Arrived LIGO

Rattlesnake Ridge and the LIGO beamtube snaking off into the desert. Sunset, May 22, 2006.

I arrived at LIGO yesterday afternoon, via a backroad that dumped me directly onto the unnamed, officially-doesn't-exist road through Hanford Nuclear Reservation that takes you to LIGO. My whole trip from Portland to LIGO was, if not on backroads, circuitous. I attended the eruption of Mt. St. Helens. I attended the demolition of the Trojan Nuclear Station. I took highway 97 up from the Gorge into Eastern Washington and the trees fell away to the desert, rolling planes of sagebrush. It was raining lightly and the desert is colorful, its usual brown expanse tinted green with new growth, Rattlesnake Ridge in the distance tinted a hazy purple through the atmosphere. The rain on the soil makes the desert air thick, refreshing, and sweet-smelling. On the LIGO campus, outside the labs and offices, birds flitted and chirped through the light rain.

The glorious old sign that used to greet us on that unnamed, doesn't-exist road is gone now. I've only been coming to LIGO for a little over a year and I can see the development along the highway, the new tract housing projects and golf courses, completely incongruous out here in the desert.

At the LIGO lab I wandered around until the operators, seeing me on the site surveillance cameras, came out to ask me who I was and let me in. The lab was all but abandoned, just the Operator and the "SciMon" (that's what I'll be) in the darkened control room, watching the wiggle of charts and graphs, projected onto the wall like Mission Control. In the cool darkness we tinker at computer terminals, each terminal sprouting several large flat panel displays, each of us investigating idiosyncracies of the Interferometers. At some point one of the computers starts emitting a regular beeping. There's a roar of audio from a little speaker—the instrument's output, the signal that should indicate the wigges of gravitational waves, but is corrupted by any local disturbances too, is fed directly to a speaker, so "listening for gravitational waves" is a less metaphorical phrase than might be assumed. (Though any real gravity waves will not be detected by a human listening but by extremely sensitive computer programs.)

The operator and the scimon scramble to action on their computer terminals. The Interferometers have crashed, "lost lock." The mirrors of the laser system are held by the computer control systems in a delicate balance to detect the faintest strains of gravity. Local wiggles of the earth can totally overwhelm this delicate balance. The Operator works swiftly to regain control of the Interferometer, to get it into lock again. The scimon works to find out why lock was lost at all. We look at seismographs from Rattlesnake Ridge and from on-site at LIGO. We see wiggles out in the X-arm of the interferometer: the ground was moving out to the East, a tiny vibration most likely resulting from construction out on Hanford site. Hypothesized cause is noted in the logbook. Lock is regained. Data-taking resumes. The operator and scimon go back to what they were doing before.