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A spaceship travels at 0.80c from Earth to a star 10 light years distant, as measured in the Earth-star reference frame. Let event A be the ship’s departure from Earth and event B its arrival at the star, (a) Find the distance and lime between the two events in the Earth-star frame, (b) Repeat for the ship's frame. (Hint: The distance in the ship frame is the distance an observer has to move with respect to that frame to be at both events—not the same as the Lorentz-contracted distance between Earth and star.) (c) Compute the square of the spacetime interval in both frames to show explicitly that it’s invariant.
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