three spaceships, two moving at 0.9C and the 3rd stationary relative to the first two. the two moving ships are 1 LY apart but moving in the same direction toward the 3rd ship. as the first of the two moving ships passes the 3rd (stationary) ship, the ship which is now 1 LY from both the other ships emits a photon.(adsbygoogle = window.adsbygoogle || []).push({});

since the distance from the emitting ship and the stationary ship is 1 LY, it will take one year for the photon to reach the stationary ship, acccording to the clock on the stationary ship. however, because time measurement is different for the stationary ship and the ship which passed it as the photon was emitted, it will also take only 1 year for the photon to reach the other ship (by its on-board clock).

1. according to the clock on the stationary ship, it will take nearly two years for the photon to reach the moving ship - correct?.

2. according to the moving ship's clock, it only took 0.1 year (? - something well less than a year, at any rate) for the photon to reach the stationary ship - correct?

from the stationary ship's perspective, the distance between the two moving ships is a constant 1 LY - why wouldnt it measure exactly one year for a photon to move from one ship to the other?

from the moving ship's perspective, it was clear that the stationary ship was exactly 1 LY from the other ship when the photon was emitted - why should it measure less than a year for the photon to reach the stationary ship? how can it reconcile the idea that the photon traveled 1 LY in less than a year?

thanks.

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# A simple SR question, but confusing to me

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