I was pretty well minding my own business -- it may not be pretty, but it is mine -- when the cats demanded I explain electromagnetic induction. That seemed out of character for them, given the time they spent wrestling the curved plastic rod with the ball of fluff on the end, but they were sure that's what they wanted to know. ``What makes the electricity go, and what makes it stop, and what is it doing in the middle,'' were the words of the older, grey cat, although she may have borrowed some of them from an earlier source.
``We've seen you glaring at the toothbrush,'' said the younger, white cat, who was right; I often glared at it even before it broke. It somehow drew its charge, during its working life, from a base station onto which the toothbrush was loosely placed, and I can't deny that makes me uncomfortable. It feels like the toothbrush is cheating to draw power just from being near the base. It suggests loose morals in its electromagnetic flux. ``That's why we want you to explain it.'' This, not being any kind of actual reason, convinced me of the value in replying.
I began, ``We get electromagnetic induction from the 19th century, by way of Joseph Henry, who was discovered by Michael Faraday.''
``Faraday,'' said the white cat. I nodded, and added, ``Fortunately, a far a day should be enough for any-- '' and before I could finish the approximate witticism the white cat bit me on the ankle.
I started over. ``You can think of electromagnetism as a fast-moving wave.'' The grey cat said they often did, when it didn't interfere with their professional obligations. ``So you know what it looks like when a child with a jumping rope swings the rope in big loops?'' The cats both nodded, and I knew I had caught them in a lie, because they've never been anywhere near someone with a jump rope. Whatever they were up to, they were now morally compromised. ``Imagine you have that child jumping rope.''
``The same rope?'' asked the grey cat, who tumbled on her head. I couldn't think of any ropes involved, so I just said it was the earlier one.
``Now imagine the child jumping rope,'' making the white cat ask if it was the same child as before. ``Yes, and now imagine another one with a jump rope that's nearby.'' The grey cat asked if it was the same rope, and now the question fit. ``They're not the same ropes, but they come from the same store. The children come from different hospitals,'' I added, and the white cat pretended she never intended asking. ``Now, one of the children starts jumping rope.''
``We could use some names here,'' said the white cat, so to be difficult I asked for what. ``Ballast.''
``Now,'' or later by now, ``you have one child jumping rope. This makes the other child start jumping in the same way, and that's induction.''
The cats looked skeptical. ``What makes Ballast jump? And why the same way?'' I couldn't think of any particular reason, so I suggested that maybe the ropes were tied together. ``By what, more rope?''
``It doesn't have to be rope. Maybe it's just string,'' which sounded feeble to me too, and the grey cat pressed her claws out and made no explicit threat. ``How about a Slinky? They're good waving.'' The white cat seemed to approve, and now I knew something was wrong, as she's never seen a Slinky. If she had ever seen a Slinky she would still be trapped in it. ``So it's like that, only with electromagnetic waves instead of children with jump ropes, and instead of Slinkies there's more ... waves,'' and before they could mock this I said, ``What's got you wondering about induction suddenly? You've stuck happily to traditional cat activities up until now.''
``We were hoping to figure something out,'' said the grey cat, ``and we have.'' At her disapproving glare and sense that I've been forcibly crossed off a list I went to the freezer and got ice cubes for their water dish. I probably should have said more about Nikola Tesla.
Trivia: After Arthur Cayley so well defined and gave notation for determinants of matrices (in 1841), the number of determinants for different things grew so rapidly that Sir Thomas Muir's 1920 history Of determinants ran 2,500 pages. Source: The Development of Mathematics, E T Bell.
Currently Reading: Groucho And Me, Groucho Marx.