Friday, May 22, 2009

Something for the Bank Holiday weekend

It must have been 6.15 p.m. when Clare popped her head round the door and said "Come and look at this ...".

"Another rabbit?" I said with resignation as I eased myself out of the chair, but she shook her head. I guess I should have realised she wasn't using her 'look-what-the-cat-brought-in' voice.

The ground-floor toilet ceiling had that curious dimple with which I'm wearisomely familiar, a kind of six millimetre three dimensional Gaussian with a small drop of water dangling from the bottom. Other ominous patches were visible in the surrounding plaster. Yes, we were in plumbing hell again.

I bounced upstairs, Clare following with a torch, to a rendezvous with the boiler, which is caged in a network of unlabelled copper pipes, gauges and valves which ongoingly taunt me with their vast incomprehensibility.

Squashed between the cylinder and the wall, as accessible as the fanbelt in a sixties mini, was a cone-shaped cutaway section of pipe. What looked like overflow water was gurgling and chuckling as it spattered down, stray drops running down the outside of the pipe and onto the sodden floor beneath.

To a first approximation, and speaking strictly as a layperson, prima facie evidence of a leak.

Nothing for it but to invoke our maintenance contract with British Gas. Clare got on with the job while I tried to deal with matters in my hopelessly impractical way, lodging a fan heater at an awkward angle to dry out the flooring, and shoving some kitchen roll in to catch further run-off.

Someone is apparently coming tomorrow afternoon.

And to that point, the day had been going adequately well. I spent a small fortune at the opticians on varifocal plus reading glasses, complete with differentially-hued photo-reactive lenses. Brown for general and grey for reading - matches the frames although this seems to have been by accident.

Then this afternoon: two solid hours of reviewing orbital angular momentum and spin, taking copious notes and trying to figure out whether the act of applying quantum operators corresponding to observables to state vectors ever maps, as such, into any procedure performed in an actual experiment.

As I understand it, the utility of the operator lies in defining eigenfunctions and eigenvalues which, so to speak, establish the set of possible observables when an experiment is 'subsequently' carried out. The operator then bows out, its job being done.

Experiments are all about computing the evolution of the state vector and then reading off amplitudes (leading to probabilities) in the basis of the chosen observable at the space-time locations of interest.

What a puzzle quantum mechanics is, and how much easier than plumbing.

Update 9 p.m. The cat just caught a rabbit which, by dint of frantic chasing around, we have managed to let escape into the back garden. The cat is under house-arrest for twenty minutes. Clare is looking increasingly frazzled ...