AST201H1 Lecture Notes - Lecture 2: Special Relativity
14 Jan 2019
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Clicker q: q: you fall asleep on a spaceship and wakeup. How can you tell if the spaceship is moving: a: there is no experiment in the universe to tell whether the spaceship is just staying still or moving. Cannot tell the difference between you staing still and me moving or me staying still and you moving, both equal. We can only measure motion relative to a given frame of reference. Speed of light = c = 299 792. 458 km/sec. Light travels around the world 7. 5 times per second: light always travels at c (in a vacuum, no object with mass can ever reach or exceed light speed. Q: shining light at someone moving away at 0. 9c: a: will see me moving away at 0. 9c but will still see the light moving at c. Foundations of special relativity: we can only measure speeds of objects relative to one another, the speed of light is invariant.
