So my grade 12 physics teacher asked our class this question which he didn't have an answer to. Suppose I am in a spaceship travelling at 0.9c around the Earth. Because of time dilation, let's say 50 years (relative to me) have passed. Let's also say, for simplicity, that 100 years have passed relative to someone on Earth. Let's say i am listening to an Earth radio station. For all of those 50 years. Because radiowaves travel at c regardless of your relative speed, you should hear them the same as you would on Earth. But my question is this: What would 100 years worth of radio sound like, when you're hearing it all in only 50 years?