Magnetism - distilling the everyday from the extraordinary

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Steve3007
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Magnetism - distilling the everyday from the extraordinary

Post by Steve3007 » May 17th, 2014, 7:37 am

When dealing with things that are far removed from everyday experience, everyday notions and words will not necessarily suffice. We have to be careful to acknowledge exactly what we're saying, both explicitly and implicitly. You may think that this is of little consequence because the far-removed situations have no noticeable effect on normal everyday experiences. But that's not necessarily true either.

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Here's an example, to make the point:

The Lorentz Transformations

Special Relativity predicts that things that are moving, and the spaces between them, become shortened in the direction of motion as measured by the things relative to which they are moving. At the normal sensible speeds with which we're familiar this effect is far too small to be measurable. So it's not susceptible to understanding by what we call "common sense" - the aggregate of years of everyday experiences. It seems weird and difficult to believe because we're wholly un-used to it happening.

Image

But, even so, it results in effects that do occur in our normal everyday lives. One such effect is magnetism.

Magnetism
The easiest way to understand this is to think of electrons travelling through a wire - an electric current. As we know from high school physics, when an electric current flows through a wire it causes a magnetic field around that wire - a magnetic force is exerted on other electric charges.

Image

This is in addition to any electrostatic forces. The underlying reason for this mysterious extra force is the Lorentz contraction. The negatively charged electrons are moving relative to the positively charged ions in the wire. So this stream of electrons contracts, very, very slightly. They get very, very slightly closer together. This slightly increases the negative charge density and results in a sort of "extra" electrostatic force, which we know as the magnetic force.

Image

Now, the drift speed of the electrons which comprise a typical electric current in a wire is very slow (a snail's pace), and the Lorentz contraction is normally only noticeable at speeds comparable to that of light. So this Relativistic contraction must be truly, truly tiny. And so it is. But the magnitude of the electrostatic force is correspondingly huge. Billions upon billions of times stronger than gravity. The reason why we don't notice this, and tend to think of gravity as dominant, is that positive and negative electric charges tend to be very finely balanced and, to a high degree of precision, cancel each other out. In any situation where this is not so, large forces are exerted whereby they quickly rearrange themselves so that it is so.

A case in point is this well-known back-of-a-beermat fact: If the difference between the electrostatic charge in your head and body were 1%, the resulting electrostatic repulsive force between the two would be enough to propel your head clean out of the solar system.

This being the case, it only takes a very tiny increase in electric charge density (number of electrons per unit length of wire) to create a measurable extra (magnetic) force.

The Combination of Extremes Resulting in the Ordinary

So, what we have here is two extreme (on human scales) phenomena that we don't normally experience directly - the huge magnitude of the electrostatic force and the tiny effect of the Lorentz contraction. Together, they combine to create a normal-sized everyday phenomenon with which we are all pretty familiar - magnetism. But it takes an appreciation of the extreme phenomena to fully understand the mechanisms for the familiar ones.

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The Question

Are readers happy to allow that familiar, everyday phenomena are explained in terms of such combinations of seemingly outlandish and initially difficult to believe underlying mechanisms? Or do you mistrust these explanations? Is it a tenet of your philosophy that it must be possible to describe everyday things using everyday mechanisms and language?

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Re: Magnetism - distilling the everyday from the extraordina

Post by Philosophy Explorer » May 21st, 2014, 6:00 pm

Steve wrote:

"...a magnetic force is exerted on other electric charges."

More accurate would be to say that a moving magnetic force creates electricity.

Still studying your OP.

PhilX

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Re: Magnetism - distilling the everyday from the extraordina

Post by Mechsmith » May 21st, 2014, 9:54 pm

I don't remember who actually said this first. Nils Bohr perhaps.

"If your theory is any good then you can explain it to a barmaid." This I believe is a comment on the basic simplicity of physics and peerhaps a snide comment as to the narrators proficiency in communications.

Basic physics is not complicated, despite the fact that we do not understand all of the ramifications of it. For instance consider our new pet called "E=Mc squared" . This simply means that if we want to convert energies to matter or vice-versa we can use this formula to give us a pretty good guess as to the result of converting matter (mass) to energy (heat and motion).

I elaborate somewhat. What does E=Mc squared actually mean? It means simply that if you smash two particles each traveling at light speed the energies released by their destruction will equal E. I disremember how to work out the equivalent units of measure. Look it up if it matters. For practical purposes a velocity of c squared can only be achieved within a concentration of matter equivalent to a giant star, or perhaps a galaxy or a universe concentrated to a point. This is one of the basises of the Big Bang Theory. Similar processes account for all elements heavier than Hydrogen. If you've a lot of energy and want to make some matter simply reverse the equation. (solve for M)

The Universe is not particularily complicated. It is what it is and it works without intelligence and pretty dependably so consequently it must be basically simple. However it is larger and smaller than we can easily understand. Throw in a little imagination and "there's the rub" :wink:

Now I am going to talk to a barmaid :D

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Re: Magnetism - distilling the everyday from the extraordina

Post by Steve3007 » May 22nd, 2014, 2:41 am

Mesmith:
"If your theory is any good then you can explain it to a barmaid." This I believe is a comment on the basic simplicity of physics and peerhaps a snide comment as to the narrators proficiency in communications.
No doubt a fair comment! I wouldn't claim to be a great communicator. But I would point out that the explanation given here is about one page long and I'd guess it takes maybe 10 minutes to read. Perhaps 100 times shorter than a typical basic introductory textbook on electricity and magnetism. Most barmaids I've known would be more than capable of understanding it! The question is, whether they'd be interested! As a rule, I've found that it's lack of interest, not lack of comprehension ability, that stops people from learning things. And that's fair enough. It's not compulsory to be interested in everything.
The Universe is not particularily complicated.
Looking around me, I'd have to disagree! You're clearly way cleverer than I am!


Phil:
More accurate would be to say that a moving magnetic force creates electricity.
Both are true. You're describing the induction of an electric current by a magnetic field - the principle on which a dynamo works. I'm describing the other way around - the principle on which a solenoid or electromagnet works.

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Re: Magnetism - distilling the everyday from the extraordina

Post by Obvious Leo » May 22nd, 2014, 3:17 am

Mechsmith wrote:"If your theory is any good then you can explain it to a barmaid."
It was Albert Einstein and the quote goes. "It should be possible to explain the universe to a barmaid". I agree with him.

Regards Leo

-- Updated May 22nd, 2014, 3:22 am to add the following --

G'day Steve. The Lorentz transformation is a mathematical representation of a process, not a mechanical explanation for it. In other words it's an action-at-a distance model which can claim no explanatory authority.

Regards Leo

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Re: Magnetism - distilling the everyday from the extraordina

Post by Steve3007 » May 22nd, 2014, 4:07 am

Hi Leo,

...and yet it is central to the laws of electromagnetism that allowed the transformer in the PC/phone that you're currently using to be designed. As we're discussing on other threads, you can possibly have debates about the aesthetics of such concepts but it's difficult to use a device which was designed using them to help you to communicate arguments against their utility.
It was Albert Einstein and the quote goes. "It should be possible to explain the universe to a barmaid". I agree with him.
It is. It just depends how much detail you want to drill down to. The top levei is :"the universe is the universe". Simplicity: high. Information content: none. From there on, you take your choice as to how far you want to go; a trade-off between simplicity and useful information. In the OP I went just a little tiny bit further down into one particular area. Much, much less than would be done in a single basic textbook on the subject.

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Re: Magnetism - distilling the everyday from the extraordina

Post by Obvious Leo » May 22nd, 2014, 4:19 am

Steve3007 wrote:Hi Leo,

...and yet it is central to the laws of electromagnetism that allowed the transformer in the PC/phone that you're currently using to be designed. As we're discussing on other threads, you can possibly have debates about the aesthetics of such concepts but it's difficult to use a device which was designed using them to help you to communicate arguments against their utility.
Quite so, mate. I don't argue against the utility of such mathematical modelling, merely against the flawed logic which some people apply to extrapolate an explanatory paradigm from such artifice. This is doing science backwards and indeed it does offend my finely tuned preference for a physics aesthetic. We Aussies can only sleep restfully of a night-time when we're satisfied that our world makes sense, preferably in words of two syllables or less.

Regards Leo

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Re: Magnetism - distilling the everyday from the extraordina

Post by Steve3007 » May 22nd, 2014, 4:25 am

This comes back to a comment I made on another thread: what is the difference between "explanation" and "description"? You clearly think that there is one, and that it is fundamental. I do not.

For sure, we can use the very useful working model known as "cause/effect" to create deeper descriptions underlying our superficial descriptions. But it's still descriptions all the way down. There is no point at which we suddenly go from description to explanation.

We could explore this with examples, but it's probably the wrong thread for it.

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Re: Magnetism - distilling the everyday from the extraordina

Post by Philosophy Explorer » May 22nd, 2014, 11:02 am

Steve said:

"We could explore this with examples, but it's probably the wrong thread for it."

I would recommend to you that setting up a new thread on this would be suitable as I think people would be interested (I know I would be).

PhilX

-- Updated May 23rd, 2014, 8:15 am to add the following --

Steve,

I think the answer is most people don't understand phenomena such as light or gravity in their deeper implications. All they want is easy explanations so that they can get on with their lives. How to make them understand is a true challenge for science.

PhilX

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Re: Magnetism - distilling the everyday from the extraordina

Post by A Poster He or I » May 27th, 2014, 6:56 pm

Hi Steve,

Your "extraordinary" explanation of magnetism has reminded me of when I first read Richard Feynman's Q.E.D. and he used quantum electrodynamics in conjunction with his sum-over-histories interpretation of quantum mechanics to explain the phenomenon of a mirage. I was blown away because his explanation was completely at odds (on the surface) with my traditional understanding (classical refraction principles).

It was years later before I realized there was no conflict at all, and that one has to be careful not to mix-and-match one's models too much, especially when one of the models lies outside the purview of common sense!

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Re: Magnetism - distilling the everyday from the extraordina

Post by Obvious Leo » May 27th, 2014, 7:52 pm

Feynman's always been a tricky genius to follow but the sum over histories is easily understood as a very close mathematical approximation to reality, not to be confused with an ontological explanation for it. Since the electron orbits its nucleus at 0.99999992 c then the wave function which describes it as being "everywhere at once" is going to be very close to the mark indeed. It's certainly close enough to allow us to make all our fancy modern gadgets but we needn't discard our common sense and assume that an electron can literally be in two places at once. It's just moving that fast that we can very accurately model it AS IF it is.

That's what quantum mechanics is, an AS IF model.

Regards Leo

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Re: Magnetism - distilling the everyday from the extraordina

Post by Mysterio448 » May 27th, 2014, 8:45 pm

Steve3007 wrote:
The Question

Are readers happy to allow that familiar, everyday phenomena are explained in terms of such combinations of seemingly outlandish and initially difficult to believe underlying mechanisms? Or do you mistrust these explanations? Is it a tenet of your philosophy that it must be possible to describe everyday things using everyday mechanisms and language?
The way I understand it, the universe as we know it is very much like the graphical user interface (GUI) used on modern computers. When you use a computer all you do is point at an icon and click and then things happen. However, this simple interface betrays an underlying complexity that the vast majority of computer users couldn't understand, things like bits and bytes and transistors and advanced calculations, etc. It's all very complicated in truth. It is interesting how there seems to be something in nature that takes wild, counterintuitive forces and condenses them into the tame, intuitive forces that we are familiar with. If you have a balloon full of helium, the inside of the balloon is filled with atoms flying around at different speeds, banging into each other and having no organized motion. However, when you look at the balloon from the outside, you just see a perfectly serene, spherical balloon. The complicated and chaotic has been condensed into the simple and orderly. Moreover, scientists of quantum mechanics say that the majority of the mass of an atomic nucleus is in a field of virtual particles called gluons. The gluons are constantly popping in and out of existence, in a manner that arguably violates the first law of thermodynamics. Yet it is upon this bizaare foundation that all matter is built. Reality as we know it is a balance between the weird and the familiar, the complicated and the simple. The world as we see it is just the interface to a much more complicated world underneath.

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Re: Magnetism - distilling the everyday from the extraordina

Post by Obvious Leo » May 27th, 2014, 9:14 pm

Quantum field theory should not be taken so literally and nowadays only the most rabid of fundamentalists talk of virtual particles popping into and out of existence as if this were a physically real phenomenon. Perhaps somebody found the first law of thermodynamics lying around in a dusty corner and decided that it might mean something, but QFT is nowadays definitely striving for an ontology of fields which doesn't include such nonsense. Personally I reckon they're barking up the wrong tree because they seek to explain the behaviour of the particles in terms of the behaviour of the fields, instead of regarding the fields as a mathematical description of the behaviour of the particles. This latter approach is the one a process philosophy would adopt but a process philosophy is incompatible with the Minkowski spacetime, since time is spatialised out of existence in this paradigm. This explains why QFT can offer predictions but no explanations, and any explanations they attempt to offer just look like crap. Maybe they look like crap because they are crap and the physicists should stop trying to play in the philosophers sandbox.

Regards Leo

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Re: Magnetism - distilling the everyday from the extraordina

Post by Steve3007 » June 3rd, 2014, 9:08 am

Poster:
Your "extraordinary" explanation of magnetism has reminded me of when I first read Richard Feynman's Q.E.D. and he used quantum electrodynamics in conjunction with his sum-over-histories interpretation of quantum mechanics to explain the phenomenon of a mirage. I was blown away because his explanation was completely at odds (on the surface) with my traditional understanding (classical refraction principles).

It was years later before I realized there was no conflict at all, and that one has to be careful not to mix-and-match one's models too much, especially when one of the models lies outside the purview of common sense!
I'm interested to understand more about why you think this is relevant to my example of the underlying mechanism of magnetism. My point there was that magnetism is a fairly common everyday phenomenon - we can experience it in a way that we would regard as relatively "direct". We're used to it. We don't see it as strange or counter-intuitive or fishy in any way. But some of the other consequences of its underlying mechanism are less common-place. I think this could be said to be true of pretty much any commonplace physical phenomenon, but I picked magnetism because I saw it as a particularly vivid example.

How would you define a model as being outside of common sense? Would it be defined in terms of the observations that are described and predicted by that model? Or is it more to do with the innate structure of the model itself? In your sum-over-histories example, I presume it would be the latter. In this case, I think it's more to do with the unnecessary complexity of the model. Like, say, using General Relativity to describe the path of a tennis ball.

To me, the chief dangers with models, as with metaphors, are in unnecessary complexity (as in your example), stretching them too far and in inappropriately mixing them. i.e. using them for purposes for which they were not designed; in situations outside of the manufacturer's recommended tolerances (as it were). But I don't see any obvious reason for avoiding mixing models based just on the commonplaceness of the observations that they describe. My argument in the OP was that this is actually essential for successfully describing and predicting many phenomena.

In the case of electromagnetism, I don't think it's possible to understand why it's called "electromagnetism" and not "electricity and magnetism" without being aware of these underlying mechanisms with their additional counter-intuitive consequences.

I don't remember having read the Feynman example that you gave, but I imagine his point there would have been to illustrate the principle of the universality of physical law; the idea that relatively complex models that were designed for describing things in more depth than we normally require for everyday life must still agree with simpler models in the limit of those everyday experiences?

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Re: Magnetism - distilling the everyday from the extraordina

Post by A Poster He or I » June 3rd, 2014, 3:25 pm

I'm interested to understand more about why you think this is relevant to my example of the underlying mechanism of magnetism.
Relevant to your magnetism example? No. I was just providing another example of your point about how an everyday phenomenon experienced in a rather direct manner (namely, a mirage) requires underlying mechanisms not intuitively understood or even recognized at all.
How would you define a model as being outside of common sense?
Classical optics is pretty common-sensical and is often the sole model provided to explain a mirage. Quantum mechanics and sum-over-histories are well beyond common sense, in this case by specifically allowing (and even requiring) superposition to explain the mirage.
I don't see any obvious reason for avoiding mixing models based just on the commonplaceness of the observations that they describe. My argument in the OP was that this is actually essential for successfully describing and predicting many phenomena.
Well, I can agree with such mixing as a sort of short-cut to understanding, perhaps. When I closely review your OP's explanation of magnetism, I find that it is coherent specifically because you quickly abandon any requirement for magnetism as a classical force, commit your explanation entirely to the metaphors of Special Relativity, then simply note that such a tiny drag created by the Lorenz transformation is felt strongly because of the strength of the electromagnetic force. A good enough layman's understanding maybe, but it carries the internal discontinuity of failing to explain why such a time-drag would manifest as magnetic energy; the discontinuity smoothed over by a quick switch back to a classical model at the end.
I don't remember having read the Feynman example that you gave, but I imagine his point there would have been to illustrate the principle of the universality of physical law; the idea that relatively complex models that were designed for describing things in more depth than we normally require for everyday life must still agree with simpler models in the limit of those everyday experiences?
Yes, as I recall Feynman was demonstrating how his QM interpretation would be consistent with classical reality. Since Feynman was not a Copenhagenist, I assume he would consider it important to eliminate any suggestion of a sharp divide between the quantum and classical worlds.

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