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grade12
May27-10, 11:54 PM
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?

Nabeshin
May27-10, 11:59 PM
Double the frequency.

Everyone sounds like alvin and the chipmunks.

jtbell
May28-10, 12:49 AM
Because radiowaves travel at c regardless of your relative speed, you should hear them the same as you would on Earth.

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

Fredrik
May28-10, 04:23 AM
it is told that matter and energy bending time and space but matter & energy cant be destroyed than how can time and space become zero at the time of big bang please reply me via email sir i m in very big trouble??????????????//
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 (http://www.physicsforums.com/showpost.php?p=2731666&postcount=3) might help you see some of these things a bit more clearly.

Fredrik
May28-10, 04:26 AM
"relativistic Doppler effect"
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).