it violates conservation of energy but that it violates the second law of thermodynamics. Or, if you can cook up a situation in which it needn't do so -- such as that single particle moving in an otherwise empty Newtonian universe -- then indeed that would be a working "perpetual motion machine". I've added a sentence to the definition of a PMM of the first kind, which may clarify this relationship between the two. Maybe there's a better way to make it clearer.
  • I still don't see what value there is in the isolated observation that many PMMs use magnets. However, I do see some value in a more general discussion of approaches PMM inventors have tried, and I've added one. It could use some expansion.
  • It isn't necessary to say separately that a second-kind PMM would be greeted with skepticism, because it's already been clearly pointed out that any PMM would be greeted with skepticism. (If anything, a second-kind PMM would be met with less skepticism than a first-kind one.)
  • What relevant material was removed in moving the "Scientists and engineers accept ..." paragraph?
  • I stand by my claim that the paragraph about friction being the only problem with PM, and about its being "possible in theory", was just plain wrong. There were some right ideas underlying it (dissipation, although not limited to friction, certainly includes friction as a special case; a second-kind PMM is not forbidden by the most fundamental laws even though it is -- yes, in theory! -- impossible in the real universe), but I think those are present in the revised article.
  • I'm not sure what you're proposing doing with the thing about "negative change in velocity". Extracting work from a moving object requires that it slow down (er, or lose mass) -- but that's there in the revised version already. The only difference between "without slowing it down" and "without a negative change in velocity" is that the latter sounds more technical but doesn't actually make sense (because velocity is a vector).
  • I don't much like the title "Just how impossible is impossible?", but I haven't yet been able to think of a clearly better title. If someone else can do so, I'll be glad.
  • I agree that there may be some benefit in saying in the "inventions" section what the USPTO's definition of perpetual motion is -- but only if it's explained that this is specifically the USPTO's definition, and only if it actually is their definition or at least an abridgement of it. I've done a bit of googling but not turned up anything specific enough to be useful here; maybe someone else will do better.
  • I agree that it could be useful and interesting to have a section about things that are called "perpetual motion machines" but don't violate the laws of physics. I worry that it might encourage people who want to use the article to expatiate on their own pet schemes that do (unbeknownst to them) violate the laws of physics. Cox's timepiece is already mentioned explicitly in the article (in the "inventions" section) with a note that it doesn't actually violate any laws.

Gareth McCaughan 23:28, 16 December 2005 (UTC)

[edit] 2nd kind

Perhaps I'm getting something wrong, but the current definition of 2nd kind ppms looks strange to me. If it all, what is described there is a borderline case (and perhaps perpetual motion without excess energy to solve the world's energy problem should be handled seperately). In my understanding a 2nd kind ppm converts heat into mechanical or electrical energy. Not by a carnot process but just some reservoir gets cooler. The claimed observation that the apparatus or the environmental air gets cooler is sometimes seen as sign, that over-unity operation has been achieved [1]. --Pjacobi 23:49, 16 December 2005 (UTC)

I've seen the definition of a PMMOT2K phrased in multiple ways, all of which amount to "machine that violates the second law". I think the "heat into work" definition is commonest, but the reason why a machine that converts heat into work is called a perpetual motion machine at all is that you could use it to make something that runs for ever without running down. Unfortunately, if you just say "heat into work" you're likely to get objections about the (perfectly straightforward and commonplace) machines that convert a heat difference into work; tightening the definition up seems inevitably to produce either something too specific (e.g., requiring a cyclic process) or something that's verbose or unclear or both. On the other hand, there are two distinct ways to make a machine just run for ever: a complete avoidance of dissipation (on which the existing text focuses) or a means of reversing it (which is really the main point of a PMMOT2K). So I've made some adjustments. See what you think; it's surely still possible to do better. Gareth McCaughan 09:00, 17 December 2005 (UTC)

[edit] Just how impossible is impossible?

[edit] Moved from article

Serious discussions of perpetual motion usually occur only when dealing with the topics of open systems, aether theories, free energy, and vacuum energy.

A machine that spins for thousands of years might do useful work without fuel, work, or maintenence cost, much like spinning planets and electrons already do naturally. If the spinning object spins very strongly, any work benefitted from it would slow it down slightly, but a fraction of a second later, the magnetic/gravitational pull would cause it to continue its spin at the same speed as before it slowed.

"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 machinary," ---- Nikola Tesla. This sounds similar to the use of natural currents of matter to push and turn wheels to perform useful work, like in windmills and water wheel mills. Windmills and water mills are near-perpetual motion machines because they continue to move/turn for manty years withou fuel or batteries until the machine parts wear out, wind stops blowing, or the river dries up.

Mainstream science tends to lump perpetual motion and near-perpetual motion together, in a belief that it is impossible. However, science is constantly learning new facts and physical secrets at a quick pace. At one time, all mainstream scientists were certain that an object heavier than air could not fly; the law of gravity made this a scientific certainty. Today, airplanes weighing tons fly faster than the speed of sound. The law of gravity was not broken - it is impossible to break a law of physics. Instead, new laws of physics were discovered: laws of lift, drag, speed, and aerodynamics. These new forces countered and exceeded gravity's force. In similar ways, many other laws of nature can countered by other opposing physical forces. In the future, it is likely that scientists will do things that are certainly impossible by the pysics of today. So, perpetual motion is impossible by our modern technology, but may not be impossible by future technology.

[edit] Discussion

This section has one and a half main problems:

  1. Serious: The question of near-perpetual motion is possible, but you cannot extract siginificant work from it - that would end it's near-perpetual motion.
  2. Stylistic: The lamenting about new things possible discovered in the future

Pjacobi 23:57, 14 January 2006 (UTC)

If such a thing could be duplicated in a lab, man-made near-perpetual motion could become a reality.

Aren't the voyager space probes examples of man-made near-perpetual motion? Bobby1011 19:29, 6 February 2006 (UTC)

[edit] Copyedit Tag

Some parts of the article are written in poor English and are too ambiguious to make sense of. I'm too tired to fix it up right now so, I'm leaving this tag. Bobby1011 19:47, 6 February 2006 (UTC)

Could you point to specific sections? Many of the concepts discussed in this article are difficult to describe, but hard to understand doesn't always mean bad writing. KarlBunker 21:00, 6 February 2006 (UTC)
While we're waiting for further input, I'll remove the copyedit tag. I read through this article and didn't find it to be poorly written or ambiguous. KarlBunker 01:29, 7 February 2006 (UTC)

[edit] WMC POV edit

WMC editing in a POV fashion ... "prefer the version before Reddi's fiddling".

The content is not in dispute ... but it is a POV edit and violation. J. D. Redding 21:08, 10 March 2006 (UTC)

Please don't be silly. You've added nothing useful, but increased the number of words, adding dups re friction and nonsense such as Atmospheric electricity is the regular diurnal variations of the Earth's atmospheric electromagnetic network (or, more broadly, any planet's electrical system in its layer of gases). William M. Connolley 21:49, 10 March 2006 (UTC)
If "silly" is the only thing you can say ... it's sad ... do you know that it's cited for perpetual motion (and near-perpetual motion machines ...)
Atmospheric electricity is used often in these machines ... but need coils and structures to utilize them as the patents state in the articles (this dates back to 1860s for heaven's sake) ... and historians of technology know this ...
Telluric currents are often used in these machines ...
Atmospheric changes are often used (and don't mention the second part, that you need a barometer!!!) ... the Cox timepiece was a near-perpetual motion machine (commonly known if you liik and read a damn book on it) and this technique done before the timepiece itself independently discovered ...
ZPE, Vacuum energy, and Quantum Flux is purported technique commonly cited recently ...
You hurt wikipedia by POV pushing and removing ("prefer" to obfusacate the) facts ) .... if you cannot "debunk" the claims ... don't remove them because you don't like the facts ... as you repeatedly do. J. D. Redding 03:06, 11 March 2006 (UTC) (... not an ignorant fuq of the history; read a bit of history sometimes ...)
Reddi, you are wiki's most notoroius POV pusher of psuedoscience, so much so that you've managed to get an arbcomm judgement restraining you - happily for all the rest of us William M. Connolley 11:29, 11 March 2006 (UTC)
Attack the messenger ... ignore the discussion points ... nice ... J. D. Redding (PS., facts are "not made" by concensus)
Where do magnets come into play? Are they considered an external power sources or just too easy? I mean, really. A wheel with several magnets spaced at regular intervals powered by a nearby magnet would probably rotate forever... and it wouldn't catch on fire or violate the laws of thermodynamics if you stopped it manually every once in a while... later.

-Willis

It's hardly perpetual if it requires outside intervention to keep working. And no, magnets do not produce the kind of perfect motion required for such a wheel to maintain velocity ad infinitum. --Agamemnon2 10:44, 21 June 2006 (UTC)

Ahh But if you were to set up a heavy magnetic ball and attach it to a wheel, when the wheel turns it turns some gears sorta like a turbine the power coming from that charges an electro magnet up the top of the wheel, this brings the ball back up to the top, when the ball gets to the top it stops moving which cuts off the power to the electro magnet ball falls down again. Process repeats. Not bad for a high school student eh ?


You didn't sign your comment, and your suggestion doesn't work. The process of getting power from the wheel is less than 100% effective. The process of feeding the power to the electromagnet is less than 100% effective. So, in the end you have less energy than is needed to get the ball back to the top (you would have to add energy for that). So, as Agamemnon2 pointed out this isn't perpetual motion. (Although I note the gullable add money to schemes like this all the time...) |Nahaj 20:00, 26 June 2006 (UTC)
Nahaj makes a good point. Would it be out of place to include in the article mention of the many perpetual motion scams? --MrFlit 15:33, 27 June 2006 (UTC)

[edit] Illustrations

Could we get more pictures on this page? It would be enriched much more by diagrams. Minglex 10:18, 1 May 2006 (UTC)

[edit] Drinking bird

Needs a reference to the "Drinking Bird". I recall some free/alternate energy board discussion about using many thousands of these toys -- or perhaps just one, but a hundred feet tall -- to generate electricity. Sans feathers and top-hat, of course. -Wfaxon 07:27, 9 July 2006 (UTC)

[edit] Superfluids?

superfluids flow endlessly (among other odd behaviors). If one can maintain the superfluid, one can maintain a state of zero friction/viscosity and no energy is wasted through motion. These properties are actively used in high precision measurement.

Now, arguably this is not a "perpetucal motion machine" in either of the classical definitions put forth in the article. It does not produce energy from nothing, and it does not convert waste energy back into useful energy (as there is no wasted energy in a flowing superfluid or supersolid).

Not to stir up any trouble, but these sort of weird quantum phases of matter probably deserve mention somewhere on the page.

(oops, forgot a signature) - Toastydeath 05:12, 30 August 2006 (UTC)

I know it's hard to believe, but me and many scientists have discovered how to use superfluids to make electricity through fluid turbines. We are currently accepting donations...

[edit] Latest scoop

A couplee of days ago in the British Times newspaper, there was a report of an engineer claiming he had discovered a perpetual motion machine. When the reporter asked to see it, he was refused admission. THe inventor has decided to patent it before releasing details, but he said it worked by an magnetic field 'anomolaly' that he has just discovered!. Can we mention this in the art as it is from a reliable source?--Light current 00:36, 31 August 2006 (UTC)

[edit] John Galt's motor?

The device in Ayn Rand's novel Atlas Shrugged works by drawing static electricity from the air. Would that qualify to the "Perpetual motion in pop culture" section? - Stormwatch 06:38, 31 August 2006 (UTC)

I don't think so - such a machine depends on there being electrical gradients in the air, and is therefore ultimately solar-powered. Tevildo 23:06, 13 January 2007 (UTC)
This would fall into the "apparent perpetual motion machines" category. EpiVictor 12:17, 14 January 2007 (UTC)

[edit] Removed bit about MythBusters

I removed this:

The Discovery Channel program MythBusters attempted to build a perpetual motion machine consisting of several propane tanks arranged in an overbalanced wheel, supposedly to draw energy from a heat difference between two ends of the device (with the lower end moving through water heated by the sun). Technically it did work, but its movement was barely perceptible and created so little electricity the hosts declared it a failure. Since it relied on the sun to heat the water beneath it, the device was essentially an overly complicated solar power generator. They also examined other methods of gathering "free energy". These methods generally failed, were not cost-effective, or were too unwieldy to be feasible. They did generate a spark that zapped one of the show's hosts during the investigation of a radio based device.

for the very simple reason that it's not a perpetual motion machine - it's a very inefficient heat engine taking advantage of the difference in temperature between the heated water and the ambient air. --Robert Merkel 09:09, 31 August 2006 (UTC)


[edit] Definition

I think we need a new definition at the top of the article. Since you cannot prove that something will continue *forever*, you don't need any law of thermodynamics to prove that nothing can possibly satisfy the definition as is. Dave 20:15, 15 September 2006 (UTC)

[edit] Lutec overlooked

Lutec Australia Pty. Ltd.[2] have a perpetual motion concept based on magnets which they claim will manufacture over-infinity production of electricity, perhaps worth a look for this article? Jachin 23:11, 3 October 2006 (UTC)

Specific claims go into history of perpetual motion machines, but only if reliable third party sources can be found. --Pjacobi 08:20, 4 October 2006 (UTC)
Over infinity. Good thing it doesn't work, it would blow up the Earth! And that's where I keep all my stuff! Maury 15:40, 14 January 2007 (UTC)

[edit] Abrupt gravity field changes?

An interesting hypothetic case would be moving a body in and out of two nearby regions of space with markedly different (or even of opposite directions) gravity, by producing useful work by letting the weight to be "pulled down" in the high gravity region, and "pulling it up" in the low or reversed gravity region, while sliding it between regions would be done with a motion perpendicular to the gravity force lines, thus with no (or very little) energy expenditure.

This approach is known not to be possible with electric and magnetic fields, as it's not possible to produce the abrupt field intensity changes required (the distribution of electric and magnetic force lines would arrange itself as to preserve field conservativity in any case, but would something similar happen for gravitational fields too?

I wonder whether something "strange" would happen during the transition from one gravity field to another, e.g. a very rapid gain or loss of energy which would prevent "freeloading", assuming of course it was somehow possible to produce such controlled and space-limited gravity fields. EpiVictor 14:29, 19 October 2006 (UTC)

All inverse square forces, including electricity, magnetism (same thing) and gravity are "conservative". There is simply no way to construct a field layout as you describe. No magic involved, it's like trying to touch your right elbow with your right hand, you just can't do it. Maury 15:35, 14 January 2007 (UTC)
Yes, I know they are conservative and, at least magnetism and electricity cannot be "cheated" because no matter how complex their configuration, they will eventually "close" (magnetism) or terminate on another charge/object (electricity), thus preserving the "conservative" property. But gravity field lines (if such a thing exists) haven't yet been proven to "close" or "bend" like electrical and magnetic lines do, and neither that such extreme configurations are impossible, like two intense and opposite direction gravity fields existing very close and perfectly parallel with each other. Gravity and its propagation methods and field properties still haven't been thoroughly studied and explained, as opposed to electricity and magnetism (it's not even known if it is linked or not to electricity or magnetism) and as a force field, it's in general a lot weaker than electrical and magnetic fields, and it's only manifested macroscopically when generated by large bodies as planets, in a mostly neutral electrical and magnetic environment. EpiVictor 10:05, 16 January 2007 (UTC)
"gravity field lines (if such a thing exists) haven't yet been proven to "close" or "bend" like electrical and magnetic lines do"
Let me repeat myself: all inverse square law forces are conservative. Gravity is an inverse square law force. Therefore it is conservative. Full stop. This isn't due to the nature of gravity, it's a trivial mathematical demonstration. You need to do your homework. Maury 15:14, 16 January 2007 (UTC)

I think if we find a black nearby we could exploit the acceleration of matter into black hole/or radiation given off the acceleration.

[edit] Adding

Ok, if you turn the electricity into motion amplify the motion (big gear besides little gear,) add some grase, throw it into a vacume chamber and turn the motion back into electricity, you will probibly get more electricity

E\Rightarrow M\times(\mho\div\nabla)\Rightarrow E\times(\mho\div\nabla)

Nabla = Bigger gear, M = Movement, E = Electricity, Mho = Smaller gear.

David Knott

David, you need to look up what a gear does. It does not change the amount of energy, it changes the force (or torque) being produced by that energy. Since the process of meshing teeth always has losses, the energy at the end of a gear train is always less than what you put in. Honestly, if it were this obvious, do you really think you'd be the first person to come up with the idea? Maury 15:35, 14 January 2007 (UTC)

[edit] Gravity

The enermy that the gravity have to move should be taken from the Big Bang?


[edit] Entire Universe

Isn't the universe as a whole a perpetual motion machine? Matter and energy cannot enter or leave, and all particles are always moving. Nate | Talk Esperanza! 22:57, 8 December 2006 (UTC)

No. You actually answer your own question in the third word of the second sentence. A perpetual motion machine needs extra energy. Since the universe does not gain or lose any energy, it is not a perpetual motion machine, at least not the kind being discussed here. Yet, the terminology is confusing, particularly if you consider most modern versions often don't even have moving parts. Maury 15:35, 14 January 2007 (UTC)
The Universe is not a perpetual motion machine for a very simple reason: it will eventually "stop". This is the concept of heat death. After a (long) while, all gradients will have been exhausted, so no "interesting" stuff will occur any more. You'll still have some random brownian motion, but nothing from which you might extract some work. The reason is exactly the same as the reason why perpetual machines of the second kind are impossible: the 2nd law of thermodynamics.--Thomas Arelatensis 13:48, 15 January 2007 (UTC)

[edit] Villard de Honnecourt's device

Does anyone see how Villard de Honnecourt's device was supposed to work? It appears to be some sort of variation of the overbalanced wheel, but I don't see the overbalanced! Maury 00:26, 13 February 2007 (UTC)


[edit] Air-powered car

An air-powered car has been presented by the discovery channel. If they can get an air compressor that is powered by the compressed air, it will potentially become a perpetual motion machine, will it not? 71.193.162.2 05:05, 22 February 2007 (UTC)=Dragonryth

And compressed air is compressed by power of compressed air which is compressed by the power of compressed air which is compressed by the power of compressed air.See any inefficiency?

I don't actualy see any point in what you said. Looks like a random cycle of blabber to me. If you actualy watch the episode, you might get what I said.(It's called Futurecar) 71.193.162.2 04:15, 23 February 2007 (UTC)

Compressed air requires around a 5hp motor to compress enough air to do 1hp worth of work. This is part of how you size air compressors when you buy them in industry (for large air tools). So, you are using far, far more "fuel" when you have an air powered car, because you had to do 5x the amount of work you are actually using. - Toastydeath 06:30, 23 February 2007 (UTC)
Compressed air motors have been used, e.g. in torpedoes, where it is used to move pistons or a small turbine that moves the propeller in turn. There are also airguns and compressed air tools, but none of these uses has anything to do with "perpetual motion". Compressed air just works as a "clean" and convenient (for certain uses) energy storage and transfer medium. Compressing air on the other hands requires energy, and there's no way to compress it with 100% efficiency (actually, even 50% efficiency would be an accomplishment), let alone getting more energy out of it than was used to compress it. EpiVictor 01:13, 26 February 2007 (UTC)

[edit] Just how impossible is impossible?

GaylordBumBum 20:46, 4 March 2007 (UTC)Is this an appropriate heading for an encyclopedia?

I don't know if it's appropriate, but it is funny. And on topic? Not sure how much it matters, seeing as 78.24% of the folks who visit this page are just here to insert whatever crackpot scheme they have for perpetual motion. You know, IF I PUT HAMPSTERS IN A BLENDER AND INCLUDE MAGNETS???? WILL THAT WORK1!! kind of thing. - Toastydeath 23:00, 4 March 2007 (UTC)

GaylordBumBum 23:25, 4 March 2007 (UTC)But my point is that it does not appear to be the style of an encyclopedia entry. Can't we use something else?

Sure! What do you want to use? If you have an idea that you feel is more appropriate and still fits the material under the heading, you don't need permission to edit it. Go for it. If someone disagrees, they'll change it back and it will get discussed further here. Chances are, no one will revert you. - Toastydeath 23:37, 4 March 2007 (UTC)

I was the person who put that heading there. I prefer it to the more prosaic title that's there now, but I don't propose to revert it. I suspect it's possible to do better than either. (If you look right up at the top of this talk page you'll see that when I put that heading in I remarked that it's probably possibly to come up with a better one.) Gareth McCaughan 01:17, 26 March 2007 (UTC)

[edit] demons?

"Yet the Second Law is not violated because the demons pay their entropy cost in the hidden (mirror) sector of the world." what the heck is this? should be removed, or at least clarified.

128.189.250.239 00:22, 9 March 2007 (UTC)wilyolio

I find that it's pretty clearly explained farther up as part of the Maxwell's Demons thought experiment, which IS used in physics classes. I didn't write it, but having read the information preceding it, I have no trouble understanding it. - Toastydeath 04:11, 9 March 2007 (UTC)

[edit] Newton's First Law and Constant motion

I think this page should make it clear that constant motion is possible (Newton's First Law), but that an object cannot generate useful energy as it does so. It's a very common misunderstanding that objects slowly run out of 'thrust' until they stop, I think this article should make the situation clearer to non physics experts. Not sure how I can word it though. --Uberisaac 18:07, 11 March 2007 (UTC)

[edit] balancing act

The perpetual motion "ferris wheel" could not work, as it would simply balance itself.

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