Archive for Maxwell’s Equations

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Posted in Biographical, Education, Maynooth, The Universe and Stuff with tags , , , on February 1, 2022 by telescoper

So today I gave my first lecture of the new Semester, it being a gentle reintroduction to Maxwell’s equations for a 4th-year class on Advanced Electromagnetism. They have seen these equations before but it doesn’t do any harm to spend a bit of time refreshing the memory. In what follows I do some potential theory, applications to electrostatics (method of images, multipole expansions, use of the complex potential, etc), dielectric materials and polarization, magnetostatics, relativistic formalism of electromagnetism, gauge invariance, electromagnetic radiation and energy transport, and (if time) plasma physics (if time).

When I taught this module last year I did it all remotely from home – using the blackboard shown above – but this year until further notice I’ll be doing it in person in an actual lecture theatre, though I will be recording the lectures in case any students wish to look at them again for revision, etc, and webcasting them for any students unable to attend on campus. I know there are differences of opinion on this, but I think recording of lectures should become routine practice – as it is in all UK universities I’m aware of – but that is difficult here in Maynooth because the equipment available is inadequate (by which I mean virtually non-existent). Let’s hope the necessary investment will be made at some point.

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The Terror of Maths

Posted in History, The Universe and Stuff with tags , , , , on May 9, 2016 by telescoper

I’m not sure whether to be amused or appalled by the story of the Professor whose flight was delayed in order for him to be interrogated because a fellow passenger saw him doing some mathematical calculations. I know some people who find mathematics scary but that’s taking things too far! I wonder if the passenger was Simon Jenkins?

I was wondering whether the calculation was concerned with plane geometry but that seems not to be the case. The academic concerned is an Economist and he was studying a differential equation. That surprises me. I hadn’t realised economists knew about calculus. Or about anything else, for that matter.

The BBC coverage of the story used the following image:

scary_maths

The physicists among you will recognize this as a representation of some of Maxwell’s Equations. I very much doubt they played a part in the work of  our Economics Professor, so presumably this is just one of the  BBC’s stock of generic “scary maths” images.

Other things worth noting are that this version of Maxwell’s Equations isn’t written in SI units, the standard notation in the UK and Europe. As a matter of fact it uses cgs units, which suggests it may be an American import. Nor is it really correct anyway, because the time derivative inside the brackets should surely be partial.

All of which goes to demonstrate how Mathematics is usually viewed in the media and, by extension, the public at large: like an arcane book written in an incomprehensible  language that should be viewed with suspicion or ridicule by any sensible person.

There is nothing new about this, of course. I’m reminded that in 1870, during the Franco-Prussian Way, Norwegian mathematician Sophus Lie was arrested in France on suspicion of being a German spy because the authorities thought his mathematical notes were coded messages of some sort.

In reality, mathematics is the most open and universal language of all and, as such, is a powerful force for human good. Among many other things, quantitative reasoning and proper logic help to defend us against those who lie and distort the facts in order to gain power. Mathematics may not be the easiest language to learn, but it’s well worth the effort, even if you can only master the basics.

 

 

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A New Theory of Electromagnetism?

Posted in Cute Problems, Education, The Universe and Stuff with tags , , on September 19, 2013 by telescoper

I was delighted to see an article by Alok Jha in the Observer on Sunday discussing Maxwell’s Equations, but my rapture was rapidly modified when I saw the image that accompanied the piece:

Maxwell's Equations

Since our new students are just settling into their courses in the Department of Physics & Astronomy here at the University of Sussex, I thought it would be fun to post this here and invite my readers (some of whom are students) to spot the deliberate mistake(s). More amusingly, how about offering suggestions as to what the Universe would be like if electromagnetism did indeed behave the way described by the alternative theory outlined in the Observer article.

Answers through the comment box please!

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