As simple as possible, but no simpler

The title of this post is a phrase that is often ascribed to Albert Einstein. Indeed I have ascribed it, doubly-wrongly, myself in relation to modelling, without checking. I am a Bad Physicist. One of the many things I’ve learned since yesterday is that he didn’t say it. Ironically, it is probably an over-simplification of something he actually said: “It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience.” OK, maybe one-and-a-halfly wrong but let’s not get into the equivalence of modelling and theory right now.

There have been a few times in my life when I have known for a long time that there was something inherently wrong in my understanding of a subject. Yesterday, at the age of 55, I set a new record for Wrongness longevity. Despite having passed ‘O’ Level, ‘A’ Level and half a degree in physics, I confirmed my suspicion that I didn’t really understand Alternating Current electricity AC.) I’m not keen to discuss the details of how I proved this but I was relieved there was a circuit breaker.

I still wouldn’t say I really understand AC still but I have reached the point of knowing my unknown. Enlightenment may have to wait but in getting where I am, I’ve discovered there are lots of other people who don’t understand either and some of them are qualified electricians, making it very lucky for all of us that we in the UK are protected by a very well designed electrical system and ‘The Regs’ which allow people who don’t understand to navigate adequately with their one good eye, by following an explicit set of rules.

I also came across students struggling with the same misunderstandings as me, being advised by the kind of over-academic idiots that I thought were legally restricted to computing forums. If a kid is asking what “electron flow” means in an AC-circuit, s/he is probably not looking for an answer that involves quantum mechanics. But there is the problem: one of my secondary-school physics teachers, by trying to keep things as simple as possible, used an over-simplistic analogy between DC and AC current that has confused me for 40 years. Or he didn’t understand either.

To check if things had improved, I looked at current school science revision notes. If anything, they were worse. In summary: +ve and -ve don’t mean much in AC but “Live” and “Neutral” do. Current doesn’t so much “flow” as “oscilate”. Zero load is BAD. All the current! The advice not to mess with mains voltage unless you really know what you are doing also applies to me, and I was only trying to change a ceiling fan.

What I’ve learned may eventually find its way into my ‘Finds & Thinks’ book.


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