People who take measurements of physical artifacts do some amazingly clever things. I went to a meeting on Thursday where there were two talks. The first talk was about measurements of the waves going through a high frequency piezoelectric resonator. Think of waves rippling across the surface of a drum. Now think of trying to measure the shape of those waves -- when the drum is only tens of micrometers across, the surface of the drum moves only a few nanometers, and about two billion waves pass through a point in one second. It seems more fanciful than trying to count how many steps are made by a collection of angels furiously tap-dancing on the head of a pin. But by bouncing a laser off a mirror sitting atop an atomically sharp tip on the drums surface, the first speaker managed to measure the shapes of those waves with startling accuracy. The second speaker was working on building and tuning the types of devices that the first speaker measured. I think both the construction and the measurement are awe-inspiring.

The fact that we understand as much about fluid dynamics as we do is equally awe-inspiring, though in a different way. So much nonlinearity! I spent some time Friday afternoon photocopying the fluids notes on reserve in the library. I copied most of the material after the basic tensor calculus and continuum mechanics at the beginning of the course; at the end, I had exactly a hundred pages of material. It will be a good supplement to reading the text by Batchelor.

I went with Winnie to the UC ballroom dance Fall Ball on Friday. I'm not much of a dancer, and doubt I ever will be. It turns out that Winnie feels much the same, but it was a chance to catch up with old friends and to get dressed up. I hope that the dance made up for the time she spent in traffic; the traffic from the South Bay to the East Bay is apparently surprisingly dense on a Friday afternoon.

Yesterday, we walked along the Golden Gate Bridge. It was a good day for such a walk. We're experiencing a final burst of hot weather, and the breeze from the Bay somewhat balanced the heat of the sun. The bridge really does offer some postcard views. It's possible to see so much in one glimpse: the buildings of San Francisco, the hills of the East Bay, the woods of the park at the San Francisco side, and the boats sailing out of the docks on the Sausalito side. It takes only a little imagination to see the hills and water and trees, to see how it attracts so many residents, and to see how powerful the geological forces that shaped the region must be. The bridge itself is interesting, too, but the structure doesn't compare to the landscape. Actually, we passed three bridges yesterday: the Bay Bridge, the Golden Gate Bridge, and the Richmond Bridge. All are interesting in their own ways.

There is a book by William Gibson, Virtual Light, in which much of the action takes place on the Bay Bridge, in a future in which, after an earthquake made it undriveable, people wandered onto the bridge and made it a sort of city unto itself. I was reminded of it a little yesterday.

It was another good weekend for food, too. I made ham and white bean soup on Friday night, and had eggs scrambled with ham and onions for brunch on Saturday. On Saturday night, we had a mushroom-spinach stuffed crust pizza from Zachary's Pizza, and this morning there were bagels from Noah's Bagels, which Patxi and Esther picked up. We finished off the Monk's Blend tea on Saturday night, too; I think I will have to get some more. I also continue to enjoy having an occasional bowl of yogurt and raisins with honey and cinnamon. And there is a baguette in the kitchen which seems to be calling my name now. Ah, food.

Daylight savings time ended last night, and I have turned back all the clocks except the one on my laptop. At some point, I will convince the computer to change its clock as well, but right now it doesn't seem worth the bother. Linux keeps a software clock which is semi-independent of the hardware clock, and so changes I make to the clock setting seem to get lost when I put my machine to sleep. It's probably an easy thing to correct, but it's easy enough to subtract an hour mentally, too.

• Currently drinking: Coffee