The 'hazing' that is Jackson: Is it necessary to understand EM?

[cmos]

In short:
Is a class based on the Jackson text necessary to truly understand electromagnetism?

In length:
I have heard many people (some on this forum) state that the Jackson text is more of an exercise in mathematical physics and/or is the “hazing” that one must endure to be a PhD in physics. So my purpose here is to gather some opinions on this matter. Does Jackson give you more insight into the fundamental physics or is it more akin to a math methods course?

The reason I ask is that I am a PhD student in electrical engineering but have a strong inclination to fundamental physics. Seeing the Jackson-based course as the de facto standard for grad level EM, I am thinking about taking the course.

Another question I have is if I possesses the mathematical maturity to take on such a course. My knowledge of “advanced” mathematics is at the level of the book by Boas. I also took undergrad electives in quantum mechanics at the level of Griffiths and classical mechanics at the level of Fowles and Cassiday (didn’t really master the later course though). My knowledge of EM was the “engineering way” using the book by Cheng.

Would the above be sufficient for undertaking Jackson? I assume first-year physicists take another advanced math methods course. Would my lack of this type of course hinder myself in a Jackson-based course?

Also, I hate to go off topic, but I would like to re-ask the questions in the previous paragraph but by replacing “Jackson” with “Goldstein.”

Thank you all in advance for your enlightening comments.

 

[ice109]

i haven't seen the problems in jackson yet nor have i tried the problems in goldstein but i suffered through a mechanics class using marion and thornton and all those problems are a hazing. they all seemed completely useless and just amounted to symbol pushing.

a friend of mine gave me some wise words about doing homework problems so i'll paraphrase. the model isn't the physics, the physics is what the model describes and the difference is subtle but important. we don't have labs at our disposal so we take these models that our forefathers have built, which we trust, and we solve "problems" using them. the model is essentially the experiment since it closely resembles the physics. this teaches the physics, the results of the "problems", not doing the problem.

in light of that i don't believe deriving an eqn or some kind of semi-analytical result for a certain circumstance from first principles is very useful. i think problems should be given such and such circumstances answer such and such questions and methods be damned. and you should be graded on how close your answers match reality.

i get the feeling that jackson will not be like this nor will any advanced book.

in fact i feel like you probably have a better intuitive understand of basic physics than most physicists considering how close you are to the phenomena.

 

[Andy Resnick]

I think you are asking part of a more general question: does receipt of a Ph.D. in Physics imply knowledge or mastery of some canon of knowledge?

That's a fairly easy question to answer for physics (i.e., yes)- although vigorous debate about what the canon should contain is legitimate and should be encouraged.

Part of the reason why the answer is so clear is becasue the amount of knowledge is small. This may sound counterintuitive, until someone looks at older fields like law and medicine, where the body of knowledge has grown to the point that no person can claim mastery of a common subset of core principles- or that whatever core principles there are, are now so far removed from the practice of the profession they are not worth learning in the first place.

 

[trinitron]

i haven't seen the problems in jackson yet nor have i tried the problems in goldstein but i suffered through a mechanics class using marion and thornton and all those problems are a hazing. they all seemed completely useless and just amounted to symbol pushing.

a friend of mine gave me some wise words about doing homework problems so i'll paraphrase. the model isn't the physics, the physics is what the model describes and the difference is subtle but important. we don't have labs at our disposal so we take these models that our forefathers have built, which we trust, and we solve "problems" using them. the model is essentially the experiment since it closely resembles the physics. this teaches the physics, the results of the "problems", not doing the problem.

in light of that i don't believe deriving an eqn or some kind of semi-analytical result for a certain circumstance from first principles is very useful. i think problems should be given such and such circumstances answer such and such questions and methods be damned. and you should be graded on how close your answers match reality.

i get the feeling that jackson will not be like this nor will any advanced book.

in fact i feel like you probably have a better intuitive understand of basic physics than most physicists considering how close you are to the phenomena.

The point of homework sets is to prepare you to do research. If you can't do basic problems you won't be able to derive a result for your next paper either. While I personally think that Jackson is a terrible book and does little to teach the underlying theory, a blanket criticism of all problem solving is beyond absurd.

 

[Vanadium 50]

I think by calling it "hazing" you are presupposing the answer.

 

[Locrian]

Jackson is valuable, and could help you understand the physics of electromagnetism much better. It could also help you in many other areas as well; I came out of the class with a much deeper understanding of orthogonal functions, differential equations, and other skills that are valuable elsewhere.

Notice my wording though: could. It's my belief that the typical graduate class setup where the teacher comes in, copies the text onto the board, and then assigns homework from the book is a waste of time. Most physics graduate professors are really awful. The man who taught my graduate E&M classes wasn't.

Still, whether you learn shouldn't depend on the teacher. What I'm saying is that many of the graduate E&M classes might be a bit absurd, and little more than a beating you take on the way to a graduate degree, but that shouldn't reflect on Jackson's text.

 

[Locrian]

i get the feeling that jackson will not be like this nor will any advanced book.

Yes, but that's just a feeling, and there's no reason to think it's particularly accurate or well informed. I found that was the big difference between my graduate and undergraduate physics - my graduate classes were applicable (and as a note, there's a great deal of flexibility in how the student can solve many of these problems). Jackson is filled with practical examples (most in the second half) and I return to it with some regularity. I will say I found my grad level solid state even more practical, but that's partly because of where my research was in.

Your post in this thread reminds me of another you made in this thread a while back:

give me a break. it can't be this hard. you guys act like jackson e&m is a herculean task.

If you felt like Marion and Thornton was hazing, then Jackson really would be a herculean task.

 

[ZapperZ]

Real world problems are not easy!. When you strip away all the simplifying conditions, you get problems in which handling it is no longer trivial.

For example, you say you can solve for the magnetic field along the axis of a circular loop of wire. But what is the field off that axis? Just because you never had to consider that when you took undergraduate E&M doesn't mean that that problem doesn't exist, or not important. When you try to solve that (as is part of the material being covered in jackson), is that "hazing", or simply an introduction to real-world problems? Is it really a waste of time to torture students to study all those different waveguide modes and geometry, or are those really used in real-world applications?

I find this rather ironic because I have now defended both sides of the wall. On one hand, we have people who are accusing that our education doesn't adequately equipped the students with things they need to be functional in the real world, and that the subject matter being taught is highly idealized that they are useless. Then we have, on the other hand, students thinking that we are simply out to get them when they are presented with more complicated situations that actually DO have a closer connection to real-world problems.

I can really understand an educator simply throwing his/her hands up in the air over this...

Zz.

 

[Crosson]

For example, you say you can solve for the magnetic field along the axis of a circular loop of wire. But what is the field off that axis? Just because you never had to consider that when you took undergraduate E&M doesn't mean that that problem doesn't exist, or not important.

If you understand the bold sentence then you understand the purpose of the calculation. Some people can understand this from their undergraduate E&M course, but some people need to personally do the more difficult calculations in Jackson to see how general the E&M theory can be.

I would say that it is worth taking a Jackson course if your conceptual understanding is not up to the level of that book, but I am not sure what the nitty-gritty of some of the calculations would be good for.

 

[ZapperZ]

I would say that it is worth taking a Jackson course if your conceptual understanding is not up to the level of that book, but I am not sure what the nitty-gritty of some of the calculations would be good for.

Plenty. For example, all those stuff on waveguides, you'd be surprised where those things come in handy. Ask any RF engineer. When one designs accelerating cavities, for example, those TEM, HEM, TE, TM etc.. modes become like a second language. Or try designing antennas.

One of the things that I'm doing right now is investigating the vacuum breakdown in high gradient structures. One can theoretically model some geometry of a protrusion in various types of RF field, for example. When one tries to do this in as a realistic of a situation as possible, you run into field equations and boundary conditions that is nowhere as ideal as what you learn in undergraduate E&M. All those Green's function method you learn out of Jackson suddenly makes sense now. Even if you model this using some finite-element package, you still have to know how to set up the field and the boundary conditions, because you have nothing resembling a clean, analytic solution.

Zz.

 

[cmos]

I definitely see the reasons for developing good problem solving skills. I'd say developing those skills while gaining a better understanding of EM complements one another very nicely. I guess what really prompted me to make this post is that I plan on taking this non-required class while many physics students become very outspoken at this very subject.

How about the level mathematics? Are the more advanced math concepts learned along the way or will most physics students have had an advanced math class before undertaking Jackson?

 

[TVP45]

I struggled with Jackson. It's a hard textbook and I had to use Lorrain and Corson as a explanatory text. I'd take the class again in a New York minute. Hard is where you learn. Faraday made a statement to the effect that if something was fun, it wasn't educational and if something was educational, it wasn't fun.

 

[TVP45]

Oh, and I thought of something that might help. When I took the e&m courses with Jackson as the text, I was a grad student in engineering physics and, because my research project was in the E school, my office/kitchen/bedroom was also. Only two of us out of that class had offices in the E school; the rest were in the Physics Dept. It was only about half way through a very difficult first semester that we learned the Physics guys had a "podunk" file of previous year's homework attmpts to use as starting points on the really hard problems . Since toolies normally didn't take the Jackson course, there was no such file cabinet in our building. The Physics guys were happy to share; we just didn't know to ask.