magine an alien spaceship traveling so fast that it crosses our galaxy (whose rest diameter is 100,000 ly) in only 100 y of spaceship time. Observers at rest in the galaxy would say that this was possible because the ship's speed B was so close to 1 that the proper time it measured between its entry into and departure from the galaxy was much shorter than the galaxy frame coordinate time (~ 100,000 y) between those events. But how does this look to the aliens? To them, their clocks are running normallu, but the galaxy, which moves backward relative to them at speed B~1, is Lorentz-contracted to a bit less than 100 ly across: this is what makes it possible for the whole galaxy to fly by them in only 100 y. Then find the diameter of the galaxy in the aliens' frame, and verify that it is possible for a galaxy moving at speed B with this diameter to passthe aliens' ship completely in 100y.

magine an alien spaceship traveling so fast that it crosses our galaxy (whose rest diameter is 100,000 ly) in only 100 y of spaceship time. Observers at rest in the galaxy would say that this was possible because the ship's speed B was so close to 1 that the proper time it measured between its entry into and departure from the galaxy was much shorter than the galaxy frame coordinate time (~ 100,000 y) between those events. But how does this look to the aliens? To them, their clocks are running normallu, but the galaxy, which moves backward relative to them at speed B~1, is Lorentz-contracted to a bit less than 100 ly across: this is what makes it possible for the whole galaxy to fly by them in only 100 y. Then find the diameter of the galaxy in the aliens' frame, and verify that it is possible for a galaxy moving at speed B with this diameter to passthe aliens' ship completely in 100y.

Similar questions

The Lorentz contraction formula in relativity theory relates the length L of an object moving at a velocity of v mi/sec with respect to an ob- server to its length Lo at rest. If c is the speed of light, then L2 = Lo2 (1- v2 / c2) For what velocities will L be less than L.? State the answer in terms of c.
A spaceship, moving away from Earth at a speed of 0.900c, reports back by transmitting at a frequency (measured in the spaceship frame) of 100 MHz. To what frequency must Earth receivers be tuned to receive the report?
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