- HubPages
*»* - Education and Science
*»* - Physics

# Larry's Take on the Claim that Gravity Is Magnetism

## Introduction: a thrilling experiment

Hub author Newton's Rival is a leading proponent of this view. One of her central assumptions is the existence of magnetic monopoles. I'm agnostic on this specific point. I'll be convinced when I can buy a jar of magnetic monopoles at Trader Joes. I prefer the chocolate ones.

In the meantime, I'll reframe the issue as follows: Is magnetism equivalent to mass?

We'll see that to a very limited extent, the answer is yes.

We'll attempt to shed some light on this question, without making assumptions about magnetic monopoles, and using only standard ideas from physics. Specifically, we'll apply electricity, magnetism, and Relativity theory. I'll try to keep this as accessible as possible for nonspecialists.

The experiment. First, cannibalize a step-up transformer from an old television. (Scrounging a transformer is much more sporting than buying a new one.) Then purchase an ordinary flashlight battery. Invite 10 of your friends over for the experiment.

Be sure to provide yummy snacks afterward. And be certain that all of these friends are in good health.

Ask your friends to stand in a half-circle, and instruct each person to hold hands with his/her neighbor or neighbors. Have Person #1 hold one lead from the secondary of the transformer. Have Person #10 grasp the other secondary lead.

Duct-tape one of the primary leads of the transformer to one terminal of the battery. Hold the other primary lead of the transformer against the other terminal of the battery for several seconds. Then abruptly lift that primary lead from the battery.

The result: Each of the 10 people will receive a mild electric shock.

The explanation. The DC from the battery, plus the primary winding of the transformer, plus the iron core of the transformer create an electromagnet. It's magnetic field stores energy, and releases that energy when the magnetic field collapses. We'll see why this is relevant in the next two sections.

## A few words about Relativity

One of Albert Einstein's best-known ideas is energy-matter equivalence. This can be expressed mathematically, as follows:

E = mc^2

The equation allows you to calculate energy-matter equivalences. Here's a typical example.

In a nuclear power plant, suppose that the fuel rods lose 1 microgram of mass in a certain amount of time.

Using Einstein's equation, you can easily calculate the amount of energy that was released in the process.

Nuclear energy is one common application for Einstein's famous idea. It must be emphasized that the equation applies to all forms of energy, even though the effects are sometimes too small to measure accurately.

Suppose that you pan for gold as a hobby, and that you keep a nugget in a small vial inside your refrigerator. Take it out and measure the mass on a laboratory balance. Then set it out in your backyard in the Summer sun for an hour. It will acquire some heat energy. If you measure the mass again, Einstein's famous equation predicts that the mass will increase by a small amount.

The catch is that the tiny mass increase will be extremely difficult to measure. However physicists have been testing the predictions made by Relativity for many years. And for medium-sized objects, the results are always within the range of experimental error. This does not prove that Relativity is 100% true, 100% of the time, everywhere in the universe. Nevertheless, as far as scientific theories go, it's a pretty good one.

I'm reasonably confident in the Relativity prediction about the gold nugget. And this thought-experiment predicts a heat-mass equivalence, which is a special case of energy-matter equivalence.

## The upshot

Using the same logic, we can demonstrate a theoretical equivalence between mass and magnetic fields. Other things being equal, an electromagnet with a DC current flowing through the coil will have a slightly stronger gravitational pull than it did before we applied the current. Why?

Our thrilling experiment shows that a magnetic field can store energy. The theory of Relativity predicts that the energy stored in this magnetic field has a mass equivalent. But the effect is so small that it's extremely difficult to measure. Getting back to the original question, is magnetism equivalent to gravity? In terms of our present knowledge, the short answer is: To a very limited extent, yes.

Here's a link to the hub by Newton's Rival on the subject:

http://hubpages.com/hub/Gravity-is-Magnetism

## Addendum 10-25-11

There's been some informed speculation about exotic ways to generate gravitational fields. The hypothetical electromagnetic geon is an example. Quoting from the wikipedia article:

"In theoretical general relativity, a geon is an electromagnetic or gravitational wave which is held together in a confined region by the gravitational attraction of its own field energy. They were first investigated theoretically in 1955 by J. A. Wheeler, who coined the term as a contraction of 'gravitational electromagnetic entity.'"

http://en.wikipedia.org/wiki/Geon_%28physics%29

Since 1955, other physicists have pointed out at least one potential fly in the ointment: If electromagnetic geons can be created, they may be very leaky, and may decay quickly.

However this may not be the case for geon Black Holes, in which a sufficient amount of electromagnetic mass-equivalence is stuffed into a sufficiently small volume, such that the escape velocity is greater than the speed of light, and nothing can escape--not even light.

I don't know how much traction the geon meme has had over the decades in the physics community. And for the record, I must state that I don't believe in Black Holes. I'm simply mentioning that possibility for the sake of completeness.

Copyright 2011 and 2013 by Larry Fields

## Comments

"Be sure to provide yummy snacks afterwards. Also be certain that all of these friends are in good health." Too fricken funny! Love it, fantastic hub. I am extremely interested to hear responses, and the way you wrote it and laid it out... Exquisite. Thank You!

From a physicist mate: "The potential existence of magnetic monopoles is a problem that arises in GUT of the fundamental physical forces. It they exist in significant numbers, they would drastically slow the expansion of the universe, which is not what is observed." I am waiting on more expert input.

Grand Unified Theory(ies)

I am with Larry, can you explain GUT to us better please? : )

Hey Larry, what morons are we??? GUT... Grand Unified Theory! lol!!! However, his statement is that if magnetic monopoles exist in significant numbers they would drastically slow the expansion of the universe, which is what we are not observing, Now.... My curiosity is, how do we know what is considered "slow" or fast expansion of the universe. Is there some set standard? How do we know that what we think of as fast is in all actuality slow?

I suppose we must wait for Manna to answer, : )

The ultimate goal is to find a unification theory that explains all observed particles and forces as one single system. String theories, GUTs are considered stepping-stones to this goal. So from that perspective, magnetism and gravity would be combined with the other forces into a single explanation. I can't quite say "gravity is magnetism" any more than we can say "electricity is magnetism" even though the theory of electro-magnetism is well proven. Gravity has been frustratingly and tenaciously resisting unification with the other forces because it is so different. The one spot where classical and relativistic treatments of gravity come together with particle physics, is at and around black holes.

In a way, a black hole is a consequence of a breakdown in general relativity. Space-time ceases to behave itself according to the equations. When you look at these particular solutions of GR, what you find is that black holes are posited because the finite numerator of an expression is divided by zero. Division by zero in any number system from integers to complex numbers, and also in 4-D Minkowski space which is the playground of GR, is nonsense, so "at" a black hole, the GR theory breaks down, effectively we don't have a theory of space-time at that point.

A point is a dimensionless concept useful in pure maths and for approximating models in the real world. Many working and successful predictions about real systems can be made on appropriate scales by assuming thinks like 'a point charge' where is actual reality this might not quite be true. As a physicist you need to know when it is appropriate to make approximations like this.

Much of particle theory uses point-particles and does very well, but breaks-down in annoying ways under certain scenarios.

This is where string theory comes in. Point particles are replaced by things with dimension. Very tiny closed loops and open strings. Objections to this idea is that these things have to be far smaller than the planck-length and hence unobservable, and perhaps a theory that is untestable. Additionally, in order to formulate the maths that explains observed (and predicted particles), theory demands more than 4 dimensions to permit enough degrees of freedom. The problem with that step is there are zillions of solutions to the equations, and even several (5) different views of the same theory. M-theory explains the equivalence of these 5 views (Ed Witten).

For a long time, scientists laughed at string theorists, and if you wanted funding, then you did not enter into that field. But it has had a resurgence, and today, many consider that it is a good candidate for a "TOE" (Theory of everything). These string theories, GUTs and the standard model do explain a lot of observable phenomena, but they also make predictions (Like the Higgs field and the Higg-Boson). Luckily those kind of predictions are testable. The Large Hadron Collider is one such effort to support (or disprove) many of the contending theories.

Magnetic monopoles are a part (prediction) of GUTs. Observations of the cosmos tell us, through well tested means that space itself is expanding at a measurable rate.

Models of the universe from big-bang to present day based on various theories agree and predict this expansion rate. But when you throw in significant numbers of magnetic monopoles into the equations and models, then the predicted expansion rate no longer agrees with observation. It's independent of what is meant by 'slow' or 'fast'. This is a comparison between a promising mathematical model and observation.

Ahhhh, speaking of the Hadron Collider, could you please be so kind as to explain to us how exactly this piece of scientific equipment works. Besides the overall outcome of smashing together atoms of course. How exactly does it function ?

Really I am just interested in the the process and components that make the Collider actually work. How do they go about making the collider able to smash these atoms? In truthfulness I already know the answer... Just would like to hear it from you. Another coincidence?

I agree with all of your points in the main part of this hub. I disagree that magnetism *is* gravity. I'd like to make it clear that I do understand that a unification of all the forces might be possible. But, like squeezing toothpaste out of a tube, you can't get it back in... when the conditions under which unification exists change and symmetry breaks, then the forces that we can measure, and the fields used to explain them are then distinct. Really, if you want to say "gravity is magnetism", then why not gravity is electricity, or gravity is electro-magnetism, or (since electro-magnetism has been unified in GUTs) with the weak sub nuclear interaction, and the strong nuclear force, then say "gravity is electromagnetism-weak-nuclear-interaction-strong-nuclear-force" - If "gravity IS magnetism as claimed" don't you think that conclusion would pop out in these theories?

Yes - absolutely agree on the science-economics front - and also the cut-throat sometimes scathing and nasty peer-reviews. It's really hard to go against mainstream established ideas even if you have the qualifications and the experience, and a testable coherent theory. Read

nohiggs.wordpress.com - an interview with Eliyahu Comay as a class example. He may well be on to something but is ignored by the scientific community because the standard model is now so well accepted. I've yet to read all of what's there.

Note that Comay challenges well established theory (I think for good reason) but still won't go near breaking Newton or thermodynamic laws. "Newton's Rival" will be particularly interested in his model for the attraction between a quark and antiquark. Whether he is right or not, I don't know - but he does offer a testable theory, and suggests an experiment.

As for "black holes don't exist". That might be true. In fact as mentioned, they arise as an excuse for a breakdown in GR. I am not aware of any observations that suggest G is not a universal constant but it's a big universe!

It would be nice if a different coordinate set could rid GR of these problems. However, there is now quite a lot of experimental and independent supporting evidence for black holes. If G is not constant, then it seems reasonable that it could modify our accepted physics as an object approaches the so called singularity to avoid that nasty 'infinite density' problem that is a black hole but even so I'd guess that 'infinite' would be replaced by some gigantic number instead. Good luck to your friend.

I sort of know what might be involved comparing the idea of a black hole to what is called a 'pole' - used in amplifier and oscillator design. We happily look for divisions by zero to indicate stability criteria and feedback conditions in control theory. When the transfer function approaches a division by zero, the transfer function heads off to infinity. Mathematically, these points are undefined and cannot exist in reality. Yet we go ahead and build the amplifier anyway. In reality, of course, the transfer function is not infinity at that point because the model is just an approximation. If we had a more accurate model, then we could compute what really happens at those points. There would still be a pole-like function but it would not go to infinity in practice. However, for the purposes of amplifier design the inaccuracy is not important. Using a more complex model would just make things more difficult to calculate for the same end result.

No - I don't think you went off topic.

On a side note... since NR's hub brings antimatter into play, we don't see antimatter floating about. In fact, since matter and antimatter annihilate, it's a puzzle that there is any matter left for us and what we see. (At least in our part of the universe). This asymmetry is a puzzle but there is a recent idea that the rotation of our galaxy could explain it, and the explanation is a doozie. GR predicts that a rotating massive object will drag space-time around with it (not much - but a galaxy has a lot of mass). Frame-dragging like this could cause a time dilation such that anti-matter decays slightly quicker than matter which could explain why we only have matter today.

Anti-matter is real and we can produce it but not store it. In fact the medical imagine machine, a positron imaging tomography relies on it.

Awwww, screw it, here ... I'll put it here for you guy's...The collider tunnel contains two adjacent parallel beam pipes that intersect at four points, each containing a proton beam, which travel in opposite directions around the ring. Some 1,232 dipole magnets keep the beams on their circular path, while an additional 392 quadrupole magnets are used to keep the beams focused, in order to maximize the chances of interaction between the particles in the four intersection points, where the two beams will cross. In total, over 1,600 superconducting magnets are installed, with most weighing over 27 tonnes. Approximately 96 tonnes of liquid helium is needed to keep the magnets, made of copper-clad niobium-titanium, at their operating temperature of 1.9 K (?271.25 °C), making the LHC the largest cryogenic facility in the world at liquid helium temperature. now... I can't help but to notice that the Collider's main function is to damn near put forth our best earthly efforts to recreate the universe's functions, yet the word magnet comes up so very much in the way this thing was made. I think we'd be safe in saying it's "scientific fact" that magnetism HAS to be a key element here and no one find's that just the least bit odd?

Manna.... you stated..."Magnetic monopoles are a part (prediction) of GUTs. Observations of the cosmos tell us, through well tested means that space itself is expanding at a measurable rate.

Models of the universe from big-bang to present day based on various theories agree and predict this expansion rate. But when you throw in significant numbers of magnetic monopoles into the equations and models, then the predicted expansion rate no longer agrees with observation. It's independent of what is meant by 'slow' or 'fast'. This is a comparison between a promising mathematical model and observation." ... Agreed obviously space is expanding at a measurable rate, but then you stated "when you throw in a significant number of magnetic monopoles into the equation,the "PREDICTED" expansion rate no longer agrees with observation. How can One say that? What if your not taking into consideration that these significant number of magnetic monopoles, ARE ALREADY factored into the equations. They are already part of the universe's expansion rate? No testing has ever been done to prove or disprove this...Who is to say they are not already part of the universe's expansion rate, and by adding ANOTHER significant amount compared to what is already there, that is what is actually throwing off the calculations?

Also forgive me if my prior comments seem a little "attitudish" : ) not meant that way. I'm just wide eyed and bushy tailed at 5:45 a.m. , that's when I do my best thinking, early morning, or as I'm drifting off to sleep. At the current moment my mind is racing. What I want to know is this... Is there some kind of experiment that any one can think of, using my theory and based on my theory, not what we think we already presently know, but something that can undoubtedly prove or disprove my theory? I'm not talking about a million dollar experiment , lol. I mean something more of a lab-like-setting? I know already and we have already proven that zero gravity can in fact be reached by putting any object in a strong magnetic field. However, I want to do something that is more natural, something ppl cannot dispute as "other outside manufactured factors" . I realize the difficulty in thinking of one like this, believe me, I've been trying to think of one myself for a very long time now. Maybe someone outside the picture unlike myself can see what I can't as an idea?

Boy O boy.... wouldn't it be nice if Einstein just rose from the dead, and did all this figuring for us ? lol!

Just a thought that I would like responses to, First please watch this video,.http://www.youtube.com/watch?v=C3DD33ZZ6Co&fea... then after watching this video read this short article.

http://www.rikenresearch.riken.jp/eng/research/624...

I'm wondering, is it possible that our sun is in all actuality a trapped monopole on the end of a much much bigger dipole? and the spin of our galaxy is nothing more than what trapped monopoles do, SPIN! Like a spiral! I'm just curious what you guys think, is this possible?

There are several things to comment on here. I'll try to get to them one at a time. The first is, that if your theory predicts effects on the Earth from the sun, and as Larry points out the sun swaps poles frequently, then whatever effects on the Earth that you predict should happen as a result of magnetism should coincide with the events on the sun. If they don't, then how do you explain that? What effects did we see here on Earth just before Feb 2001 when the sun did a flip? You have another chance to check it next year.

The Sun's magnetic field strength is about 50 Gauss which rivals that of a fridge magnet. The Earth's is 100 times weaker. (NASA data)

You did a great LHC description by they way. Magnets feature there a lot because gravity is not magnetism. They need to force particles into a circular trajectory in order to speed them up over lots of rotations. If non-charged particles used then you would need to deflect them with a massive gravitational force. We can't create that but we can create an intense magnetic field to act on charged particles.

I'm interested in your idea for an experiment.

I watched the video -- up to 95% of it anyway then got annoyed with it. He totally confuses electric charge, electrons, and holes and electron-hole recombination, and posits an unsubstantiated incorrect idea about magnetic monopoles floating away as some kind of excess for some hand-waving reason. All the while he is describing a normal off the shelf dipole magnet and a primary school experiment and doing it extremely poorly.

If one could buy a jar of monopoles, then I'd like a few. It should be possible to create energy from nowhere. All you would need is to have a wheel where the spokes are N monopoles and then push the wheel around with another stationary N monopole. Countless people have tried to make a perpetual motion machine -- often using (dipole of course) magnets, and failed.

Your theory says that gravity = magnetism. Since gravity is known to bend light, then magnetism should also bend light.

Another experiment one could do is with a laser. Shine the laser onto a distant spot, then offer up a powerful magnet close to the beam, near the source. Does the spot move position? No? Try using two different coloured lasers and send the beam to the same spot. Introduce the magnet near one beam and look for colour change or fringing around the spot. Does it change at all? Even a little bit?

If gravity = magnetism, then how could you do this: http://www.youtube.com/watch?v=vsQh1AT6qUE with gravity?

Hi, I just read http://www.rikenresearch.riken.jp/eng/research/624... and found this very interesting and curious. Am not sure how it supports your theory or if it was flagged to do so.

NR: in your hub, early on, you say, "The South pole of the earth is always tilted more towards the sun" Do you still think this is true?

If you have the patience, it's worth watching all of www.youtube.com/watch?v=yINtzw63Knc

This video shows the unification of the electric and magnetic fields. If you can't follow the maths, I am not sure what you will get from it, but what he says should make a lot of sense. Towards the end, it shows a theoretical calculation of the speed of an electromagnetic wave in free space, and also the speed of light (since light is an EM wave), and also the relationship in 3D between the magnetic and electric field. Newton's laws are embedded in the derivation because of the wave-equation. The final conclusion to the video is that for non-relativistic charge motion, most of the force is provided by the electric field. This is true for electrons is wires for example. But for high energy particle physics, and astrophysics where charged particles can travel near the speed of light, the contribution of the magnetic field is comparable to that of the electric field.

If someone was to prove the existence of magnetic monopoles, then Maxwell's equations could be made more symmetrical because Gauss's law for magnetism would not universally equate to zero, in fact it would be symmetrical with Gauss's law for electric charge. We would be able to talk about the motions of magnetic "charges" - not sure what you would call them "marges" perhaps?

A dipole magnet send lines of magnetic flux always in a loop. The line integral is zero. The net work that you can do with it in attempted perpetual motion machines is zero. But a monopole has to send the flux forever away into space and you would get a gradient which could be used to prevent the line integral from being zero.

In my opinion, if magnetic monopoles are found, then there will be severe conditions on their existence to avoid breaking the law of conservation of energy.

Sure - we could add symmetry to Maxwell's equations, but that symmetry would have to be broken when the special conditions for magnetic monopoles are not applicable.

Sorry - that should be the surface integral - same conclusion though.

Larry, you said "That hypothetical monopole application is probably correct," Honestly though, I;m not so sure about the configuration of that hypothetical engine (It might need to be more complex), but reasonably confident about breaking conservation of energy.

Even in the GUTs, magnetic monopoles would only exist in the very early hot instant of the big bang.

Dirac monopoles are infinitely long, infinitely thin, have one end at infinity, the other end planted somewhere, and are unobservable. These don't seem practically useful and as I said before might be a mathematical tool rather than a real physical state.

Here is a much better description of a bar magnet, and a very clear description of Maxwell's equations. http://www.youtube.com/watch?v=h5Y45wEO9F4

Spent the day working, I see there's a lot to catch up on. The laser light bending experiment sounds interesting too. I'll have to read all the comments and then the links provided. I'll get back tomorrow. Night guys!

NR: One important concept about electro-magnetism is that the energy in the magnetic field transfers to the Electric Field, and back again, and so on. Magnetism and electricity are part of the same phenomenon, but they are different fields. Gravity is an intrinsic property of matter. Everything with mass, whether it is rest-mass, relativistic mass, or both "suffer" attraction. There is no way to shield gravity but you can shield an electromagnetic wave. The sun would squish up under its own gravity were it not for the outward nuclear kinetic forces produced by fusion. Due to its particular size, as it burns its fuel over time it will become lighter, hence bigger and eventually engulf the Earth.

@ Manna, only in regards to your last post as i have just awoken and not read through the rest yet... I beg to differ , Gravity is not a property of matter. If this was proven accurate the long sought after Graviton would have been produced by now. Yet we still wait for proof of it's existence. Don't you think that as powerful as the Hadron is, they should be looking for that? As for shielding it, First one must know what type of magnetism we are dealing with. Only then can we counter it!

I'm trying to find out more about this perpetual motion machine - I could be wrong about magnetic monopoles and violation of conservation of energy.

NR: There is only one type of magnetism. You can do the shielding experiment on the table top with a magnet, a nail, and some soft iron sheet. Place the iron sheet between the magnet and the nail, and the nail will no longer be attracted.

The graviton is not in any way practically directly observable. However, there are experiments under way to detect gravitational waves. The speed of these waves will tell us about the mass of the graviton. If it is (as expected) light-speed, then the graviton (as expected) will have zero rest mass. Otherwise, it will be an exciting time. Gravity waves are very very very very weak and difficult to detect. This is why they have not yet been detected. Despite this, all classical Newtonian theory demands that gravity is a long-range universal attractive force that cannot be shielded, inherent in the mass of the thing under test. In GR, it is not a force at all, but a distortion of space-time. In GR, electro-magnetism is a wave that travels though space-time, following the path of least distance between A and B, which will be a curve near a mass because of the distortions. In Newton's theory, and in GR, "Gravity is NOT magnetism."

Did Manna just say he could be wrong about at least one little thing? lol! Impressive. (joking)

Hi Larry. The flux is contained within the metal, you are correct. It's still a shield, something you can't do to gravity. If you find a real magic carpet on ebay or something, I'll change my mind.

Cancelling is something different, and can also be applied to an E.M wave (as shown in an interference pattern).

There is no way to 'cancel' gravity, at least on any scale that we can experience. We are stuck with it.

NR: Yup - I get things wrong at times and happy to admit it. In fact the best time is finding when I am wrong and then improving my knowledge.

Indirectly, these discussions has lead me to a better understanding of special relativity, so thanks for that.

I would like to make a few comments.

1. Long math equations do not mean truth.

2. Resolved equations do not mean the theory proposed is correct

3. It is hubris to think one CAN know all things. The universe is actually (as far as we know) infinite, humans never will be.

4. When the math breaks down like in the theory of Black Holes, I find it funny to accept the 'reality' of 'black holes' and, at THAT point (quite arbitrary, if you ask me) deny the math, when in all other cases, the math is king, undeniable!

5. In math, the most basic theoretical math, I CAN have a negative amount of something. ( I HAVE 10 apples, but you take 15 apples from me, leaving me with -5 apples). The math is perfect and wrong! At no point do I EVER HAVE -5 apples. I have zero and you were not able to take more than 10.

Two (or more) theories can speculate on the same thing, use the same experimentation and since it is the same experiment, receive the same outcome. This outcome, then, does not even actually tell which theory was correct!

You know Larry you should stop by and see some of the newest comments and thoughts on the hub.

Yeah Larry I would also like your "help/input" on a part of my theory that I cannot seem to find the right piece to fit into the puzzle. I know you are familiar with theory, and no one has noticed this error and pointed it out, but I did. And just can't rest till I figure it out. Thanks hun!

Hi guys--

So I just found this and I can see it's been about seven months, and I have a decent vocabulary but some of the terms and linkages here confuse me and I'd like a bit of clarification.

"Suppose that you pan for gold as a hobby, and that you keep a nugget in a small vial inside your refrigerator. Take it out and measure the mass on a laboratory balance. Then set it out in your backyard in the Summer sun for an hour. It will acquire some heat energy. If you measure the mass again, Einstein's famous equation predicts that the mass will increase by a small amount."

"Our thrilling experiment shows that a magnetic field can store energy. The theory of Relativity predicts that the energy stored in this magnetic field has a mass equivalent."

The part I don't understand is the jump to saying gravity is equivalent to magnetism. By increasing something's energy (the gold-nugget example using heat, the experiment using electromagnetism), you minutely increase its mass, which minutely increases its gravity. As near as I can work out, this experiment only proves that magnetism and gravity are interrelated via mass, not that they are each other.

Does giving an object a magnetic pull make it fall significantly faster--moreso than the slight increase in mass the energy gained from charging it? I can charge a nail and make metal things move toward it--shouldn't that mean that its magnetic field would also make it fall to earth as fast as it pulls things toward itself plus whatever gravity does to it?

Again, I'm not an expert and may be totally wrong here but I'm just confused as to how you arrived at your conclusions.

Thanks!

Aha, I just came back and reread this when it wasn't ungodly-o-'clock in the morning and found the central assertion at the beginning where you reframed the question into "is magnetism equivalent to mass". I see some of where my confusion happened now, since I missed that part the first time!

Thanks very much for your kind remarks, they mean a lot to me. I was looking into this discussion for my science-fiction story--there's a ship that uses a spinning pressurized-iron core to generate a magnetic field, much like a planet does, for purposes of radiation shielding. I had heard in passing of the gravitation-magnetism similarities before so I wanted to see how well they fit together to see if maybe the core would also be good at generating a sort of artificial gravity other than making the floors magnetic. I'm thinking now I may just use spin-gravity like in Interstellar. Thanks for all your help!

54