Rafting the great Zambezi

Eight rafts, 23 rapids, 18 kilometres of the great Zambezi river. Two unplanned swims, one raft flip, about seven grade five rapids. Altogether, one hell of a day.

My brother and I spent Wednesday white water rafting. After the briefing and breakfast, the approximately 50 of us in today’s group head down to the river. Most of the rest of the people are here on wilderness group tours — travelling in a touring truck, camping at sites along the way. It’s the usual mix of backpackers — Australia, England, South Africa, a few from American and Germany.

The route starts within sight of the base of the Victoria Falls, with the Mist that Thunders hanging over the top of the gorge walls — all 700 feet of sheer rock. We spent the rest of the day in the gorge, with the Zambezi running swift and deep between towering cliffs, and the (very welcome) sun high overhead.
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Asymmetries in scientific fields

I’ve just finished reading Michelle’s candidacy report, on some of the research she’s been doing into catalysts for certain reactions in organic chemistry. It’s highlighted for me some of the differences between different fields of research — and in particular, between theoretical physics, and the more experimental work that most other people at Caltech do.

Michelle’s report was very easy to read. That’s partially because it’s well written, but I’d say it’s also because the difficulty is in a different place to that of papers that I’m used to reading. “Reading” a longish string theory paper can take literally months — and even then, I can’t claim to understand everything that is being said. Reading Michelle’s report took a few hours, and while I didn’t understand all the jargon, I think I got the gist of the issues and approach that her research took.

On the other hand, having read Michelle’s report has brought me no nearer to actually being able to synthesise anything more interesting than a bowl of pasta and sauce. “Reading” the string theory paper, however, has involved working through the mathematics behind each step, at great length — sometimes hours for a single line. So once I’m finished, I’ve done a substantial portion of the work that was required to write the paper in the first place. The analogy would be me reading Michelle’s paper, and then making some of the reagents too — and that would take months too.
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Knots and different dimensions

It seems that most of the time these days, I being asked to think about things in a different number of spacial dimensions than 3 (up-down, left-right, forwards-backwards). Now, some properties follow through to additional dimensions quite easily, but I was thinking recently about one that doesn’t: knots — it’s a great example of the tricks that dimensions can play on one.

What’s a knot? Take a piece of string (an object extended in one dimension). Form a loop and feed it through the loop. The knot so formed cannot, by continuous deformation of the string, be “undone” without moving an end of the string back through the loop.

But knots only exist in three spacial dimensions.
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