Chapter 20 - Relativity - Davidson Physics

Announcements Review The Twin Paradox Length Contraction Final QuestionsA paradox?Clocks on a space ship run slower than clocks on EarthFrom the point of view (frame of reference) of the astronaut in the space ship,Earth is moving away from him, so clocks on Earth should run slower than clocks on the ship!It would seem that by symmetry, both the astronaut and his twin will observe the other as aging slower.Who is right?QuestionsAre the two cases truly symmetric?Is there anything that distinguishes the astronaut from the twin?AnswerThe two cases are not symmetricThe astronaut is distinguished from the twin because the astronaut must accelerateSpecial relativity does not claim that all observers are equivalent (only that observers at rest ininertial reference frames are equivalent)Because the astronaut must accelerate (speed up, slow down, turn around, etc.), he is not alwaysat rest in an inertial frame of referenceRelativity