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Intuitive Guide to Maxwell's Equations

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31–40 of 95 posts

Re: Intuitive Guide to Maxwell's Equations

#31
post #9

Earlier quoted context omitted.

Geometric algebra is a bit awkward notationally. Physicist prefer to use an alternative notation based on exterior calculus that does provide a compact representation of Maxwell equations: d F=J dF=0 Geometric algebra produces two equations too, by the way, not one.

You can even write them in terms of the four-vector A rather than F (related by F = dA) to reduce them to d dA = J.

escape your hodge duals fam

Re: Intuitive Guide to Maxwell's Equations

#32
post #7

These kinds of visual, well thought out explanations of topics which are often taught with terse, obscure and uninviting methods are a gift. On a tangent: I remember asking my Calculus 101 professor what the "intuitive meaning" of divergence and curl was, outside of the formal math and equations. He was shocked that one could ask to sully these perfect mathematical concepts with dirty intuitive reductions. A guide li…

Wikipedia is probably the most obvious modern exemplar of this. The editors of most mathematics articles clearly are much fonder of playing with the equations editor than they are of actually explaining things.

The thing is that writing an intuitive explanation is hard, while writing down the actual definition is easy. Also, one person's intuition is frequently another person's gibberish (hence the "monads are like a burrito" phenomenon).

Re: Intuitive Guide to Maxwell's Equations

#33

These kinds of visual, well thought out explanations of topics which are often taught with terse, obscure and uninviting methods are a gift. On a tangent: I remember asking my Calculus 101 professor what the "intuitive meaning" of divergence and curl was, outside of the formal math and equations. He was shocked that one could ask to sully these perfect mathematical concepts with dirty intuitive reductions. A guide li…

The book Geometrical Vectors does exactly that. In fact, it considers the gradient vector to be a different kind of vector than a normal distance vector. If I have a vector between two points, and I compress space so that the points move closer together, then the distance vector gets smaller. However, the gradient vector gets bigger. The gradient is basically a density, it's units are units-of-whatever-your-taking-th…

Can you mention the name of the authours..

Re: Intuitive Guide to Maxwell's Equations

#34

These kinds of visual, well thought out explanations of topics which are often taught with terse, obscure and uninviting methods are a gift. On a tangent: I remember asking my Calculus 101 professor what the "intuitive meaning" of divergence and curl was, outside of the formal math and equations. He was shocked that one could ask to sully these perfect mathematical concepts with dirty intuitive reductions. A guide li…

just a quibble, if your Calculus 101 covers div and curl, you are going to an intense STEM school and really could be expected to understand the math.

Re: Intuitive Guide to Maxwell's Equations

#35
post #9

Earlier quoted context omitted.

Geometric algebra is a bit awkward notationally. Physicist prefer to use an alternative notation based on exterior calculus that does provide a compact representation of Maxwell equations: d F=J dF=0 Geometric algebra produces two equations too, by the way, not one.

You can even write them in terms of the four-vector A rather than F (related by F = dA) to reduce them to d dA = J.

Discovering that the Maxwell equations can be written in this succinct form is kind of mind-blowing, but I'm wondering whether it provides any additional insight? It seems like one needs to do a significant "unpacking" to actually use the equation or gain insight from it. I would love to hear an explanation of electrodynamics starting with "star ddA = J".

Re: Intuitive Guide to Maxwell's Equations

#36

These kinds of visual, well thought out explanations of topics which are often taught with terse, obscure and uninviting methods are a gift. On a tangent: I remember asking my Calculus 101 professor what the "intuitive meaning" of divergence and curl was, outside of the formal math and equations. He was shocked that one could ask to sully these perfect mathematical concepts with dirty intuitive reductions. A guide li…

The book Geometrical Vectors does exactly that. In fact, it considers the gradient vector to be a different kind of vector than a normal distance vector. If I have a vector between two points, and I compress space so that the points move closer together, then the distance vector gets smaller. However, the gradient vector gets bigger. The gradient is basically a density, it's units are units-of-whatever-your-taking-th…

I'm not personally knowledgeable enough to suggest how this would behave in geometric algebra, I'm just smart enough to think that this would behave much cleaner in that framework.

Would really like to have that free time to delve and be able to suggest the alternative formulation myself.

Re: Intuitive Guide to Maxwell's Equations

#38
post #20
post #19

Earlier quoted context omitted.

Probably true! That said, Wikipedia's mathy pages have proved repeatedly useful to me as a reference, e.g., whenever I remember a mathematical concept only vaguely or intuitively and just need to find a detailed formalization to implement it in code. My browser is always open, so Wikipedia is often the "reference of least resistance."

I'm at least ambivalent about a general purpose encyclopedia having whole categories of articles that are mostly only accessible to specialists. In an ideal world, there would probably be a companion "Mathepedia" or something along those lines with a different target audience. But, of course, Wikipedia doesn't really have the concept of a specific reader persona like a conventionally edited reference does.

I'm ambivalent too, i.e., I agree with your original comment but also, personally, frequently find Wikipedia's "general purpose encyclopedia for specialists" useful.

FWIW, there's Simple Wikipedia (https://simple.wikipedia.org), but it is, quite frankly, terrible for learning about anything of a mathematical nature beyond high-school algebra.

Perhaps Wikipedia should add a "Learn About This" section to math, physics, engineering, and hard-science pages?

Re: Intuitive Guide to Maxwell's Equations

#39
Unrelated to the subject, but while viewing the pdf in the GitHub viewer using Firefox on Android: halfway through Firefox crashed and my phone's wallpaper changed. Strange bug, and I can recreate it. Anyone else?

Re: Intuitive Guide to Maxwell's Equations

#40
post #28
post #7

Earlier quoted context omitted.

Wikipedia is probably the most obvious modern exemplar of this. The editors of most mathematics articles clearly are much fonder of playing with the equations editor than they are of actually explaining things.

Well, it's not Wikipedia's fault if people producing intuitive content are not contributing to it. It's not like editors go out of their way to remove nice explanations.

There are many anecdotal reports of tyrannical Wikipedia editors doing exactly this. They claim dominion over a subset of Wikipedia articles and then manicure them exactly to their own personal tastes. I'm sure the situation you describe happens often in various corners of the website.
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