## Tuesday, October 19, 2004

### Rain and green beans

What is the most remarkable thing about the rain? It's not that it is wet. I have gone all over the world to ask this question, and always that answer. No, the most remarkable thing about the rain is that it stops. And that makes all the difference.
-- B. Kedem

That the rain stops is mathematically interesting because it means any reasonable model of rainfall will have to have both a continuous component (the distribution of rainfall rates when it isn't raining) and a discrete component (since there is a finite probability that there is no rain). Depending on your cultural biases, you might describe this mixed distribution by blindly throwing about Dirac delta symbols, or you might proceed with a more careful description in terms of measure theory or the theory of distributions. Or you might never make it past the radio forecaster's discrete summary: 80 percent chance of rain tomorrow.

As I listened to the downpour on the roof this morning, I was not thinking (exclusively) of sigma algebras and the most remarkable thing about the rain. Mostly, I thought about umbrellas and puddles, and contemplated whether the most remarkable thing about the rain would assert itself in time for me to avoid observing the most obvious thing about the rain on my way to a meeting. The rain didn't stop, but it did slow down some, and so I didn't have to pull the Emergency Dry Socks from their usual home behind my file of papers on security in distributed systems.

The rain had stopped by this evening, but I still was happy to accept the ride to the grocery store proferred by one of my buddies from the department. In the interest of getting a little more balance in our respective diets, I invited him to share dinner afterward, and we had miso salmon, stir-fried green beans with garlic and peanuts, French onion soup (or pudding, perhaps -- the bread:broth ratio was high), green tea, and yogurt with fruit and honey. And then I gave him back his copy of Fermat's Enigma, and we went back to the office to return to our respective tasks.

Food does affect my attitudes in the most wonderful ways sometimes. And warm tea is good for turning thoughts on wet socks toward thoughts of napping to the patter of rain on the roof.

• Currently drinking: Rooibos