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blog.robertelder.org
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Well I guess we can all have a good time every once in a while. Some similarly well-veiled nuggets of wisdom from my EE 101 prof – with apologies in case I misremember them but it’s the first time I’ve written them down, and it was a long time ago, so…

Please be warned these are basically engineer dad jokes, which is why I’ve also added some background info for some of them, they are a little obscure. They are, objectively speaking, extremely bad, so bad they’re good, basically.

On the state of electrification (long story short, this is how our EE 101 course began, it’s a long tradition, and our prof liked to put a spin on it from time to time because he’d taught it for decades). From the most ancient of times, people have observed that certain objects, such as rods of bakelite or pieces of amber, upon being rubbed against a cat, can attract or repel other tiny objects. Some of the more curious people attempted to replicate some experiments in detail, and verified this property using, for instance, pieces of bakelite of all shapes and sizes, and various cats. In time, they determined that this property of attracting or repelling certain other objects does not depend on either the shape of the object, or that of the cat, and they concluded that this must be a property of the material.

(Needs no explanation, it’s just cats are cute and it all sounds kindda cute?).

On the existence of magnetic charges. Some scientists have attempted to salvage the “magnetic charge” through various theoretical means. For example, they’ve attempted to come up with ergodic models of magnetic field lines, which would reconcile the existence of magnetic monopoles with that of closed magnetic field lines. Some of these models are interesting and are worth pondering but as engineers it is important to remember that fancy math is much better at holding theorems together than at keeping electrical machines together.

(Background: for a long time, people thought there ought to be some kind of magnetic charge analogous to electric charge – i.e. individual “north” and “south” charges, just like there are individual positive and negative electrical charges. This has turned out not to be the case but that hasn’t stopped mathematically-inclined physicists from attempting to salvage it, with interesting but – as far as I know, maybe something’s changed in the last 15 years or so? – experimentally futile results. However, some of these models are interesting in that, armed only with math, it’s extraordinarily difficult to figure out what incorrect assumption they make, or where they’re wrong. They look extraordinarily tempting, were it not for the damn experiments.)

On Maxwell’s field equations when moving at relativistic speeds. I am only going to explain this briefly because it exposes some of the limits of the Maxwell-Hertz model, but if you ever find yourself needing these for reasons other than curiosity, you probably missed a decimal point somewhere.

(Background: engineering sophomores sometimes end up with e.g. rotors turning at what amounts to linear velocities of hundreds of thousands of kilometers/sec but are too focused on crunching the numbers to notice that’s physically impossible)

On magnetic permeability of vacuum. The magnetic permeability of vacuum is \mu_0 4π×10−7 H/m, or approximately 1.25 ×10−6 H/m. Please don’t sweat it, you’ll know this by heart by your fourth year, in the meantime you can just asks me if you forget it. I promise I’ll give you the right values, I’ve only played a cruel joke on one of my students who sheepishly asked me what the value of \mu is. I was pretty confused because it was not a field problem, it was in a Circuit Theory seminar, until I realized he was asking me about the \mu in \mu C (i.e. microcoulombs). I told him it’s 10^-6 and he asked me if I was sure, because he remembered there was something else with 4π times something – I said no, young man, you’re thinking of \mu_0, that’s a whole other thing. He was very happy, I just couldn’t spoil the surprise until after the test.

(Background: oh boy. Okay, so one microcoulomb is 10^-6 coulombs. The student was clueless as in, he had no idea the \mu in uC has nothing to do with the \mu in EM field equations, which is the magnetic permeability of a material, and it just so happens to be denoted by the letter \mu. \mu_0 is a particularly important value, the magnetic permeability of vacuum, because the magnetic permeability of other materials is often expressed relative to this particular value, as it makes a bunch of math easier).

About the importance of theory and fundamentals. Some people classify electrical and electronic applications based on “how strong” the currents are. It is certainly true that some branches of electrical engineering deal almost exclusively in either very strong or very weak currents, and I must caution you against truisms like “the physics is the same” – it is, but the engineering of an electric arc furnace is very different from that of an integrated circuit. That being said, I have had students who were successful in both. For example, one of them worked on one of the first CPUs with more than 1M transistors, even though his bachelor’s, and I think even his PhD, was supposedly in one of the “strong currents” branches. So you can clearly be proficient at both. In fact, judging by how much that CPU heated, I suspect he was often proficient at both, like, simultaneously.

(Background: oh ffs. Okay so actually a lot of the physics, especially heat-related and things like insulation physics, are extraordinarily similar at radically distant branches of electrical engineerings. Heat dissipation is a problem at both ends. Sometimes it’s hard to tell if an IC is heating up like crazy because that’s just how it’s supposed to heat up (anyone remember Cyrix CPUs?) or because it’s damaged and it’s seconds away from letting magic smoke out – which is often seen in the form of drawing extreme amounts of current).

About the importance of rigorous use of technical and scientific terms. It’s important to be precise not because it’s a matter of pedantry, but as a matter of prudence. Being ridiculed by your peers is the best that can happen, actually. You never know when you end up using the wrong word in a way that makes sense to your coworkers and you only realize it upon seeing the prototype.

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And why is this great writeup not a blog post rather than a comment that will soon wash away like a castle in the surf?

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Just as with most ’off the cuff’ replies from Chisnall et al. it would be foolish not to have a scraper running at all times on x64k for later recollection. The best parts of the Internet has always been in this semi-ephemeral form, blogs invite too much review and self-doubt. Build your own repo of breadcrumb brilliance.

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The best parts of the Internet has always been in this semi-ephemeral form

That’s exactly why I love forums! Social news aggregators like the orange site, which restrict discussion around things someone else has written somewhere else, have reduced much of the discussions on Internet forums to peanut gallery status, since all the discussion is basically talk about stuff someone else has written somewhere else, often a long time ago. But it doesn’t have to be like that. I’d much rather post something cool in a community I like – where it can spark some real discussion, and occasionally even some laughter – than throw it off on a blog. It’s sort of the Internet life equivalent of telling a good story to the people you go out for drinks with.

(FWIW I think we’re not immune to this peanut gallery effect here on lobste.rs either, I think it’s just somewhat less prevalent because of the invite system and the insistence on technical subjects. That kindda brings out the good “off the cuff” replies like @david_chisnall’s, which I’m also always on the lookout for).

As for a blog, it does indeed invite too much review and self-doubt! I do have one, on which I haven’t posted in like forever, mostly because while I enjoy write-ups like these, I keep questioning the wisdom of posting them. Is it technical enough so that it’s worth reading as opposed to, you know, just “content”? Specifically for the write-up above, is it factually accurate, or would I be doing my prof a disservice by misquoting him? I mean it’s been fifteen years since I took that course. I’m not really an EE anymore, whereas he may still be teaching (pretty sure he’s long retired now but invited speakers are a thing). I really don’t trust the Internet well ackshually machine to put my prof’s light-hearted fun at magnetic monopoles in its proper context (seriously, stern defenders of magnetic monopole models within the framework of classical electromagnetism (quantum mechanics and condensed-matter systems are a whole other things) are like the flat earthers of the EM world). I guess some things are just best kept for a more select audience :-P.

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This reminds me very much of a very early web page (like 1996 or so) called something like “How to Install an HP laser printer as told through interpretive dance” and just had photos of some dude making silly poses while he installed the printer.

Every now and again I’ll try to find that page on the Wayback Machine but I haven’t found it yet.

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I’m on a hunt for a satirical video where someone (I vaguely remember the name Eric/Erik) claims to offer a way to speed up your internet connection using tinfoil or something. It had that quintessential early 2000s music and feel along with it, and was produced with a modicum of quality.

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Everybody print a copy of that right now and stash it in your bunker, so after the apocalypse we can all make 6502 CPUs with bespoke CP/M-based operating systems to run our Gemini servers on.

The real chemicals are usually hazardous and you should only work with them with proper safety gear

True story: Caltech had (at least in the 80s) a freshman-level lab class, APh9, where you make your own semiconductors and transistors. I didn’t take it, being more a software guy even then, but I heard from reliable peers my frosh year that one of our class had held a wafer in their rubber-gloved hand while pouring hydrofluoric acid onto it, causing the TA to go into panic mode. I do not recall whether the acid actually got on, let alone through, the glove. HF is one of the worst things you can possibly get on your skin; apparently it doesn’t create showy obvious burns, but steadily eats through flesh until reaching bone, and is difficult to neutralize. I do know the student wasn’t hurt, but I hope they were talked into dropping the class (and maybe switching to a more theoretical-physics track.)