Suppose you measure the red shifts of all the images produced by gravitational lensing
Chapter 34, Problem 14(choose chapter or problem)
Suppose you measure the red shifts of all the images produced by gravitational lensing, such as in Figure34.12 you find that the central image has a red shift less than the outer images, and those all have the same red shift. Discuss how this not only shows that the images are of the same object, but also implies that the red shift is not affected by taking different paths through space. Does it imply that cosmological red shifts are not caused by traveling through space (light getting tired, perhaps)?
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