Yesterday I managed to stop my walk about 300 meters short of my Leg 28 destination. Today I got there.
A week ago Friday I crossed the state line into Washington. I would have blogged that but Friday I also departed for a real life weekend event, and by the time I got back I figured I might as well wait until I reached the end of the leg, but then that took longer than expected due to the heat wave in my real life location. Anyway, I was in Oregon for 29 days, just passing through this time. I went northwest through Kennewick and today reached a great big L-shaped facility: the LIGO Hanford Observatory.
Aerial view of the LIGO detector in Hanford, Washington. Credit: LIGO Laboratory.
LIGO stands for Laser Interferometer Gravitational-Wave Observatory. It consists of two sites, one here in Washington and one in Livingston, Louisiana. Each site houses a large — four km by four km — laser interferometer designed to detect gravitational waves emitted by mergers of distant neutron stars and black holes. The first such detection, the first detection by anyone of any gravitational waves, occurred on 14 September 2015. As of January 2022 LIGO had observed 90 gravitational wave events.
There are two sites because real gravitational waves should produce signals in interferometers placed anywhere on Earth, while false signals due to various sources of background can be expected to be seen at one site only. So a detection is only counted if it’s seen at both sites.
It’s a remarkable technological achievement. What they are looking for is stretching and contracting of the two 4-km interferometer arms by an amount 10,000 times smaller than an atomic nucleus! And this tells us about black hole mergers taking place billions of light years away.
I’ve gone about 7 km further on, continuing in the northwest direction on Leg 29.
A map showing my progress is here, a spreadsheet with progress detail is here, and a Google Earth KMZ file is in this Google Drive folder. Present coordinates: 46.503°N, 119.424°W.
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