Recall that a raisin cake is sometimes used to imagine how an expanding universe behaves. Suppose you are in a uniformly expanding raisin cake, sitting on Raisin A, looking at Raisin B, 2 cm away from you. Raisin B is moving away from you at 1 cm/sec. At the same time, you observe another Raisin C, which is moving away from you at 3 cm/sec. How far away is Raisin C from Raisin A?

Question

Quizplus · Accepted Answer

In a uniformly expanding universe, the velocity at which an object moves away is proportional to its distance. If Raisin B is 2 cm away and moving at 1 cm/sec, then Raisin C, moving at 3 cm/sec, must be 6 cm away from Raisin A.

Recall That a Raisin Cake Is Sometimes Used to Imagine