Why We Don’t Discuss Perpetual Motion Machines (PMM)

[russ_watters]

Authorship Contributions From Anorlunda
You may want to believe the article you read, or the video you saw, or you may be very proud of your PMM invention.   It can be very difficult to analyze what is inside the box to find the flaw. Maybe we can’t find it. Maybe nobody can find it.  If we can’t find the flaw, does that mean it will work? No, it does not. If you want to understand why read this article.
The PF guidelines explicitly list Perpetual Motion and Free Energy as forbidden topics.  Why? They are certainly popular topics. Almost every day we get new posts about articles that people read elsewhere, or from creative inventors.
The short answer is that a PMM would violate either conservation of energy, the 2nd law of thermodynamics, or both.   To a scientist or engineer, that is enough. Case closed, thread closed. But that may sound insufficient, dismissive, or even rude to the posters.  So a longer...

Continue reading...

 

[hutchphd]

Very nice article.
Having been occasionally engaged by two patent attorney friends to provide guidance to would-be inventors, the advice for the "iconoclastic" PMM purveyor to try to design/build a working prototype was absolutely the best method to rationalize their enthusiasm. Surprisingly often it was the only way to keep them from squandering a boatload.

 

[Bandersnatch]

Thanks for this. I was just thinking how we could use a more thorough explanation for this particular forum policy, since the Guidelines are rather skimpy in this respect.

It's comprehensive, to the point, and not condescending.

Now, if we could have this as a link in the Guidelines instead of (or in addition to) the wikipedia and skepdic links...

 

[anorlunda]

Now, if we could have this as a link in the Guidelines instead of (or in addition to) the wikipedia and skepdic links...

Good suggestion. I just edited the copy of the guidelines here:
https://www.physicsforums.com/threads/physics-forums-global-guidelines.414380/

But there is a second copy of the guidelines that we need @Greg Bernhardt 's help to edit here:
https://www.physicsforums.com/help/terms-of-service/

 

[Klystron]

Excellent essay. Asking for a prototype also helps distinguish between inventors and outright scoundrels.

I remember a quasi-religious cult figure asking members to send gold objects to cult headquarters in order to substantiate a "Golden Pyramid". Since pyramids are "proven" energy sources, imagine the energy once the master coats the pyramid with gold. When asked to measure this energy increase, the master sorrowfully relates that the skeptic's negative energy flow creates interference. How much gold actually makes it to the pyramid requires a different measurement.

 

[bhobba]

First nice article. Great you mentioned Noether's Theorem which for me really says it all.

Thanks
Bill

 

[atyy]

But aren't we now discussing PMMs

 

[Ibix]

Asking for a prototype also helps distinguish between inventors and outright scoundrels.

Worth noting that a man called Joseph Papp built a "perpetual motion machine". Feynman was invited to see it and, knowing that it was a scam, disrupted the demo. The device exploded, killing one observer (see Feynman's write up, and some discussion supporting its authenticity). It's unlikely to happen with the genuine (if that's the right word) inventors because their devices just won't work, but scammers need their devices to "work" so they must contain some energy storage mechanism.

 

[anorlunda]

see Feynman's write up,

Interesting, and typical Feynman style. I'm fond of James Randi and his debunking methods. But as far as I know, Randi never turned his attention to PMMs.

 

[berkeman]

But aren't we now discussing PMMs

Yes, and everybody posting in this thread will be receiving an infraction, as soon as I get my PMM prototype working. Oh wait...

 

[Ibix]

I'm fond of James Randi and his debunking methods. But as far as I know, Randi never turned his attention to PMMs.

I suspect it's rather a different skill set. While I rather suspect the psychology is similar (genuine believers, puzzle designers, and scammers exist in both areas), there's quite a lot of scientific knowledge needed to explain in detail where the flaw in a PMM design is. And even more to explain it in an engaging way - debunking PMMs is essentially the thrilling art of book-keeping, after all.

 

[anorlunda]

there's quite a lot of scientific knowledge needed to explain in detail where the flaw in a PMM design is.

The article discusses exactly that. But the Feynman anecdote describes an entirely different approach to derail a demo of a fraudulent live prototype. Randi was skilled at figuring out how con men think, and from that how to derail their cons.

Actually, maybe in the article we should have distinguished between deliberate fraud, and innocent but naive "inventors."

 

[berkeman]

We get PMM posts in many guises here at the PF all the time. Great reply by @jrmichler in this current thread, for example...

Any piston that compresses isothermally must do so at low speed. A practical reality of low speed operation is that mechanical friction losses and leakage losses become a larger percentage of the total work. There is a speed that minimizes both adiabatic losses and mechanical friction losses, for the best compression efficiency. At that speed, the compression cylinder is "large", thus expensive. The most economical compression design trades off adiabatic losses, friction losses, capital cost, and operating cost to get minimum net present operating cost.

For an example of the reverse situation, search Atkinson cycle engine. The Wikipedia hit is a good place to start.

Then study some thermodynamics until you understand that you are trying to invent, if not a perpetual motion machine, a cycle better than the Carnot cycle (search that term also).

Do all of that until you can discuss your cycle using the correct equations, and calculating the efficiency relative to both isothermal and adiabatic compression. Do this while recognizing that your design cannot do perfect isothermal or adiabatic compression. Include pressure - temperature - time curves for your cycle, isothermal compression, and adiabatic compression. Discuss the conditions necessary to get isothermal and adiabatic compression, with calculations.

If you spend sufficient time studying the above, show us your work and we can help you proceed further.

 

[essenmein]

What about those self running 3 phase dual permanent magnet self running motors? They are legit right? Permanent magnets contain all the energies?

 

[anorlunda]

What about those self running 3 phase dual permanent magnet self running motors? They are legit right? Permanent magnets contain all the energies?

I'm not sure what you mean, but no. PM PMMs are not OK, no pun intended.

 

[essenmein]

Basically it was a joke about all those guys on youtube that are convinced permanent magnets contain magic, or somehow phase angle is connecting with the vacuum energy and that is why a 3 phase machine turning a DC motor with phase shift is apparently the secret to free energy. Mostly because magnets though I think.

 

[snorkack]

What about those self running 3 phase dual permanent magnet self running motors? They are legit right? Permanent magnets contain all the energies?

Not if the permanents magnet remain magnets. Magnets can store energy, but are not a very efficient energy storage.
To have a genuine workable perpetuum mobile of first kind, you need to address squarely the Noether theorem. Not its validity, of course, but the symmetries that require conservation of energy.

Which asymmetries are needed to run a perpetuum mobile? If those asymmetries exist, can you observe them without actually using them to change energy?
And nonconservation of energy is by no means a sufficient requirement for a perpetuum mobile of first kind. Obviously a device capable of destroying but not creating energy is not a perpetuum mobile of first kind.

 

[hutchphd]

Having been occasionally engaged by two patent attorney friends...

Most of the time these were well-intentioned folks who were true believers. I felt like the damned Grinch as I tried to bring them down easy.

 

[member 656954]

there's quite a lot of scientific knowledge needed to explain in detail where the flaw in a PMM design is

This is my failing with a persistent poster on another social site. I actually asked for hints on PF regarding his supposed internal combustion engine tech that runs on any fuel, at full torque, with no emissions...looks like magic, to me...but the thread was locked under the PMM rules

(I'm not disagreeing with the rule, BTW, and can see the rabbit holes it would take you down, because if this guy is typical, they don't engage, they just moan about how wonderful their idea is and how it's being "suppressed" by <some big company/industry>, and explain that they can't give you any details due to patent pending, or some such. We all have blinkers, but the self-deception required to genuinely believe you've invented a PMM seems a black hole of hubris.)

 

[Rive]

What about those self running 3 phase dual permanent magnet self running motors? They are legit right? Permanent magnets contain all the energies?

It is difficult to make a good PMM joke what keeps on running and won't get shot down

 

[HallsofIvy]

But it's alright to post questions about pink unicorns, isn't it?

 

[Dadface]

It was Professor Sir George Porter who said that when he became a bit of science populariser he got lots of communications from people sending him their designs for PPMs. In the early days, he replied to them all pointing out why their machines wouldn't work but he had to give up doing this because it became too big of an imposition on his time.

 

[russ_watters]

But it's alright to post questions about pink unicorns, isn't it?

Yes, as long as they aren't invisible.

 

[russ_watters]

It was Professor Sir George Porter who said that when he became a bit of science populariser he got lots of communications from people sending him their designs for PPMs. In the early days, he replied to them all pointing out why their machines wouldn't work but he had to give up doing this because it became too big of an imposition on his time.

We had the same issue and resolution in the early days of PF.

 

[chemisttree]

Oh man! All my time has been wasted working on this Jupiter Toy Company Casimir Generator Turbine I guess...

Oh nevermind! Its been patented!

 

[arivero]

The Engineer’s Tool, The Black Box An engineer would analyze a PMM idea as follows. Imagine the PMM to be enclosed in a black box. We can’t see inside, so we can’t see what the PMM is or what it does. Carnot Heat Engine diagram Energy conservation tells us that Energy In=Energy Out + Losses. Statistical arguments similar to thermodynamics tell us that Losses are greater than zero for macro objects. That is true no matter what it in the box. What is in the box doesn’t matter. PMM thread posters always want us to examine the details of what is inside the box (i.e. the PMM) to find a logical flaw. The engineer says, “Nope. What is in the box doesn’t matter.” That’s not being rude, it is being confident of our analysis methods and the laws of physics.Except that in most popular cases the important details are the impedance of the black box. In some minor case, it is the capacitance. But here is what happens in modern PPM: people measure input with a Voltmeter, and Amperimeter, and just multiply because power = V A. But the current is A/C, and the device has impedances. So the inventor does a failed Black Box Analysis.

 

[linkhyrule5]

I'm actually not terribly impressed with this article. It doesn't actually seem written to convince or would-be "inventors" of the flaws in the concept, just to earn free likes from people who already agree. Just saying "conservation of energy has been thoroughly tested by observation" isn't really that much different from saying "conservation of energy is a fact, thread over." (Besides which, what about the expansion of the universe?)

A better version would take the time to really explain why conservation of energy is such a keystone of our theories -- actually explain Noether's theorem and how conservation of momentum arises from spatial symmetries, perhaps, before then going on to explain how CoE then follows from time symmetries, for example; or go into detail about exactly how and exactly how thoroughly we've tested the concept, referencing things like the very thin line-widths of emission spectra and so on.

As it is, it feels more like an applause light than an actual attempt at educating people.

 

[berkeman]

I'm actually not terribly impressed with this article. It doesn't actually seem written to convince or would-be "inventors" of the flaws in the concept, just to earn free likes from people who already agree. Just saying "conservation of energy has been thoroughly tested by observation" isn't really that much different from saying "conservation of energy is a fact, thread over." (Besides which, what about the expansion of the universe?)

A better version would take the time to really explain why conservation of energy is such a keystone of our theories -- actually explain Noether's theorem and how conservation of momentum arises from spatial symmetries, perhaps, before then going on to explain how CoE then follows from time symmetries, for example; or go into detail about exactly how and exactly how thoroughly we've tested the concept, referencing things like the very thin line-widths of emission spectra and so on.

As it is, it feels more like an applause light than an actual attempt at educating people.

Welcome to the PF.

Hopefully the links to further reading provide what you are looking for. Insights articles are meant to be informative and of a practical length -- not a full textbook.

If you're interested in writing a more in-depth Insights article as a "Part 2" to this one, please feel free to do that and submit it to one of the Mentors for review. We always appreciate quality help here.

(BTW -- one of the big motivations for this particular Insights article was the large number of such PMM thread starts that we get here. We close them quickly with links to more reading, but it was felt that an Insights article would be a better thing to post during the closing of those threads to help the OPs.)

 

[member 656954]

A better version would take the time to really explain why conservation of energy is such a keystone of our theories -- actually explain Noether's theorem and how conservation of momentum arises from spatial symmetries, perhaps, before then going on to explain how CoE then follows from time symmetries, for example; or go into detail about exactly how and exactly how thoroughly we've tested the concept, referencing things like the very thin line-widths of emission spectra and so on.

The depth of an Insight article is an interesting challenge.

Having spoken to a number of 'over unity' zealots, I seriously doubt they would care about all this, or want to take time to understand any of it. To continue to believe you've created a PPM in the face of what will be a lot of well-founded skepticism takes a certain frame of mind, and finding reasons to doubt you've done it is the exact opposite of what seems to be a "You're just trying to hold be back" response.

Which leaves interested PF members as readers, and those will follow up the noted details if interested, but I contend they're already 'converted' to the understanding that PPMs are Impossible, so don't need it all laid out in one Insights article to the degree you might prefer. Indeed, that level of detail may put off the lay reader, who gives up because it's all too hard.

 

[DrClaude]

This is my failing with a persistent poster on another social site. I actually asked for hints on PF regarding his supposed internal combustion engine tech that runs on any fuel, at full torque, with no emissions...looks like magic, to me...but the thread was locked under the PMM rules

It is very difficult to moderate threads on such topics, even if the angle taken is the scientific one. This is why we usually don't allow debunking threads, unfortunately.

However, some threads are accepted (it is always a judgement call on the part of the mentors). You can be successful by restricting the question to a specific aspect.

(I'm not disagreeing with the rule, BTW, and can see the rabbit holes it would take you down, because if this guy is typical, they don't engage, they just moan about how wonderful their idea is and how it's being "suppressed" by <some big company/industry>, and explain that they can't give you any details due to patent pending, or some such. We all have blinkers, but the self-deception required to genuinely believe you've invented a PMM seems a black hole of hubris.)

People with that mindset will never listen to reason.

 

[arivero]

A better version would take the time to really explain why conservation of energy is such a keystone of our theories

If you're interested in writing a more in-depth Insights article as a "Part 2" to this one,

Having spoken to a number of 'over unity' zealots, I seriously doubt they would care about all this, or want to take time to understand any of it.

Problem is that some of them really measure over unity, and they just conjecture that they are extracting energy from somewhere. They do not doubt energy conservation, they just thing they have found a new source.

Explanation should address why they are measuring wrong. Most cases, as I said above, is not understanding AC (and surely they will claim to be followers of Tesla ) Some others is pre-storage of energy, either in mechanical or chemical form. Remember all the "water engines" actually burning aluminium. Some other are more subtle, when the "overunity" is one hundred of the circulating energy, then analysis is a lost cause: it can be thermal expansion, gravity doing its job, whatever.

 

[berkeman]

Aaand since we are starting to veer into debunking replies, it's probably a good time to tie this thread off.

Good Insights article -- I'm sure its link will get used a lot in the future here in the PF as we lock PMM threads by newbies.

Thanks everyone for a good discussion of the Insights article.