This page represents only my own views, and not those of any university or other body.
Posted Thursday 20th October 2011 at 7.12pm
What is pi?
The phrase "What is pi?" is trending on twitter. This seems to be because a girl on a TV programme called Educating Essex asked "What is pi? Where does it come from?" Most people on twitter are saying things like "That girl must be so proud... if she knows how to turn her computer on" or making jokes about pie.
I think it's a very good question for a secondary school pupil to ask. To answer, you could try to explain about real numbers as an abstract concept, and say that pi is just a particular real number; perhaps you could give the nice continued fraction expansion of pi/2 to demonstrate how you might approximate pi. Or you can go into a history lesson about Greeks and regular polygons approximating circles, and say, well, it looks like the ratio of the circumference to the diameter is getting closer and closer to some number, and that number isn't anything simple like 3, but it turns out to be important, so we should give it a name; and the name we give it is pi.
Either way it's not really a simple concept, certainly not simple enough that it doesn't need explaining.
I got caught in an incredible storm today on my way to Université de Montréal for a seminar. I had to stop cycling because I couldn't see; hailstones were pinging off my head and hands. Luckily there was a bus stop nearby that I got under, soon to be joined by three other adventurers. We stood and laughed at the ferocity of it for a while, before the hail became rain, and I had to head off again to get to the seminar in time. Sitting through the seminar in soaked jeans was unpleasant, but I did emerge just in time to see a fantastic sunset through the mist.
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