Do we understand electromagnetics?

[jonourd]

Electromagnetics has become integral to the existence of the Modern world, we cannot function without man-made electrical power or natural electromagnetic energy but do we really undersatnd it?

 

[Dale]

Welcome to PF!

Yes. IMO, the most important and clear test of whether or not you understand a physical principle is if you can build something useful using that principle. If you don't understand, or if your understanding is wrong, the device won't work. However, I am an engineer, so I may have a rather biased view.

 

[jonourd]

What is the difference between natural electromagnetic energy and man made or is there a difference?

 

[Dale]

There is none, other than the fact that man made sources are typically much more steady and regulated.

 

[jonourd]

And with respect to the develoment of Radio as we know it, radio on our kitchen tables that is, did commercial interest prevent this area of electromagentic development from going further, into let's say more obscure areas.

 

[Danger]

Radio itself has come an incredibly long way since it was first discovered, up to the current level of our technological ability.
Remember that radio waves are simply a section of the EM spectrum, so things like microwave transmitters (and ovens) can be considered radio developments.

 

[chroot]

We can build everything from particle accelerators to communications lasers to nano-scale microcircuits using our existing theory of electromagnetics. We understand solar winds and stellar spectra using it. We have successfully applied the theory to systems dozens of orders of magnitude different in size and power. I'd say... we understand it. In fact, of the four fundamental physical forces, the electromagnetic force is probably the only one we really understand thoroughly.

- Warren

 

[chroot]

As far as radio is concerned, commercial interests are what drive progress. We have communications satellites broadcasting gigabytes of digital data every second through advanced modulations and error-correcting mechanisms. We have $100 cell phones with spread-spectrum frequency-hopping digital communications done in a single chip. We have software radios. We have the Global Positioning System, which basically uses the properties of radio waves to pinpoint a location on the Earth's surface with sub-millimeter accuracy. We have elaborate radio telescopes, hundreds of feet across, which are effectively large radio receivers. Radio has come a hell of a long way since the days of Marconi... and almost all of the advances have been in the interest of either commerce or military.

- Warren

 

[wysard]

As far as radio is concerned, commercial interests are what drive progress. We have communications satellites broadcasting gigabytes of digital data every second through advanced modulations and error-correcting mechanisms. We have $100 cell phones with spread-spectrum frequency-hopping digital communications done in a single chip. We have software radios. We have the Global Positioning System, which basically uses the properties of radio waves to pinpoint a location on the Earth's surface with sub-millimeter accuracy. We have elaborate radio telescopes, hundreds of feet across, which are effectively large radio receivers. Radio has come a hell of a long way since the days of Marconi... and almost all of the advances have been in the interest of either commerce or military.

- Warren

Beautifully worded. Right up to the bit about Marconi. ~sigh~ Faraday invented Radio. Even patented it. Marconi tried sucessively to steal it in repeated bogus patent claims until one slipped through. Took poor Faraday into the late 1960's to get it reversed. And forty years later they still teach that an unlettered grifter with his one eye on the door and the other to the main chance can be just as brilliant as all the respected scientists in the world as long as he is born a US citizen. It is to laugh, to weep, and perhaps drive some young men postal...lol

 

[jonourd]

Who in invented radio is arguable and its an old one and will be bashed out for years to come, George Francis Fitzgerald and Hertz are wonderful pioneers, I have often wonder what if they and Maxwell went another direction, where would we be? Assuming they did go another direction can any of you imagine where that might be and what might have happened?

 

[ZapperZ]

Who in invented radio is arguable and its an old one and will be bashed out for years to come, George Francis Fitzgerald and Hertz are wonderful pioneers, I have often wonder what if they and Maxwell went another direction, where would we be? Assuming they did go another direction can any of you imagine where that might be and what might have happened?

You are going somewhere with this whole thing. I don't know where yet, but I don't see any physics content in this, or else Maxwell equations would have been featured prominently in why you don't think these are satisfactory in understanding electromagnetism.

Since this is more of a "historical" issue and not physics, I'm moving this to the GD forum.

Zz.

 

[russ_watters]

I have often wonder what if they and Maxwell went another direction, where would we be? Assuming they did go another direction can any of you imagine where that might be and what might have happened?

We'd be right where we are today. Radio was an invention - radio waves are not.

 

[jonourd]

You are going somewhere with this whole thing. I don't know where yet, but I don't see any physics content in this, or else Maxwell equations would have been featured prominently in why you don't think these are satisfactory in understanding electromagnetism.

Since this is more of a "historical" issue and not physics, I'm moving this to the GD forum.

Zz.

I can see your point of moving the post to a degree, I suppose I want to lead the discussion into a creative platform technically if you wish to move the post there because you feel creativity is not part of physics then do so but if not think about it and then anser accordingly, apologies if that sounds snotty it is not meant to be, maybe we should start a new thread entitled can theoretical technicians incorporate imagination and creativity into their conversation but I would prefer for the thread to remain where it is and have people engage with it as so.

 

[chroot]

jonourd,

We decide where posts go. You should also recognize that ZapperZ is a professional physicist, and knows quite well the role of creativity in science.

- Warren

 

[waht]

Electromagnetics has become integral to the existence of the Modern world, we cannot function without man-made electrical power or natural electromagnetic energy but do we really undersatnd it?

We only have elaborate models of how electromagnetic waves might behave. But truly, no one knows what it is. Just like in models of atoms, electrons are orbiting the nucleus, in quantum mechanics models call for electron clouds to describe atoms, which is amazingly accurate. In the untested yet string theory, particles are modeled to be vibrating strings of energy. Sounds great, but still we have no idea what everything is at the most fundamental level.

 

[russ_watters]

I have often wonder what if they and Maxwell went another direction, where would we be? Assuming they did go another direction can any of you imagine where that might be and what might have happened?

I guess I'll take a stab at this: Are you suggesting that if people's creativity had led them in different directions, Maxwell's equations would look different than they do now?

 

[Donski]

Simply because we have theories that can predict the outcomes of electromagnets for an extreme degree, does this really mean that we fully understand it?

In my electronics class I learned about the right hand rule. I have no problems with it and I know how to apply it. What bothers me is that we even have a right hand rule. If we lived in a mirror universe then couldn't it be a left hand rule. Why can't it work equally well in both directions? I don't think anyone can actually answer the question why, all they do is show evidence to prove that it is. I've learned to accept the fact and live with it.

But still, how can something work well in one direction but not equally well in the other?

 

[Gokul43201]

But still, how can something work well in one direction but not equally well in the other?

I think it might help to learn what an axial vector (or pseudovector) is.

http://mathworld.wolfram.com/Pseudovector.html

 

[Astronuc]

In my electronics class I learned about the right hand rule. I have no problems with it and I know how to apply it. What bothers me is that we even have a right hand rule. If we lived in a mirror universe then couldn't it be a left hand rule. Why can't it work equally well in both directions? I don't think anyone can actually answer the question why, all they do is show evidence to prove that it is. I've learned to accept the fact and live with it.

The reference orientation and nomenclature are arbitrary, but the relationships involved at what they are. We look at natural process and try to describe them as best we can. The fact that we can predict reasonable well outcomes of experiments, and we can manipulate materials to build generators, motors, lasers, CPU's and other microelectronics, lights, radar, microwave ovens, . . . . indicates that we understand EM pretty well.

The RHR or LHR reflect something of the duality of nature. In a Cartesian coordinate system, on any of the three principle and orthogonal directions, one either goes forward or backward (reverse) - two choices. In rotation in a plane (2D) - one either goes clockwise or counterclockwise - there is no third choice.

But still, how can something work well in one direction but not equally well in the other?

Please provide an example.

 

[Donski]

Examples are all around us, and I think you're reading far more into it than needed. If you took a textbook explaining the right hand rule and changed every place that said "right hand" to "left hand", and every place that said "left hand" to "right hand", it wouldn't work the same. The fact that the rule only works in one direction allows us to build DC motors and have them rotate in the desired direction every time. Simply because you can explain the cause of the right hand rule in great detail still doesn't negate the fact that it rotates in only one direction perpendicular to the flow of electrons through a wire. Passing the blame to something else that spins in only one direction at a subatomic level still doesn't answer my question. So then I'm just left asking, why would that only spin in one direction and not the other? It just goes on and on and on. It's as if God flipped a coin and said "I think I'll have it work this way".


And I really don't care because we made some cool toys with it. ;)

 

[Astronuc]

Examples are all around us, and I think you're reading far more into it than needed. If you took a textbook explaining the right hand rule and changed every place that said "right hand" to "left hand", and every place that said "left hand" to "right hand", it wouldn't work the same. The fact that the rule only works in one direction allows us to build DC motors and have them rotate in the desired direction every time.

Changing the polarity of the DC input causes a DC motor to run in the 'opposite' direction. That is how we have reversible drills and motors.

But certainly, if one changes only the nomenclature but not the physics, nothing really changes.

 

[Moonbear]

Post #5 in this thread might help:
https://www.physicsforums.com/showthread.php?p=1514802

 

[Donski]

Post #5 in this thread might help:
https://www.physicsforums.com/showthread.php?p=1514802

It doesn't help at all because it only answers the question how, and not why.
So far every time a person answers, it just proves they don't understand the question.

Now here's a post in this thread I like.

We only have elaborate models of how electromagnetic waves might behave. But truly, no one knows what it is. Just like in models of atoms, electrons are orbiting the nucleus, in quantum mechanics models call for electron clouds to describe atoms, which is amazingly accurate. In the untested yet string theory, particles are modeled to be vibrating strings of energy. Sounds great, but still we have no idea what everything is at the most fundamental level.

I give up because at this point in history we just don't have the answers yet.

 

[Gokul43201]

Physics, and all science for that matter, is only about building models that successfully describe the way nature works. Sure, if you go far enough down a chain of "why" questions, at some point the only answer admissible is "because it works." This is not even a weakness of a model, though the fewer the independent postulates needed to build a model upon, the nicer such a model feels, and typically, it has greater predictive power.

So if you ask why certain quantities tranform as certain kinds of tensors but not others, then again, the answer to that is "because it works".

 

[novaa77]

We only have elaborate models of how electromagnetic waves might behave. But truly, no one knows what it is. Just like in models of atoms, electrons are orbiting the nucleus, in quantum mechanics models call for electron clouds to describe atoms, which is amazingly accurate. In the untested yet string theory, particles are modeled to be vibrating strings of energy. Sounds great, but still we have no idea what everything is at the most fundamental level.

I agree. Our current theories describe the behaviour of electromagnetic waves, but cannot explain the true "nature" of the electromagnetic field.

 

[chroot]

I agree. Our current theories describe the behaviour of electromagnetic waves, but cannot explain the true "nature" of the electromagnetic field.

Nonsense. Our theories describe how they work, what they do, and how to use them. What deeper description can there be than an exhaustive list of all their characteristics and behaviors?

- Warren

 

[russ_watters]

Nonsense. Our theories describe how they work, what they do, and how to use them. What deeper description can there be than an exhaustive list of all their characteristics and behaviors?

- Warren

Well, in order to understand electromagnetics, we must learn to feel things from the magnet's perspective! Empathy, warren, is the key to understanding. :tongue:

[edit] On the other hand, I may be confusing magnets with terrorists.

 

[Donski]

Well, in order to understand electromagnetics, we must learn to feel things from the magnet's perspective! :tongue:

That's a pretty attractive way to look at it.

 

[novaa77]

Nonsense. Our theories describe how they work, what they do, and how to use them. What deeper description can there be than an exhaustive list of all their characteristics and behaviors?

- Warren

Yes, but none of these tell us what the electromagnetic field actually is

For example if I were to describe the dimensions and other physical characteristics of an airplane to some one it still wouldn't give him any idea as to what keeps it up in the air.

 

[chroot]

For example if I were to describe the dimensions and other physical characteristics of an airplane to some one it still wouldn't give him any idea as to what keeps it up in the air.

So you're telling me a man cannot understand an airplane unless he has seem or experienced one? How did the first airplane come into existence, then?

My point this: What can you possibly say to another human being about what an airplane 'is' other than a list of its physical characteristics, behaviors, and uses?

- Warren

 

[jonourd]

jonourd,

We decide where posts go. You should also recognize that ZapperZ is a professional physicist, and knows quite well the role of creativity in science.

- Warren

I understand your point and I am not questioning ZapperZ's professional or technical authority , I am not sure why you have pointed that out. What I feel though is that imagination is fundamentally as important technically as technical understanding itself and therefore I feel strongly that this thread remains where it is and that people take into account the role imagination has to play in the development of Physics.

 

[jonourd]

I guess I'll take a stab at this: Are you suggesting that if people's creativity had led them in different directions, Maxwell's equations would look different than they do now?

Yes! And if business structures were not applies to the development of radio as they were we may have a very different understanding of radio and use of radio today.

 

[jonourd]

Simply because we have theories that can predict the outcomes of electromagnets for an extreme degree, does this really mean that we fully understand it?

In my electronics class I learned about the right hand rule. I have no problems with it and I know how to apply it. What bothers me is that we even have a right hand rule. If we lived in a mirror universe then couldn't it be a left hand rule. Why can't it work equally well in both directions? I don't think anyone can actually answer the question why, all they do is show evidence to prove that it is. I've learned to accept the fact and live with it.

But still, how can something work well in one direction but not equally well in the other?

Or is their evidence that those directions and scientific tangents have been explored, given of course the ideas of which no one knows were conceived of to be exprimented with in the first place?

 

[jonourd]

Examples are all around us, and I think you're reading far more into it than needed. If you took a textbook explaining the right hand rule and changed every place that said "right hand" to "left hand", and every place that said "left hand" to "right hand", it wouldn't work the same. The fact that the rule only works in one direction allows us to build DC motors and have them rotate in the desired direction every time. Simply because you can explain the cause of the right hand rule in great detail still doesn't negate the fact that it rotates in only one direction perpendicular to the flow of electrons through a wire. Passing the blame to something else that spins in only one direction at a subatomic level still doesn't answer my question. So then I'm just left asking, why would that only spin in one direction and not the other? It just goes on and on and on. It's as if God flipped a coin and said "I think I'll have it work this way".


And I really don't care because we made some cool toys with it. ;)

I feel I have been spoken for, thank you! But please continue and my fullest apologies for it being problematic.

 

[dst]

So you're telling me a man cannot understand an airplane unless he has seem or experienced one? How did the first airplane come into existence, then?

My point this: What can you possibly say to another human being about what an airplane 'is' other than a list of its physical characteristics, behaviors, and uses?

- Warren

I think what he means is what "stuff" a magnetic field is made of. Instead of saying "that particle has a force on it equal to x", he would want "that particle is made of cheese."

In this case, wouldn't such a field simply be a disturbance/change in energy spread over an area? Then you would get to "energy". What "stuff" is energy made of? :D