Talk:Perpetual motion

From Wikipedia, the free encyclopedia
Jump to: navigation, search
          This article is of interest to the following WikiProjects:
WikiProject Skepticism (Rated Start-class, High-importance)
WikiProject icon This article is within the scope of WikiProject Skepticism, a collaborative effort to improve the coverage of science, pseudoscience, pseudohistory and skepticism related articles on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
 
WikiProject Physics (Rated Start-class, High-importance)
WikiProject icon This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
 
Note icon
This article has been marked as needing an infobox.


Another problematic statement[edit]

As an outcome of the above discussion (I believe), the opening definition now reads much better. However, there is a similar problem at the start of the next section:

"There is a scientific consensus that perpetual motion in an isolated system violates either the first law of thermodynamics, the second law of thermodynamics, or both."

This is simply not true. Perpetual motion (as it is defined in the opening sentence) does not violate any physical laws. 81.157.14.203 (talk) 20:49, 24 September 2014 (UTC)

... though I said that the opening definition read much better, now I am wondering. Is this distinction between "perpetual motion" and a "perpetual motion machine" actually real, or just someone's invention to fudge the wording? (No offence.) Does a "perpetual motion machine" not do "perpetual motion"? 81.157.14.203 (talk) 20:58, 24 September 2014 (UTC)

The issue is really a historical and linguistic one. The term "perpetual motion" from the Latin perpetuum mobile originated in the Middle Ages, before the concept of energy was understood. People tried to build a machine that would turn "by itself", indefinately. The repeated failure of these efforts led to the concept of energy and conservation of energy, which explained why they were unsuccessful. The modern meaning of perpetual motion in physics has expanded beyond a machine that will turn forever. It means a machine that produces more energy than it consumes, in other words a machine that produces energy from nothing (or in the case of a perpetual motion machine of the 2nd kind, one that produces energy from thermal motion at equilibrium). The term is extended to other types of energy than motion; an electrical generator that produces electric energy with no input fuel would also be called a perpetual motion machine.--ChetvornoTALK 00:25, 25 September 2014 (UTC)
The anachronistic term "perpetual motion" has led to an enormous amount of confusion on this page; people bring up examples like the motion of the Moon or planets, and ask "is this not perpetual motion?" The answer is no it's not, because it doesn't produce energy from nothing. These are just examples of motion with very little friction. A moving object only has a certain amount of energy. Every form of motion is subject to some form of friction, which dissipates its energy, so unless it can produce energy from nothing, it will eventually stop moving. For example, the Moon circling the Earth is subject to drag from the thin interplanetary gas as well as tidal deformation, so it will eventually "spiral in" and collide with the Earth. If you want to show that perpetual motion is possible, you have to show that energy can be produced from nothing. --ChetvornoTALK 00:25, 25 September 2014 (UTC)
Thanks, but I stand by my original comments. Firstly, I do not believe that the distinction between "perpetual motion" and "perpetual motion machine" as made in the opening sentence is valid (or widely recognised), and secondly I do not believe that the statement at the beginning of the "Basic principles" section is true, given the definition at the start of the article. Probably we should focus specifically on what should be done to fix these two issues, if it is agreed that they need fixing. 81.157.14.203 (talk) 02:40, 25 September 2014 (UTC)
What exactly is your objection? I don't see that there is much of a distinction being made between the terms. --ChetvornoTALK 03:04, 25 September 2014 (UTC)

Fix, don't delete[edit]

After spending considerable time attempting to clean up the mess that the LEDE had become, I found all my hard work RVed with a nice note about how it was wrong and unsourced. Neither statement was true, but I guess that's why I'm now here, having to ask what precisely was wrong with it so that I can fix those statements and re-implement. Maury Markowitz (talk) 20:01, 18 October 2014 (UTC)

"Perpetual motion, in the strict sense of the term, is both theoretically possible and seen in practice. The galaxies in the universe will move forever, by any practical definition," is something that caught my eye as being incorrect, unless you have a specific definition of "practical definition" in mind. "Runs a long time" is definitely not "perpetual", especially if there are multiple possible end-states, such as heat death of the universe--essentially, their motion was initiated by energy input (Big Bang or something) and will eventually wind up being converted to other forms rather than motion. It's only perpetual in a sense similar to the next discussed ideas, such as hydroelectric power or other beyond-Earth sources. DMacks (talk) 20:42, 18 October 2014 (UTC)
I agree with DMacks. Point taken, Markowitz; I probably should have discussed before reverting. Here are my issues with the rewrite:
  • "Perpetual motion, in the strict sense of the term, is both theoretically possible and seen in practice."
The biggie. Wrong and misleading. Many, many sources state that perpetual motion is impossible. Perpetual motion of the third kind, frictionless motion, which is what is being referred to in the "galaxies" example, is almost possible, but as has been discussed many times on the Talk page, is not actually possible because it is not possible to have motion without some friction or energy loss.
  • "The exact nature of the failure of these devices was different in every case - the endless waterwheel fails for different reasons than the overbalanced wheel"
This is misleading for nontechnical readers. The most important fact in this article is that all perpetual motion machines fail for one or the other of the same two reasons: They either violate conservation of energy (the first law of thermodynamics) or the second law of thermodynamics. These points should be up near the top. The quote above encourages the common view that all it takes for perpetual motion is for someone to find a better linkage or a different method. Maybe instead make the point that the fact that so many different designs failed led Enlightenment scientists to the idea that a general principle was involved - conservation of energy. Plus the readers haven't been told what a "endless waterwheel" or "overbalanced wheel" is.
  • "...a device that continues to operate with no external inputs while producing useful work"
What kind of "inputs"?
  • "Designs for such devices were popular for centuries..."
I feel this wording may be misinterpreted to mean the ancients had the "secret".
  • "Many perpetual motion machines fail because the design inherently requires more energy to run than the system contains..."
This should be reworded; a perpetual motion machine of the first kind requires an "infinite" amount of energy.
  • "More modern designs, especially those that do not provide physical motion directly, tend to be based on the conversion of energy from one form to another."
Something should be said here about heat or thermal energy; the defining characteristic of perpetual motion machines of the 2nd kind is that they convert thermal energy to work. Also I wouldn't say they were "more modern designs" but that they are a different class or type because they fail for a different reason.
--ChetvornoTALK 23:00, 18 October 2014 (UTC)
Many, many sources state that perpetual motion is impossible Sources talking about perpetual motion machines'. If you do not believe the galaxies are in perpetual motion, you might want to read up a bit more on dark energy. As to "practical definition", anyone can state that anything is not "perpetual" because it had a beginning in time, yet such a definition is not practical. A practical definition would have to include provisions for the time that the device starts and may be deliberately stopped. But adding such distinctions is precisely the sort of overcomplicating that confuses more than
This is misleading for nontechnical readers. I say the exact opposite. The Browning Ratchet doesn't work because of the 2nd law, that simply tells you that you're probably not looking hard enough. The actual reason that it doesn't work is described in the article. And that reason is different than the reason the overbalanced wheel doesn't work, or the waterwheel example. All of these fail for different reasons, and simply saying "2nd law" is far, far more confusing than pointing out the actual reasons.
If you think the wording is unclear, or too wordy (guilty!) then by all means fix it. But the current lede is a shitstorm of far more confusing terminology. One issue pointed out above is introducing things the reader hasn't seen before, but the current version has a whole section about superconductivity that adds nothing but confusion and apparently is an attempt to demonstrate a counterexample and then explain it away. Come on.
Chetvorno has some excellent suggestions at the end there. So here goes...

Perpetual motion is motion that continues indefinitely without any external source of energy.[1] The term is most commonly used to refer to a perpetual motion machine, a device that continues to operate with no external inputs while producing useful work.

Proposals for perpetual motion machines have been made for centuries, although they all failed in practice. Early examples generally used basic mechanical systems to produce closed loop motion, using falling water to power a water pump for instance. Later examples tended to be based on any new scientific discovery; magnets, electrical systems and various materials effects have all been proposed. Before the mathematical understanding of the concepts of work and energy had been developed, there was no obvious reason why these devices would not work, and the failure of one design was not taken as an indication that another would not work. The development of modern physics, especially the concept of energy and the science of thermodynamics, has demonstrated that any such device is physically impossible.

Many perpetual motion machines fail because the design inherently requires more energy to run than the system contains, and once the initial store is used up the output will end. Such devices are said to fail the first law of thermodynamics, a specific case of the law of conservation of energy. Other designs are based on the conversion of energy from one form to another, or the use of different energy levels from which work can be extracted. The second law of thermodynamics demonstrates that all such process are inherently lossy, and these systems will leak away energy and eventually stop.[2][3][4]

Perpetual motion, in the strict sense of the term, is theoretically possible. The galaxies in the universe will move forever, by any practical definition, but no work is being extracted so they are not machines. Likewise, there are any number of common examples of machines that run for long times; a hydropower dam produces electricity from a seemingly endless supply of water, but the water is being provided by an enormous evaporation process powered by the Sun. It is important to contrast these examples with the concept of a perpetual motion machine in the sense that it is used here.

Despite the fact that successful perpetual motion devices are impossible in terms of the laws of physics, the pursuit of perpetual motion remains popular. Modern examples often claim to comply with both laws of thermodynamics but access energy from obscure source. These are sometimes referred to as perpetual motion machines, although they also do not meet the criteria for the name.

References

  1. ^ "Dictionary - Definition of perpetual motion". Websters-online-dictionary.org. Retrieved 2012-11-27. 
  2. ^ Derry, Gregory N. What Science Is and How It Works. Princeton University Press. p. 167. ISBN 1400823110. 
  3. ^ Roy, Bimalendu Narayan (2002). Fundamentals of Classical and Statistical Thermodynamics. John Wiley & Sons. p. 58. ISBN 0470843136. 
  4. ^ "Definition of perpetual motion". Oxforddictionaries.com. 2012-11-22. Retrieved 2012-11-27. 
The Websters-online-dictionary.org link is busted. That site itself now identifies as totodefinition.com, and does not have an entry for the phrase "perpetual motion". If we're looking for lay-language definition (or meta-search of several other lay-reader sites), maybe [1]? DMacks (talk) 04:48, 19 October 2014 (UTC)
Metric expansion of space is a different thing than objects themselves simply/actually physically moving apart. Dark energy describes itself as some sort of field or type of energy that causes the acceleration; therefore there is energy input involved, which contradicts the definition. I don't know enough about this topic to figure out what would happen (or if it's knowable, or even reasonable to ask) to the motion if the effect of dark energy were removed ("would it be perpetual even without it?"). DMacks (talk) 04:48, 19 October 2014 (UTC)
And astronomers differ about what will happen at the end of the Universe. A major possibility is the heat death of the universe, in which everything "runs down". Rather than debate cosmology, the introduction should make the point that all these systems are losing energy to friction or other losses, so they cannot continue moving "perpetually". --ChetvornoTALK 13:07, 19 October 2014 (UTC)
Which is a useless definition of perpetual in this context, and I admonish myself for saying anything because I knew it would turn into this sort of definitional BS. Maury Markowitz
  • "...but no work is being extracted so they are not machines."
This is characteristic of all perpetual motion machines of the 3rd kind, they serve as energy-storage devices, yet most are still called "machines". You would not call a gyroscope or a superconductive magnet a "machine"? --ChetvornoTALK 13:07, 19 October 2014 (UTC)
Sure you would, if they perform work. What do you think the definition of a machine is? Maury Markowitz
Both gyroscopes and superconductive magnets have been used to store energy and when the energy is extracted they do work, but by your definition if they are not producing work they would not be called "machines". I don't see that thermodynamics makes this distinction between "perpetual motion" and a "perpetual motion machine". Any system which has the potential to produce work indefinitely (or in the case of machines of the 3rd kind, store energy indefinitely) could be a "perpetual motion machine". --ChetvornoTALK 14:13, 19 October 2014 (UTC)
  • "Perpetual motion, in the strict sense of the term, is theoretically possible."
Unless you can find enough WP:RSs to refute the many sources that say perpetual motion is impossible, this can't be included. --ChetvornoTALK 13:07, 19 October 2014 (UTC)
Newton's First Law of Motion: "An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force." Every counterexample being offered here is a practical counterexample, hand waving at its worst... "well, eventually it will hit something". However, that lies outside the definition in the article as that is clearly an external source, and has no basis in the underlying physics. This is why it is vital that the idea of perpetual motion, and the concept of a perpetual motion machine should be clearly separated. Maury Markowitz
But you can't find a system in physics which is not acted on by an outside force. The above statement would require WP:RSs that "perpetual motion" is different from a "perpetual motion machine", and that perpetual motion is possible. I don't see significant support in physics for this view. --ChetvornoTALK 14:40, 19 October 2014 (UTC)
  • "The Browning Ratchet doesn't work because of the 2nd law, that simply tells you that you're probably not looking hard enough."
No, that's the wonderful thing about the thermodynamics laws. You don't have to look further. No machine, regardless of construction, can produce work from a system at equilibrium. That's what we're trying to get across to readers. The reason they fail is not due to their individual construction, but to general laws. The text does make this point but it needs to be clearer. --ChetvornoTALK 13:07, 19 October 2014 (UTC)
The article goes on to explain a twelve year hunt for the actual mechanism. Why do you think they bothered then?Maury Markowitz (talk) 12:33, 19 October 2014 (UTC)
From the article: "Any proposed perpetual motion design offers a potentially instructive challenge to physicists: one is certain that it cannot work, so one must explain how it fails to work. ...during that twelve-year period scientists did not believe that the machine was possible. They were merely unaware of the exact mechanism by which it would inevitably fail." --ChetvornoTALK 14:40, 19 October 2014 (UTC)
  • "a perpetual motion machine, a device that continues to operate with no external inputs while producing useful work."
Again, this is sloppy. It is a machine that continues to produce work without any external energy input. --ChetvornoTALK 13:07, 19 October 2014 (UTC)
Fine, energy. Maury Markowitz
The first law of thermodynamics is the law of conservation of energy. --ChetvornoTALK 13:07, 19 October 2014 (UTC)
No its not, or we would call it that. It is a specific sub-case of conservation of energy expressed in thermodynamics terms. Navel oranges are a type of orange, they are not equivalent to oranges. Maury Markowitz
My feeling is that this could be a good introduction, but the errors and misleading statements have to be corrected. It needs to be clear for the non-technically-educated readers. --ChetvornoTALK 13:07, 19 October 2014 (UTC)
What, like a completely unsupported statement about apparent perpetual motion in superconductors, which then tries to explain it away but utterly fails to do so? Maury Markowitz
I agree the present introduction is lousy.--ChetvornoTALK 14:13, 19 October 2014 (UTC)
The most important thing is that it has to state in no uncertain terms that perpetual motion is impossible, due to the two thermodynamics laws. --ChetvornoTALK 06:26, 19 October 2014 (UTC)
No, the most important thing is to state in no uncertain terms that perpetual motion 'machines are impossible, due to the two thermodynamics laws. These laws say nothing whatsoever about motion. Maury Markowitz (talk) 12:33, 19 October 2014 (UTC)
I personally don't think the lede needs all of these descriptions of "this isn't p.m. because x, that isn't p.m. because y". If you want a quick fix, it could be vastly improved by simply truncating it after "... (as occurs in energy harvesting)."
But for a better fix: the lede is supposed to summarize the article. The content and sequence of the lede, after the opening sentence, should be at least closely guided by that of the article body. Go through the article and start with one sentence per level two and level three section, then augment as necessary. If that doesn't produce a good lede, then the problem is not with the lede, it's with the article. Jeh (talk) 10:07, 19 October 2014 (UTC)
Whoa, logic to the rescue! Maury Markowitz (talk) 12:33, 19 October 2014 (UTC)
Yes, that could work. But I don't see a distinction in the article between "perpetual motion" and "perpetual motion machines", or anywhere that it says perpetual motion is possible. --ChetvornoTALK 14:13, 19 October 2014 (UTC)

Magnets[edit]

I have previously attempted to show that the reason the article gives for why the magnetic perpetual motion machine wouldn't work is incorrect. (See Talk:Perpetual motion/Archive 3#Ramp-and-magnet perpetual motion.) It didn't really get anywhere, so let's try again:

The seemingly mysterious ability of magnets to influence motion at a distance without any apparent energy source has long appealed to inventors. One of the earliest examples of a magnetic motor was proposed by Wilkins and has been widely copied since: it consists of a ramp with a magnet at the top, which pulled a metal ball up the ramp. Near the magnet was a small hole that was supposed to allow the ball to drop under the ramp and return to the bottom, where a flap allowed it to return to the top again. The device simply could not work: any magnet strong enough to pull the ball up the ramp would necessarily be too powerful to allow it to drop through the hole. Faced with this problem, more modern versions typically use a series of ramps and magnets, positioned so the ball is to be handed off from one magnet to another as it moves. The problem remains the same.

I believe that the highlighted sentence is inaccurate. (I see that it doesn't cite any references.)

Imagine a closed ramp, of whatever shape, and without magnets. If we put a ball at the top and give it an initial impulse, then - barring friction - it will return to the initial point. (Of course, you can't extract energy from such a machine; it just changes potential energy of the ball into kinetic energy, and vice versa. Gravity is not a source of energy.)

What happens if you add magnets to the ramp? Turns out, nothing much. Magnets are not a source of energy, either. The only difference they make is changing the value of the potential along the path of the ramp; there's still a point of the maximum potential where, if we place the ball and give it an initial impulse, it will theoretically make a full circle.

The argument the article gives is correct, to a point. If we place the ball anywhere and it starts spontaneously moving, it is by definition not at the point of maximum potential, and cannot make a full circle - for the same reason as if we place the ball at a slope (without magnets), it can't make a full circle, either: it doesn't have enough potential energy to reach the top of the ramp. (Of course, this assumes that the ball is initially at rest.) But it's NOT correct as stated, which can be easily shown.

Imagine a ramp shaped as in the schema below:

      M

     .|
    / |
   /  |
  /   |
 *    |
 \____/

If the ball weighs one kilogram, the force needed to pull it in vertically up is almost 10 Newtons. What prevents me from placing the magnet such that at point . it pulls the ball with the force of 9 Newtons? The force needed to pull a ball on an inclined plane is proportionally less, so if the ramp is diagonal, if I place the ball near the point ., it will roll up, then fall down the hole. It is true that the magnetic force decreases with the distance - but if the ramp is nearly horizontal at the starting point *, the force needed to pull the ball along it can be made arbitrarily small, barring friction. (Also, I could use a very strong magnet and place it far away from the device, reducing the gradient.)

We can see that under idealized conditions and given a carefully constructed ramp, if we place the ball at point *, it will roll up and then fall down; so the reason the article gives is incorrect. It still won't be able to complete a full circle; the point of maximum potential is not *. (I believe that such a ramp would have minimum potential somewhere near the start of the right bend of the bottom ramp, and maximum potential somewhere on its left bend close to point *.) But this is still a technicality: if we give the ball a sufficient initial speed, or start at the true point of maximum potential and give it an arbitrarily small initial impulse, it WILL make a complete circle. (No matter how unintuitive it seems, we could also push the ball to the right, and it would cycle in the opposite direction.)

So why the machine wouldn't work? As demonstrated above, it's not because "any magnet strong enough to pull the ball up the ramp would necessarily be too powerful to allow it to drop through the hole". Rather, it's for two reasons:

  • Friction and other dissipative forces would soon stop the machine; and
  • Even without friction, the machine could not do any work due to the law of conservation of energy; it would just change potential energy into kinetic energy and vice versa. Neither magnets nor gravity is a source of energy.

Mike Rosoft (talk) 06:38, 24 May 2015 (UTC)

The integral of the magnetic force on any object over any closed path, in any magnetic field, is zero. That's really all that needs to be said. Jeh (talk) 06:47, 24 May 2015 (UTC)
That's essentially the law of conservation of energy, correct? (As I have said, a magnetic field is not a source of energy.) - Mike Rosoft (talk) 15:30, 24 May 2015 (UTC)
Yes, it is because the magnetic field is a conservative field; it conserves energy. The above is the definition of a conservative field. The other fundamental fields of physics, the electric field and the gravitational field, are also conservative fields; any machine that works on any combination of these fields cannot be a perpetual motion machine. You can see that any machine that works in a cyclic motion cannot gain any energy from the field, because each of its parts, when it returns to its original position after a cycle will have the same amount of energy as before.
In your magnet example above, the total potential energy of the ball is the sum of its magnetic potential energy and gravitational potential energy. You could draw lines of constant total potential energy on your drawing above, similar to contour lines on a map. There will be a minimum (a potential "well") at the magnet pole, and another along the ground level. Between the two there will be a curving "ridge" or "saddle" line of maximum potential energy. If the ball is started in a stationary state, whichever side of the ridge it is started on it must stay on that side; it does not have the energy to cross it. If it is started above the line on the magnet side it will end up at the magnet pole, while if it is started below the line it will end up at ground level directly under the magnet. --ChetvornoTALK 19:13, 24 May 2015 (UTC)
Mike Rosoft is right, and while the comments from Jeh and Chetvorno also contain correct statements about the physics, neither of them answers Mike's essential point. A magnet which was strong enough to pull the ball up the ramp would, in an ideal situation without friction, air resistance etc, give the ball enough kinetic energy for the ball to go flying past the magnet, and, if there was no floor underneath, the ball would then drop down under gravity. Of course the device wouldn't work, but for the usual reasons why perpetual motions don't work, namely losses due to friction etc, not due to the magnet's not letting the ball drop. I shall edit the article to remove the erroneous statement. The editor who uses the pseudonym "JamesBWatson" (talk) 13:39, 29 May 2015 (UTC)
Hmm. When I wrote the above message, I intended to replace the incorrect statement with a better one, but when I tried to think out a better one, I could not think of a suitable concise statement of what the true problem is, so I have just removed the wrong explanation, leaving "The device simply could not work" without any explanation. Not at all satisfactory: can anyone do better? The editor who uses the pseudonym "JamesBWatson" (talk) 13:48, 29 May 2015 (UTC)
There are many possible trajectories but they all end with the ball stationary at one of the two potential energy minima in the problem; either at the magnet's pole or on the bottom ramp directly under the magnet. --ChetvornoTALK 21:27, 29 May 2015 (UTC)

Perpetual motion[edit]

Perpetual motion is not Impossible but inevitable. I give you to you perpetual motion. Its far to easy to explain and I guess only a abstract mind would find it. The age old idea of turning a water wheel with a Archimedes screw. Works! if you float the entire thing underwater. And give it mercury run on. Chuxgold. — Preceding unsigned comment added by 172.78.220.253 (talk) 05:07, 25 September 2015 (UTC)

No it doesn't, but that's beside the point. This is not a place for abstract discussions of perpetual motion, but rather a place to discuss improvements to the article KaturianKaturian 18:56, 27 September 2015 (UTC)
Putting the whole setup underwater would only create more friction. Water is a more viscous fluid than air. Your machine will stop moving even sooner.202.73.1.98 (talk) 09:54, 17 November 2015 (UTC)

even enduring physical objects are ultimately transient[edit]

I have altered parts of the lead. A dictionary is not an adequate source for this kind of definition, because a dictionary reflects the wide usage of words, including unencyclopedic usages.

Atoms continue to move even when they are elements of an isolated system. What does not continue is not their motion, but, rather, is the forms and motions of enduring physical objects that they constitute.

The idea of "the heat death of the universe" is an obsolete nineteenth century speculation that goes far beyond present scientific knowledge. The long-term future of the universe is not known to present-day science, and is not strictly relevant to the concept of perpetual motion. A Wikipedia article is not in general a reliable source.Chjoaygame (talk) 22:54, 7 December 2015 (UTC)

Blackbird 'see also' edit[edit]

I have undone an edit that added a 'see also' link to a land sailing vehicle. The story of the vehicle sounds remarkable and interesting, but it is not a perpetual motion machine. Perhaps it may lead to something that might intend to be a perpetual motion machine, and that would make it relevant to this page. But at present it hasn't got to that point. Perhaps others may think I am wrong to have undone this edit, and they will undo my undo. Let's see.Chjoaygame (talk) 10:56, 12 January 2016 (UTC)

I support the reversion. Sailing upwind has nothing to do with perpetual motion. --ChetvornoTALK 12:22, 12 January 2016 (UTC)
  • Support this isn't an article about counterintuition, though perpetual motion does fall under that category, too. Rklawton (talk) 15:38, 12 January 2016 (UTC)
(Just for fun. For it to make sense that the speed of the Blackbird exceeds the wind speed, one needs to include the ground (or some other thing) as a reference. The windmill blades must collect energy from the wind and this energy must be made to move the vehicle relative to the ground. The vehicle's wheels must exert traction on the ground. On this argument, the Blackbird seems possible if the windmill blades are adequate.Chjoaygame (talk) 16:17, 12 January 2016 (UTC))
It's powered by wind, which is just sun power once removed. Sailing upwind, whether in a boat or in a wheeled vehicle, whether by tacking with conventional sails or by tying a boat's propeller or cart's drive wheels to a windmill, is no great trick. And for such a windmill-powered cart to "exceed the wind speed" could be just a matter of gearing, assuming that the windmill fan blades are big enough. It has nothing to do with perpetual motion. CoE does not say anything about velocity; as long as the energy extracted from the wind is greater than the k.e. added to the cart, plus losses, you're on the right side of the laws of t.d. Conservation of energy and the laws of thermodynamics (loosely: You can't win; you can't break even; you can't even quit the game) do not prohibit the cart's motion from having greater velocity than the wind. They only require that the k.e. energy of the cart, plus the inevitable losses, can't be greater than what you extract from the wind. Jeh (talk) 04:21, 19 January 2016 (UTC) (Edited per Ch.'s comment below.) Jeh (talk) 11:01, 19 January 2016 (UTC)
For people like me, CoE means conservation of energy. But you need also to comply with the second law to be on the right side of the laws of thermodynamics.Chjoaygame (talk) 07:20, 19 January 2016 (UTC)
I agree. I was going for clever wording and ended up with the wrong wording. Edited. Jeh (talk) 11:01, 19 January 2016 (UTC)
How I imagine it working is an electric car that has a turbine, behind the grill, that catches the wind and converts it to electricity with an electric generator. There would be side vents and a bottom vent for max air flow. The car would need to generate just over 20Kilowatts for it to be "Perpetual". I've pitched it a few times over the years to Apple Inc. Kcida10 Kcida10 (talk) (Uploads) 11:43, 30 January 2016
I think that is far more complicated than necessary, even missing the point entirely. All you need is very good gears (no friction) and a big and efficient windmill.Chjoaygame (talk) 06:38, 31 January 2016 (UTC)