Awesome

[steuard]

Me: Great! I'm all ready for class: time to introduce magnetic fields and forces.

My Bored Brain: Wow, this looks dull.

Me: Look, it's the first day on a new subject, of course it's a bit dry. But there's some cool stuff in there.

MBB: Important, yes. But seriously: dull. I'm not gonna do it.

Me: We have to do it! I'm already behind what I'd aimed for on the syllabus.

MBB: Not gonna happen. Let's derive magnetism from scratch using electrostatics and relativity instead.

Me: Are you crazy? These guys are bound to be rusty on relativity; they may never have learned it well at all. And we don't have time for long digressions: I've dropped enough material as is.

MBB: Exactly! As the schedule stands, they're going to leave junior/senior E&M without ever hearing that electric and magnetic fields are secretly the same thing. I won't let that happen to any student of mine!

Me: Look, I just can't afford to... hold on... I can't afford... to bore them. How 'bout that.

Me, writing on board at start of class: "Today's plan: Screw it - we're doing something awesome."



Addendum: ukelele points out that by an awesome coincidence, today is The International Day of Awesomeness. Awesome.

Comments

[ukelele.livejournal.com]

Coincidentally, it is the international day of awesomeness! http://dayofawesomeness.com/

(Wait, it's possible for people not to know they're the same thing? I mean, after having seen them both? whoa.)

[ukelele.livejournal.com]

(also http://xkcd.com/308/ )

[steuard.livejournal.com]

Coincidentally, it is the international day of awesomeness!

Wow. What a bizarre coincidence. Awesome!

Wait, it's possible for people not to know they're the same thing? I mean, after having seen them both?

Well, if you've never studied E&M in relativity, you probably wouldn't have heard that what looks like just a magnetic field in one reference frame will actually look like a combination of electric and magnetic fields in a different frame. You'd probably have learned that the two were related and interconnected, but it's a big additional step to realize that different observers won't even agree on which one is present!

[lordhylas.livejournal.com]

Awesomeness is always good to teach. Personally, I wish that mathematics and physics weren't *so* watered-down early on. It's frustrating for me to keep finding out where there are connections and equalities where previously I'd been told there aren't, or said connections and equalities were just completely omitted. So, earlier the better, in my book.

[steuard.livejournal.com]

A project that's been very distantly on my mind for many years is to write a book with a title something like "Impatient Physics", aimed at maybe a high school level audience. The idea would be to describe the gist of as many awesome facts and interconnections in physics as possible, without spending much if any time doing the math and without getting bogged down with the necessary but less inspiring intermediate details.

Come to think of it, my philosophy for the project is inspired a bit by Feynman's QED. As I'm sure you recall, he describes quantum field theory in a vivid conceptual way, even though his readers have no chance of actually doing any real computation in the field. I would have loved an overview of physics in that style when I was a kid.

[lordhylas.livejournal.com]

Yes! QED is fabulous for people who think the way I do. Conceptual-driven teaching good!

[jon-leonard.livejournal.com]

That sounds like a fascinating book.

[pearmeson.livejournal.com]

I've had a similar idea in the back of my head for years. My working title was "Physics: The Good Parts".

QED is the most spectacular popularization I have ever seen. His bean counting metaphor of learning "what we're really doing" without needing to learn how to do it efficiently is really powerful. I used it to teach a class on science writing last year (for frosh). It was by far the most successful book I used.

[ukelele.livejournal.com]

I never studied E&M in relativity...I dunno, it just always looked like all the E stuff was the same as the M stuff except...rotated around some axis perpendicular to reality. (See also: man, should've been a physics major.)

[nemene.livejournal.com]

let see how you reac to this, I actually got mostly confused looks when I tried saying this in the Mudd Physics departmant.

I suggest that magnetic fields do not exist, magnetism does not exist. Wha we observe as magnitism is the simple fact that charged particles are effected by the electric field as observed in their own rest frame. The magnetic field is simply a mathematic artifact of this relativistic effect.

Not quite sure how to handle the whole radiation thing, being an EM wave, can it be described without the M? not sure.

[steuard.livejournal.com]

When I really think about electromagnetism, it's within a relativistic formalism based on 4-vectors (and 4-tensors). In fact, the 4-vector potential is the natural object to talk about in quantum electrodynamics, too.

From that perspective, claiming "there's no such thing as magnetism" feels a lot like claiming "there's no such thing as momentum". After all, in its own rest frame a particle's momentum is always zero! Who needs it?

So while I agree that it's possible (at least classically) to write down rules for computing electromagnetic forces on particles that never require a magnetic force to exist, those are truly terrible rules. You lose everything that makes sophisticated problem solving in physics possible, up to and including conservation of energy and momentum. And at the quantum level I don't think it's possible at all: intrinsic spin means that particles can feel magnetic forces in their own reference frames anyway.

As for radiation, I'm not as certain. You'd need to abandon all of Maxwell's equations except Gauss's law for E anyway (since the others all involve B), so conceptually there's room to simply impose the wave equation for E as an independent physical law to explain radiation. But there would be issues about frame-dependence there... still, I think you could pull it off just by defining the appropriate retarded potential. So my guess is that you'd have a working formalism, but one that felt very ad hoc and unmotivated.

[ricevermicelli.livejournal.com]

I am so glad that your bored brain scored a victory.

[steuard.livejournal.com]

One upshot of my recent frustration with a few aspects of teaching has been the conclusion that my bored brain may in fact be a better teacher than I am. It certainly has more fun. So I've been trying to take "cool but impractical" ideas more seriously.

[pmb.livejournal.com]

Some of my best lectures have been because of my "bored brain".