exchemist

1 minute ago, Prajna said:

I did add a rather conspicuous wink but thanks for the clarification.

OK.

36 minutes ago, sethoflagos said:

You're not answering the question I asked.

When there is a tab directly between the magnets, are the magnets at minimum separation, maximum separation, or somewhere in between.

Just to be absolutely clear on where you want to push and when you want to pull. It makes a difference. Rather like the ignition timing on a combustion engine.

As I understand it, the idea is inserting the tab, or finger, causes the magnets to be attracted to it, instead of repelled from one another as they are in the previous phase of the motion. 

If we describe the operation in terms of an engine cycle, there are 4 phases:-

1) magnets close together no tab inserted, high energy of the field

2) magnets have moved apart due to mutual repulsion, reduction in field energy. Work imparted to output shaft

3) tab or finger inserted into the gap, causing magnets to be now attracted towards it, with further lowering of field energy. More work output to the output shaft (and some work output to the input shaft as well, due to the attraction)

4) tab removed from the gap between the magnets, which are now close together. This replaces the force of attraction to the tab or finger by mutual repulsion of the magnets, which are now at close separation, i.e. back to (1). It is this step that requires the substantial work input which returns the stored energy in the field to its stating value. Failure to realise the work need to do this is what can lead the incautious designer to think he has an over-unity machine, as the other steps all involve extracting work from the magnetic field.

At least, that is my energy-based analysis of this machine. 

1 hour ago, Prajna said:

In the current design the tabs or fingers are arranged every 20 degrees around the rotor. There are nine tabs and the rotor axle is co-planar with the centre line of the magnets, so when there is a tab central to the gap between the magnets on one side there is a space on the opposite side. The magnets are 10mm x 2mm neodymium (N52?) and the tabs centres are at approximately a 35mm radius. The 'bulb' on the tabs that lies between the magnets is 5mm radius to match the area of the magnets. This may be more or less optimal as far as effectiveness in switching the flux and suffering eddy current drag, I don't know yet.

This is somewhat arbitrary and is just my first best guess of what might work.

I wish you guys would stop with the perpetual motion slur, I'm rather hoping for over unity!

Over unity is the same thing as what is traditionally known as a “perpetual motion machine of the first kind”, i.e. one that claims to break the 1st law of thermodynamics.  So it’s not a slur. 

There have also been ideas for perpetual motion machines of the 2nd kind, which claim to break the 2nd law of TD instead.

As I have mentioned, it can be good sport to spot the flaw in the logic of the designer. 
 

A rule of some patent offices, e.g. the US one, is patent applications for perpetual motion machines will only be accepted if accompanied by a working model. Which they never are, of course. So recognising perpetual motion machines is something patent office examiners (as Einstein once was,incidentally) and patent agents have to be able to do.

28 minutes ago, Prajna said:

Sorry, I don't understand. Unless you mean it's a win that I'm belatedly reading about magnetism and you don't need to be involved in analysing the device.

By the way, I stumbled back on the article about monopoles, for anyone interested, it was in Popular Mechanics: https://www.popularmechanics.com/science/a60079037/magnetic-monopole-hematite/

Both: we’ve solved the conundrum presented by your machine, I’ve revised some magnetism I haven’t looked at since school, and you’ve become motivated to learn more about it. And for me, another perpetual motion machine bites the dust, which I can add to my tally. 

6 minutes ago, sethoflagos said:

Different words, same thing. It's the repulsion of like poles that causes the field rotation I took as a given for sake of brevity.

Oh I see. 

20 minutes ago, Prajna said:

It's not so unusual though for magnetic fields to be sharply bent, a keeper on a horseshoe magnet does this when placed across the poles, providing the shortest possible low reluctance path for the field and containing it, effectively neutralising the magnet.

By the way, I've just taken a look at the Ferromagnetism page on Wikipedia and am finding it very helpful in understanding magnetism. Soon I may be able to drop my naive model and speak intelligently about it.

Well that's a win, then! 

It's been an interesting discussion. 

57 minutes ago, sethoflagos said:

Perhaps one way of looking at this contraption is to compare it with a Faraday disk (aka homopolar generator).

In the latter, both motion and induced current are in the plane of the disk with the magnetic field perpendicular. The OP is rotating this so that motion and magnetic field lines are in the disk plane therefore forcing induced current into the perpendicular. However, different portions of the disk will see different current polarities depending on whether they are moving towards or away from the magnetic poles. In particular, the portion of the disk passing directly between the poles will see a sharp switch in polarity and consequent current flow component appearing in the disk plane. This will in turn deflect the magnetic field lines somewhat out of the disk plane as if attracted by a temporary opposite pole.

I don't know whether it's a good picture, but in my mind's eye, I'm seeing this induced temporary pole falling into a potential well only to climb back out as it departs with no nett overall energy change in and of itself. However these circulating currents are a different matter as they will add a time lag to the ideal case making ascent harder than descent, acting as a brake in exchange for simply heating up the disk.

 

One important difference, though, is that in the OP's machine the poles of the two magnets are opposed so that they repel. The region in which the fingers on the input disc move is in principle an area in which the field lines will be squashed outwards in the plane of the fingers of the disc. 

1 hour ago, Prajna said:

This is exactly the conversation I hoped to have here, @exchemist. Yes, my preliminary experiments showed that with magnets in repulsion a steel sheet, in this case a steel rule, inserted into the gap caused the magnets to be attracted to the rule. My guess at what is happening there is (if you'll indulge my less-than-physically-exact language) the magnets in repulsion, because their competing fields offer a very high reluctance to the other's flux path, try to complete their circuit by adopting (and attracting) the steel rule, a much lower reluctance path, into their circuit. When the rule is removed the magnets again face an unacceptable high reluctance to their circuit and therefore attempt to mitigate it by moving apart.

OK, in that case, what I think you will find is it takes significant effort to pull the finger out of the gap, as the force of attraction is stronger once the magnets have moved inward, than the force that pulls it into the gap when you insert it. So you do net work on the system that way and this provides the energy that restores the stored energy in the fields to the status quo ante. 

2 hours ago, Lahearle said:

If I combine a compound which contain a ratio of 3/8 hydrogen/oxygen and heat it to 2600 F, according to PV = nRT 

how much will the pressure increase when it reaches ignition temperature (1058 F), and how big do I need the container to avoid it exploding and spewing lava everywhere?

Yes I am noob so please talk stupid to me. 

The compound has only hydrogen, carbon, oxygen and nitrogen.

Won't the answer depend on what the products of decomposition are going to be, as well as on the enthalpy change, which may heat the mixture further ? Both of these will depend on what your undisclosed compound is.

Also, why do you speak of "lava"? Lava is molten rock and rocks do not ignite, as a rule.

12 hours ago, Prajna said:

Ok, the situation in the device though is that the magnets are not moved closer nor separated by the operator, rather the magnets move under the effect of their changing state of repulsion or attraction governed by whether there is a finger or no finger between them. So, in my view, energy is being exchanged between the magnetic fields on one side of the device and the fields on the other. Is this a reasonable description? The operator is not moving the magnets, not even by poking them with a stick, he is merely turning the rotor that determines which side of the device has a finger in the gap and which doesn't. Maybe I should rename my 'fingers' to 'tabs' to avoid the idea that there is any poking of the magnets going on.

I don't see where there is any direct link between the work or energy or effort required to turn the rotor and the work or energy or effort produced by the switch state of the magnets, unless there is some reason to suggest that the eddy current drag is directly related to the output. The drag will certainly depend on the strength of the magnetic field on the side of the device that the finger/tab is passing through and the speed of the finger/tab through that field and, I guess, on the area of the tab that's in the field, perhaps even other things I have yet to consider.

OK, now we get to it.

In your proposed machine, the magnets first repel one another, doing work and lowering the stored energy in their respective magnetic fields. You believe that when you insert the steel finger between them, they will then be attracted towards it, doing more work and further lowering the stored energy in their fields. And then, when you move the finger out of the way, they move apart again due to repulsion, extracting yet more energy from their magnetic fields.

This obviously cannot be the case.  So there is something wrong with your assumption. Either you will find the magnets are not attracted together when the steel finger is interposed, or you will find the finger resists being inserted or removed, such that the operator has to do work against the field, thus supplying the required energy. At the moment (being a chemist rather than a physicist) I am not sure which of the two it is, but logically it must be one or the other, it seems to me. My suspicion is that the magnets will not be attracted to the finger. If you consider the path of the flux lines when the finger is in between, they have to turn sharply horizontal within the finger and pass outward to each side. This I think means the dipoles within the finger will not be able to align themselves with either field in the way that you (implicitly) suppose, as they will be perpendicular to the fields,  and so no attractive force will result.

If that's right, you would be able to twiddle the finger wheel as fast you like and bugger-all will happen!  But perhaps you should build it to confirm exactly how it fails to work.    

On 4/17/2024 at 12:37 AM, JohnDBarrow said:

It is my notion that if all humans could have babies, not just half of the species, that would pretty much double our reproductive capacity. Men can fertilize women much faster than women can bear children. Women are only about half the population within the age group of human fertility. In unisex species, reproduction rate and baby-making efficiency are measured in the female, not male, half. 

Think about what our world numbers might be if our species was 90% women!

I think you are overlooking the time and effort it takes to nurture a human baby. Before modern human societies arose, you needed two parents to raise a child, because of the long time it takes before a young human is independent. 

4 hours ago, JohnDBarrow said:

What are the pros and cons of this reproductive set up?  I ask because my mother once remarked that this world would be a better place without male and female. 

She said this in response to my remark that male and female is a beautiful thing of nature. 

As times progress onward, the differences between male and female seem to becoming more and more confused. There are certain societal and political biases that seem to put one or the other sex at a disadvantage. Men are often given harsher sentences for the same types of crimes because judges view men as naturally more menacing than women perhaps because of the perceived muscular strength of men and that women are looked upon as naturally weaker and less competent. We still have a Girl Scouts for absolutely females only but there is no longer a male-only Boys Scouts. It seems as the male side of our species is especially becoming less relevant. 

 

The biological aspect of your question has already been addressed in your previous thread, hasn’t it?

The social observations you now make seem on the face of it a bit ridiculous. If you really think the way the scout movement is organised shows the male of our species is becoming irrelevant,  it looks as if you are getting things out of perspective. But I note the reference to your mother.  Are you a Boy Scout, or something? 

7 minutes ago, Maartenn100 said:

Think about it: the brain is nothing different than electricity flowing through wires. The brain is an electricity-producing machine. That's what we are. And electricity flowing through wires produces magnetism. And maybe, magnetism = consciousness.

This is stupid. A computer is not just wires. Only an idiot thinks that. Nor is a brain just a mass of biochemical wiring, either.

Try to apply a bit of sense, for goodness sake.        

27 minutes ago, Prajna said:

Chatham: yes, there was a nuclear submarine port there, I believe. Sailing on the Medway is very interesting too, that sub being one fascination.

Good, we're getting closer now. I think @swansont is still confused in thinking I'm talking about lifting something by attaching it to a magnet and lifting the magnet whereas I'm talking about the magnet being fixed and the object being lifted by the magnetic field. There's some ambiguity somewhere and I am not sure if it is in what I described or in @swansont's understanding of what I describe. No matter. I hope he can agree that in the thought experiment I described the magnet appears to be doing work as in W = fD. Certainly it looks like work is being done. Once we get this thought experiment done and dusted then maybe we can examine my proposed device and see how we correlate what is happening in it with thermodynamic laws. Maybe we can even discuss it in general terms without having to divert into obscure formulae.

Can we say then, in this thought experiment with a fixed magnet attracting to itself, that work is being done by the magnet? Can we say also that the strength of the magnet is not depleted in the process of that? In that example some work must be done to remove the steel sheet from the magnet, if it is a permanent magnet, or the current must be interrupted to let the sheet fall if it is an electromagnet. So we can include that work and so on and develop the experiment further to include the mechanics of removing the sheet again etc. but let's leave that there and move back to the SMT.

In the SMT the magnets are fixed at the end of rockers (levers really, on an axle at their centre). When a metal finger is rotated into the space between the magnets then the magnets will switch from repelling each other to being attracted to the finger. Obviously some work will be required in order to rotate the finger into the space. That work will be reduced, maybe even to some extent overtaken by the finger being attracted into the field in the gap between the magnets. Obviously the reverse will be true as the finger exits the gap since the field is still attracting the finger back into the gap and this will add to the work required to rotate the finger out of the gap. So these two effects should balance or cancel each other out. This is what I mean by 'symmetrical and why I disregard this effect since overall it neither adds to or reduces the force required to turn the rotor.

There will be some eddy current drag on the finger as it passes through the magnetic gap, since any ferromagnetic material passing though a magnetic field acquires an induced magnetic field opposite to the magnetic field inducing it. How much drag will that be? Probably it will be proportional  to the strength of the magnetic field that gives rise to it, that's logical and I'm happy yo accept that being the case.

The magnets, in attraction to the finger on one side of the rockers and repelling each other on the other side, will cause movement, work in fact, on the rockers, causing them to rotate in a reciprocating manner as each magnetic gap encounters either a finger or a space. The force involved in that movement will depend on the strength of the magnetic fields which will vary dependant on the distance the opposed magnets are from each other - when the magnets are close they will exert more force, either in attraction or repulsion, and the converse; according to the inverse square rule.

It may be that whatever the power of the magnets the eddy current drag will always be equal to the forces generated by the magnets in switching from attraction (to the finger) and repulsion (on the side that has a space rather than a finger.) Or maybe the eddy current can be reduced, perhaps by making the fingers small enough that they only just switch the magnets, perhaps by redesigning them to use some form of lamination such is done in transformers to reduce eddy currents.

I'm not sure if you have noticed but when a magnet is stuck to a sheet of metal the force required to remove it can be much reduced by sliding it transverse to its field. In the SMT the fingers pass transverse to the field rather than in line with it and, like sliding a magnet off a sheet of steel, there may be less work required than if something was moving in line with the field.

Thanks for further constructive comments, @exchemist

Did I say the area of the plate was greater than the magnet? You're again talking about attaching something to a magnet and then lifting the magnet. I'm not. I'm talking about a SMALL plate of metal being ATTRACTED to a magnet that is in a fixed position. Do your stress tensors and Hookes laws and elastic distortions really contribute to what I'm discussing? Thanks for your interest but I really don't think what you've offered is contributing to illuminating what I was discussing.

It's very simple. W=Fd is all you need to keep in mind. If there is no change in d, the distance in the direction of F, no work is done. Move them apart and you do work on them, causing energy to go into the magnetic field (a form of potential energy). Allow them to move closer and the reverse happens: they do work on whatever is holding them apart, with the necessary energy coming from the magnetic field.

As for the magnet sliding, that is a distraction. It does not in fact alter the strength of the magnetic force holding it to the metal sheet. Any motion perpendicular to the force means d does not change, so no work is done. 

(What it may do, though, is reduce the frictional force parallel to the sheet which resists the magnet being slid. Typically the frictional drag between two surface that are sliding past one another is less that the limiting friction just before the force is overcome and sliding commences. This is to do with asperities on the surface interlocking, which does not happen to the same degree when they are in motion. But this is a tribological digression.)

38 minutes ago, CharonY said:

I think there is a distinct difference how the public and how public health are seeing these events. Here is the thing, when mpox started to spread, it was kind of a best case scenario for public health intervention. It is moderately harmful, but not catastrophic, has visible symptoms, diagnostics exists and it requires direct contact to spread.

Especially with elevated public health control still ongoing and rapidly deployed monitoring efforts (including wastewater testing), the assumption was that it should have been easy to mount a rapid response. What actually happened is still being discussed. However, what clearly did not happen was an early containment, it ultimately spread across multiple countries and was declared a so-called public health emergency of international concern in 2022. The case numbers went down in 2023 and the emergency ended, and some consider that an success (around 100k infections in more than 100 countries). 

But critics highlight the issue that the most effective control, early containment, failed utterly, and that just in the wake of the lessons from COVID-19, casting doubts on future outbreak control efforts with more dangerous infections.

That's interesting, I had not realised the extent of the outbreak internationally. But it went away on its own, apparently. At least, I don't recall any vaccination effort being publicised. I had thought that was because the transmission process was not such as to enable an exponential spread, so it became self-limiting.   

2 minutes ago, swansont said:

I’m saying if you lift something with a magnet, you are supplying the energy, not the magnet. It’s not different, conceptually, from attaching a chain to something and lifting it. The chain is involved, but it’s not supplying the effort to lift the object. The chain doesn’t have a store of energy that does the lifting.

It doesn’t matter how convoluted or clever a scenario you come up with. The energy to do the lifting (which is what work is, in physics - the energy supplied by exerting a force through a displacement) comes from somewhere else. 

 

Indeed. However, But when a magnet and something attracted by it move closer together, under the influence of the force of attraction between them, work is done. I am saying this comes from  a reduction in the stored energy in the magnetic field. 

2 hours ago, Prajna said:

This is a much more reasonable response, @exchemist, thank you. At least you understand what I'm talking about. So what is happening is that there is a movement of energy into and out of the magnetic field, much like storing energy in an inductor, I guess. That's what I was referring to as 'work', perhaps inaccurately. We might consider that the steel sheet is 'falling upwards' towards the magnet in its magnetic field, that when the steel sheet is on the table and the magnet is fixed 30mm above it there is a potential energy imposed by the magnetic field and when the steel is attracted up to the magnet then that magnetically induced potential energy is converted to kinetic energy until the steel sticks to the magnet. Now the magnetic potential energy has been converted to gravitational potential energy. Then if the magnet is an electromagnet and we cut the current to it the steel falls to the table, a conversion of gravitational potential energy to kinetic energy until the steel rests on the table again. Have I understood correctly?

As an aside, I used to live in Chatham, Chattenden and Maidstone when I was at RSME and serving in the Royal Engineers. I spent a good deal of time at the Historic Dockyard in Chatham, where I drove steam cranes on the docks at the weekends. So I'm quite familiar with the area. That place is very interesting too. If you get a chance to visit the Officer's Mess at the dockyard you can see the vaulted ceiling that was built by ship's carpenters and is really the upside-down hull of a ship. 

Interesting about Chatham. I was surprised to see from the castle battlements an old (decommissioned?) submarine moored in the river, just downstream of the bridges carrying the railway and road. I might pop down the line from Victoria again some time and take a look. I think it's the next stop after Rochester. 

Back on the topic, yes there will be work done when the magnet and steel object move relative to one another under the influence of the force from the field. W= Fd, remember. But when the magnet is static, held to the beam by its magnetism, no work is being done. I think that is what @swansont meant by saying magnets don't do work, i.e. they don't do work when they are just sitting there, simply by virtue of being magnets, as it were! 

And there is no inexhaustible store of energy in a permanent magnet that you can draw on by incorporating it in a  perpetual motion machine. There is finite (fairly small) energy imparted to it when it is magnetised and you can get a bit of that back, once only, by allowing an object to be drawn towards it. But if you separate them again as part of an operating cycle of some machine, you have to put the same energy back each time. So as I say, no free lunch.  

4 minutes ago, sethoflagos said:

Either of the two main smallpox vaccines can control it, so if it were perceived as important (eg by killing white people instead), it would be easy enough to deal with. 

We get the odd case here from time to time. Nature's way of telling us not to mess around with rope squirrels (suspected wild reservoir).

Yes I think I recall smallpox vaccine was the solution last time it started to spread in a few Western countries. But it fizzled out pretty quickly, with or without vaccination. We had a few eyeball-rolling hysterics who thought it was armageddon, but it was a false alarm. It's going to take more than an article in the Daily Batshitograph (as I'm afraid it has now become) to get me to take this new story very seriously.  

5 minutes ago, Wigberto Marciaga said:

A mutant virus similar to monkeypox has been detected in the Congo, Africa (called: clade 1b). In fact, it has been classified as a new strain of mpox.

Experts believe that it has the potential to become a pandemic.

Mpox previously caused a global epidemic, highlighting its virulence capacity.

Experts call for quick action to stop the spread of the virus.

Let us remember that the majority of deaths from Mpox are children, despite the virus being related to sexual activities.

Reference: https://www.telegraph.co.uk/global-health/science-and-disease/mpox-outbreak-kamituga-democratic-republic-of-congo-africa/

There was a minor outbreak of monkeypox recently, but I’m not aware it became a recognised epidemic. As I recall, there was no more than a few hundred cases.

14 hours ago, Prajna said:

Ah, I hadn't seen this, perhaps it was edited in after I read your post. Thanks for the correction on Ed's name, I should really have looked it up. Yes, fascinating guy. He did some seemingly miraculous things and free-energy-cranks have been arguing over his book(s) for years, suggesting they were written in cipher, maybe they were. I rather thought that if anyone would be considered a crank then Ed would be right up there. Nice to be disabused regarding that.

Your curious fact is indeed curious, or certainly interesting. Whether I have enough interest to wade deep into relativity and QM to see it is another matter. If you can point me to general info about it that doesn't involve glazing over with esoteric formulae then I would certainly like to read it.

I explained exactly that the magnet is fixed. Maybe it's been there for years. Did I suggest, insinuate or even hint that it's floating? Eddy currents? What does that have to do with my question? I want to know what, in the circumstances I described, causes the increase in the potential energy in the steel sheet that is attracted to a magnet positioned above it. Just that. Answer that. Simply and clearly and without diversion, obfuscation or irrelevance. Can you do that?

I was out yesterday (visiting Rochester, on the Medway, a very interesting town with a Norman castle, a c.12th cathedral and a rather fine old high street with a lot of history) so have only just seen this. 

A permanent magnet has energy in its magnetic field. This energy was imparted when the magnet was first magnetised, aligning the magnetic dipoles of the atoms. A permanent magnet is thus in a metastable, higher energy, state, compared to one that has become demagnetised. What happens when a piece of paramagnetic or ferromagnetic material comes under the influence of this field is a bit complicated but I think in energy terms it is something like the following:-

The magnetic dipoles in that material are induced by the field to align with it. This costs energy, relative to the previous field-free, non-aligned state and the energy required comes from the field of the permanent magnet. So there has been a potential energy transfer from the permanent magnet to the material that is being attracted to it. The potential energy of the system can be further lowered by allowing the two objects to move together. It is the stored energy in the field of the permanent magnet that is responsible. (This is made clear when you consider the work you have to do to pull the two objects apart.)

But any repeated process involving separating and moving together permanent magnets simply moves energy into and out of the field. Energy can only be extracted from it once, in the phase in which they move together. After this there is no free lunch.   

20 hours ago, KJW said:

By "brighter", I mean "higher intensity". It should be noted that black body radiation is not just a frequency distribution but also an intensity, and that any radiation that deviates from black body radiation, either by frequency distribution or by intensity, is radiation that can do work. In the case of the perpetual motion machine, the ability to focus black body radiation from an object into a smaller space increases the intensity of the image so that it is no longer black body radiation and can do work.

If one wishes to capture the entire radiation output of a small spherical object as an image, one can place the object at the focus of an internally reflective prolate spheroid. The image forms at the other focus. But note that symmetry demands that the image is the same size as the object, and hence the same intensity. On the other hand, if one uses a magnifying glass to focus sunlight onto a piece of paper, the image is much smaller than the sun, but then one is capturing only a tiny proportion of the total output of the sun.

 

 

Yes I suppose that makes sense. Does it make sense, I wonder, to speak of the radiation distribution having an entropy? What you seem to suggest is that the black body distribution has the maximum entropy of any radiation distribution.

1 minute ago, Prajna said:

Well, I don't claim it to be a comprehensive explanation (just that the one I outlined above is more complete than the previous offering). I'm trying to present a (albeit much simplified) way of looking at magnetism that, perhaps, helps to understand what is happening with magnets. Thanks for the pointer to the wiki article, very interesting, particularly the idea of gyrators, which I had not come across previously. Gyroscopic effects being another favourite of free energy cranks, btw.

The idea of pole coincidence is to explain how a magnet comes into existence and, in my model, represents the 'ideal' state of a material, exhibiting no magnetic properties outside the material itself. When the poles become separated, by whatever means, the material is constantly trying to return to that ideal state with its poles again coincident. If it can't do that then the next best thing is for it to complete its magnetic circuit in the most efficient manner - by the shortest, lowest reluctance path, including by attracting any ferromagnetic material in its local environment into a position where it offers the shortest path for the 'outside leg' of the circuit.

Sure, this description doesn't attempt to reconcile with other models of EMF and MMF and falls short of attempting to incorporate formulae with which to quantify it, but it is simple and sufficient to understand magnetism on a broad level, much as using water flow in a plumbing system to illustrate the principles of electric circuits.

Using it I can explain the interaction between the fingers on my rotor and the opposed magnetic poles in the rocker magnets by saying that when a finger is interposed between the magnets the magnets are offered a path by which they can reduce the stress in their magnetic fields by taking the path offered by the ferromagnetic properties of the finger - lower reluctance and a shorter path for the 'outside leg' of the magnets - thus attracting to the finger where they were otherwise repelling each other. It may not be a 'scientific' explanation but it is not 'wrong'.

Perhaps a short digression into the philosophy of science is appropriate. Science develops models of nature that enable correct predictions of the behaviour of nature to be made. Very often these models are recognised as approximate or incomplete and thus to have a certain scope of application which should not be exceeded. Newtonian mechanics is a good example. Nobody says Newtonian mechanics is "wrong" but it doesn't work at the atomic scale, nor when relative speeds are a significant fraction of c. We all know this and use Newtonian mechanics with those limits in mind. The magnetic circuit model is evidently quite successful for many engineering purposes, provided one doesn't stretch the analogy of its fictitious magnetic "current" too far. It is a scientific model insofar as it makes correct predictions for how nature will behave.

If your model tells you a static magnet continually does work, though,  you have a major problem, because you need to explain where this energy appears, what its source is and why this source never runs out. So at that point your model fails. 

12 hours ago, KJW said:

The design to which I am referring was also a perpetual motion machine of the 2nd kind. It consisted of a large diameter pipe radiating thermal radiation at room temperature, this radiation being focused onto a smaller diameter pipe, the increased intensity resulting in an elevated temperature of the smaller diameter pipe. I could see nothing wrong with this design and was forced to conclude that it is impossible to focus radiation to an image that is brighter than the source. I raised this on a forum I regularly visited at the time, and my hypothesis was confirmed by another member.

 

I suppose that depends on what is meant by "brighter". In terms of radiation intensity, I'd have thought one could increase that beyond the intensity of the source, if it is an extended source. But clearly one can't change the frequency of the photons merely by focusing a beam, so the effective temperature (if is black body radiation) of the radiation can't be altered. in that way. Is that what you meant? 

43 minutes ago, Prajna said:

Ok, I'll get on to reading that wiki article shortly but let me first attempt to outline more clearly and completely my theory (rather hypothesis) on magnetism:

1. All matter contains two magnetic poles that normally coincide.

2. In some substances it is possible to separate the magnetic poles in which case a 'magnet' is created. (perhaps this is possible with all substances, just we don't know how to do it yet). In ferrous metals, for instance, we can do this by exposing them to a magnetic field. I'm talking here on a macro level, there may be a far more adequate description at the atomic scale, your description of the alignment of magnetic domains being an example, but let's stick to considering it at the level of magnetic circuits for the moment.

3. When a magnet is created by separating the normally coincident poles a magnetic current is created, one 'leg' of which circuit runs between the two poles inside the, now, magnetic material. The other leg tries to complete the circuit via the shortest, lowest reluctance path it can find, normally the air surrounding the magnet,though this is a very high reluctance path but if there is no better path then it will do that; the circuit has to be complete whatever the circumstances are, you can't have an open magnetic circuit, according to my theory, which is why a monopole cannot exist (except I recently noticed an article that suggested magnetic monopoles have been created, oh well, maybe).

4. If the magnet, with its magnetic stress from the pole separation, is close to something that offers a lower reluctance path than the air then the magnet will try to include that object in its circuit, attracting said object to itself in order to shorten the path: what we see as magnetic attraction.

5. When we bring two magnets together with like poles  facing both magnets we have really joined both circuits so that there are now four 'legs' to the circuit: the shortest, lowest reluctance legs running between the two poles in each separate magnet; the high reluctance, longest leg, between the extreme ends of the two magnets; and a leg interposed between the two magnets.

6. When we bring two opposite poles together what we are really doing is adding to the magnetic stress in the magnets, effectively further separating their magnetic poles. Now each magnet finds it more difficult to complete its circuit since the 'like' pole is adding to the reluctance in the 'outside' leg.

So the magnet sticking to the beam is explained by the magnet trying to incorporate a low reluctance path and make that path as short as possible. For any faults this explanation contains, for me at least, it offers a useful way of understanding the behaviour of magnets. If it makes me look like a berk then no matter, I'm sure there is always a place for a free-energy-berk-crank, at least in some people's affections.

(was replying via my phone earlier, which is why my explanation was less clear)

Apart from the bit about separating coincident poles, which seems to make little sense, this may work fine for you, for macroscopic magnetic or magnetised objects. The weakness is it can't connect macroscopic behaviour to what goes on at the atomic level or connect magnetism to other scientific phenomena. So it's basically reverting to a c.19th, pre-atomic theory, picture.  I've seen this before with some people from an engineering background on science forums. I suppose they prefer the mastery of nature which c.19th physics seemed to achieve, before the inconvenience of the invariance of the speed of light, the ultraviolet catastrophe and the photo-electric effect forced a rethink.

If you are happy with staying in a sort of steampunk, H G Wells era world, well OK. Most of us prefer deeper explanations, that connect to other scientific phenomena.

1 hour ago, Prajna said:

Ok, I hadn't really associated chemical bonds with electrostatics (which I tend to associate with Van de Graff generators and rubbing cats on perspex rods, etc) but I'll accept that chemical bonds are electrostatic.

All the thinking about this device began while watching one of Robert Murray-Smith's early videos where he was discussing Wesley Gary's magnetic motor. He showed that if you place a thin keeper across the poles of a horseshoe magnet then if the keeper is longer than the span between the poles you will get additional poles that appear on the ends of the keeper due to flux leakage. If you then lift one end of the keeper off its pole the pole on the end of the keeper reverses.

The way I interpret what is happening with the keeper is by thinking in terms of magnetic currents. As I see it, a magnet is always trying to close its circuit. Really it is a perpetual motion machine all by itself. There is a large magnetic reluctance in the air but the magnet will complete the circuit will complete itself via the air if there is no path with more permittivity available. The keeper offers a low reluctance path but if it is too thin to contain the full magnetic current then some leaks through the air surrounding the keeper. That leakage flux will be of the same polarity as the pole it is next to. When one end of the keeper is lifted off its pole you have effectively turned your magnet-and-keeper into one long bar magnet (or a kinky horseshoe magnet in this case) and the keeper becomes one end of that magnet - the opposite pole to the one it presented due to leakage flux.

In my terms, a magnet will attract any object that offers a lower reluctance path than whatever is allowing it to complete its circuit currently (if you'll excuse the pun), that a magnet always completes its circuit via the shortest path with the lowest reluctance and the circuit is always closed. This need to reduce the length and reluctance of the magnet's circuit is what we observe as magnetic attraction.

Now this understanding of magnetism may well be wrongheaded but it seems to me to offer a much better description of magnetism than the classical scientific one you offered, which doesn't really tell us anything about how magnets behave.

I think Ed Leedskillin was the only guy who understood magnets but then nobody can understand Leedskillin (including me.)

OK I understand what you mean and I'm aware there is a "magnetic circuit" model used in engineering: https://en.wikipedia.org/wiki/Magnetic_circuit 

However this has drawbacks if used incautiously, as is in fact mentioned in the article. There is in truth no magnetic "current", as nothing flows. Whilst we habitually draw flux lines with arrows on, these do not indicate a flow of anything. The magnetic field is a vector field, i.e. it has both a magnitude and a direction at any point in space. The density of flux lines is used to denote magnitude and the arrows denote direction. That is all the arrows mean. A field is not a current. (This is explicitly stated in the section of the Wiki article subtitled "limitations".)

As for whether this way of thinking of magnetism is a better description, we have just seen how it has given you the wrong answer, in the example of the magnet stuck to a beam. So clearly it has severe limitations. The circuit model may be fine for analysing the shape of the field in electrical machines and so forth but, as with many models in science, it has limits and if these are not borne in mind it can make you look a bit of a berk! 😀

I had not heard of Ed Leedskalnin (not Leedskillin), but I see he was a Latvian immigrant to the USA who was active in  magnetism between the wars. I also see that indeed he was on the right track in interpreting magnetism as arising from circulation of charges within the substance, just as I described to you in my previous post. His understanding was thus a foreshadowing of what we understand today about magnetism from atomic theory, quantum physics and quantum chemistry. (Quantum theory was developed in the late 1920s and 1930s, possibly a little later than when he was writing about magnetism.) 

P.S. Curious fact: magnetism can in fact be shown to arise as a consequence of applying the theory of special relativity to electric charges in relative motion. I think that is rather cool. 

30 minutes ago, Prajna said:

Hmmm... I still feel like I'm being fobbed off somewhat. I consider a screw as being 'held', as it were. Actually the object that is being held by the screw is exerting a force downwards, due to gravity, while that force is being countered by the cohesive forces of the screw and whatever it is attached to. Electrostatic forces must be established and maintained. Concrete supporting something can be intuitively understood, as with adhesion and the steel wire rope you referred to.

Magnetism does seem mysterious and different to other mechanical forces we encounter day to day, you can hardly blame free energy cranks for finding them irresistible. Thanks for the anecdotes of previous offenders, I'll have to look that old thread up.

I suppose that part of the difficulty is in differentiating between force, work and energy.

I’m a chemist by training, so I am very much aware that chemical bonding is electrostatic. Every solid object gains its solidity due to electrostatic attraction, between atomic nuclei and their surrounding cloud of electrons. It is this that bonds atoms together in solids. Magnetism is only different in that it arises from electric charges in relative motion. In a permanent magnet the atoms have unpaired electrons, which have angular momentum, circulating and/or “spinning” and this motion creates a magnetic dipole on each one. These align and their collective dipoles combine to create the magnetic field of the magnet. Unless it is an electromagnet, in which case, the field arises from the flow of electrons (electric current) in a coil of wire. 

2 hours ago, Prajna said:

Fair enough, however energy is being employed to sustain the weight of the magnet against the force of gravity (at least I accept that gravity exists, count your blessings, you could be talking to a flat earther rather than a simple free energy crank). As I say, were I to hold the magnet in the air I would hope to have tucked into a decent bowl of porridge before the task, certainly if it was a heavy magnet. So, excusing my technical ignorance on the subject for a moment, what's holding the magnet there and what's the energy accounting?

Magnetic attraction.

If you have a bolt screwed into the beam, all that holds it in place is actually electrostatic attraction, because that is what is responsible for the chemical bonding in the metal that enables it to keep its shape and resist deformation under stress. There is no difference in principle. 

Don't be fooled by how biological muscles work. Those do expend energy to hold a weight in a static position, but that's to do with the biochemistry of muscle fibres. 

My example of the bolt screwed into the beam is what you need to consider. That does not expend any energy, not even if the bolt supports a 1 tonne weight suspended from it! Or think of a concrete support holding up a weight. If you did that by your muscles, you would get tired, but the concrete is not doing any work to hold the weight up. Work is only done if something moves under the action of a force. So a crane lifting a weight does work against the force of gravity. But if the operator stops work for lunch and leaves the weight hanging there from the cable, no work is being done.  

So there's no energy accounting to do in the case of the magnet. A magnetic force or an electrostatic force can both equally hold something in position against the force of gravity, in the right circumstances. 

54 minutes ago, KJW said:

I'm strongly opposed to forum moderators locking threads about perpetual motion machines. I think perpetual motion machines can be interesting as well as instructive. I have even discovered an interesting principle as a result of considering a design that could be used to construct a perpetual motion machine:

Neither lenses nor mirrors can produce an image that is brighter than the source.

 

 

There have been a few on this forum. My favourite was Tom Booth's "ice engine". He got banned in the end but that was for failing to take in anything anybody said, not because he was proposing a perpetual motion machine. Unusually, that was a perpetual motion machine of the 2nd kind. But it was a crank classic in that it was all based on Tesla [groan]. I had not realised that among his many eccentricities, Tesla thought you could run a heat engine using ambient heat.

There was also, on another forum, aJapanese who thought an IR photovoltaic cell could be put in a fridge, light a bulb and cool the fridge. So that was another 2nd kind example.  

Tom Booth was interesting in that he had researched the history of thermodynamics and put me onto a paper by Sadi Carnot (in translation) in which he, Carnot, was applying the idea of caloric, i.e. before the modern concept of heat even existed, and nevertheless was able to get the right answers!   

10 minutes ago, swansont said:

I hope H didn’t stand for “Hugh”

That, we were all sure, was the intended joke. We hoped he would win , so that he would have to be announced at the prize-giving ceremony. Sadly, he got knocked out of the competition in one of the heats.

1 hour ago, Prajna said:

Interesting. Thanks for another considerate response. I'm very interested to have a play with it and get a feel for how it behaves. You may be right that some energy can be passed back, I'll investigate. Hopefully I will be able to visit FabLab on Wednesday to see if they can help out with some 3D printing, laser cutting and sourcing nuts, bolts and shafts.

It's not only 'free energy cranks' who don't understand magnetism. For instance, I've never seen a good explanation of what's going on when you stick a magnet to the bottom of an overhead steel beam. The magnet is obviously doing work, holding its own weight, certainly if I was holding up a magnet against the force of gravity it would feel like I'm doing work. So where's the energy coming from to do that work? If it's from the magnetic field then is the magnet's strength depleted by it? If not then why?

This comment of yours illustrates exactly what I feared about your grasp of physics when it comes to magnets. No work is done by a static magnet sticking to a beam.  Mechanical work is a force applied through a distance, F x d. You would not think a bolt screwed into the beam was continuously doing work by staying there, would you? So why do you imagine a magnet sticking to a beam is doing work?