# Einstein relativity- radiowaves when travelling at v>0.1c

1. May 27, 2010

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?

2. May 27, 2010

### Nabeshin

Double the frequency.

Everyone sounds like alvin and the chipmunks.

3. May 28, 2010

### Staff: Mentor

Nope. Do a Google search on "relativistic Doppler effect".

4. May 28, 2010

### Fredrik

Staff Emeritus
We don't reply by email. The short answer is that there's no such thing as "the time of the big bang", at least not in the simplest big bang theory. The links in the last two quotes in this post might help you see some of these things a bit more clearly.

5. May 28, 2010

### Fredrik

Staff Emeritus
In this case, the spaceship's velocity is perpendicular to the motion of the radio waves, so the only effect that matters is time dilation (assuming that we treat Earth as a point instead of as a big ball).