As physicist Clifford Johnson notes in a Cosmic Variance post, Sunday the 29th was the anniversary of a powerfully symbolic event. As Johnson says: “On January 29th 1931, Edwin Hubble took Einstein up Mount Wilson to see the famous 100 inch telescope where Hubble had done at least two revolutionary things (with the aid of Henrietta Leavitt’s remarkable work on variable stars): (1) He demonstrated that the Milky Way Galaxy, where we live, is not the entire universe, but just one of many galaxies, and (2) He confirmed (ahem, not discovered) that the universe was expanding and (with Humason…who started out as the janitor at the observatory) quantified it in what we now call “Hubble’s Law”.
And don’t miss Johnson’s wonderful Walk Up Mount Wilson, complete with photographs, further background and the story of a wonderful morning hike. For a man who long resisted writing for a weblog (and for eloquent reasons), Johnson’s posts have become simply indispensable.
