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Intergalactic Dating

(Quick question.) Harold and Henrietta are dining tête-à-tête in the dining room of a spaceship moving forwards with speed v=0.9c. Harold is facing the rear of the spaceship and Henrietta, opposite him, is facing the front. At one point in the conversation, they both agree to simultaneously raise their wine glasses. The raised glasses are separated by exactly tex2html_wrap_inline104 across the table, as perceived by Harold and Henrietta.

  1. Draw a diagram of Harold and Henrietta, the glasses, and the spaceship.
  2. To an observer outside the spaceship, looking into the window of the dining room as it whizzes by, what is the separation of the two glasses? Express your result in cm.
  3. According to the same external observer, which glass is raised first? Harold's? Henrietta's? Or are they both raised at the same time?
  4. Describe in your own words, succintly, two astrophysical situations in which relativistic physics exerts a detectable influence over orbital motions.

Astronomy 7
Fri Sep 17 15:48:25 PDT 1999