Saturday, April 09, 2005


Photo from USA Today.
We didn't get this much snow!

I reported a little over two weeks ago that winter had disappeared in a burst of sunshine and that the daffodils were blooming all over Durham. Well, as much as I hate to bore you with weather reports, as I glanced up from my desk now and then throughout the day today I saw warm sunshine, lovely clouds blowing by, and now a veritable blizzard! Who could predict what is next around the corner?

I've been thinking a bit about randomness recently. You see, I'm trying to paint clouds on our nursery walls and ceiling as we prepare for Bunny's imminent arrival. It's challenging enough to get the transparency right, to add a little gray to the white for texture, to shape them so that distant and close clouds have the right appearance, etc. But the real challenge is to make them random. We humans are generally pretty bad at randomness. If you try to draw a random cloud shape, chances are you'll end up with a circle, an oval, a square, a star, or some other regular shape. My only chance for producing randomness is to look at a photograph of a cloud while I paint--and even then I tend to move toward a regular pattern when I'm not quite concentrating enough. (By the way, the sun just came out.)

Some of the recent pretty clouds out of my office window

I used to think it very funny that the CRC Math Handbook (by the way, in the UK 'mathematics' is abbreviated 'maths', not 'math' as it is in the US) contained tables of random numbers. How could a standard list be random?? But now I see that having a little help in generating randomness is a Good Thing.

I read somewhere recently about a way to demonstrate how bad we are at producing randomness. Ask two friends to produce a list of the outcome of 100 coin flips--one really flips the coin and writes down the results, the other just imagines and produces a list of a 100 H's and T's. It's almost guaranteed (97.2% probability) that the real flipper will have at least one place where there are 5 heads or 5 tails in a row. The imaginative one probably won't. (By the way, here's the Java code to determine that it's 97.2%. Let me know if you find any bugs. And yes, I know it's terrible object oriented programming, so no need to tell me :-).

We're just too predictable to be random. So maybe it's just a little gift when the snow occasionally falls on our daffodils. (And now the sky is almost completely blue!)


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