Doppler Effect: Light Blueshifted When Source Moving Towards Observer

[kent davidge]

If I and the light source are both moving toward one another, I see light blueshifted. What if I'm at rest and the source moving towards me?

 

[Orodruin]

At rest relative to what? You have asked enough questions in the relativity forums to know that there is no absolute rest and that being precise in formulations is important. You should also post your own work, not just say that you "seem to get" something.

 

[Vanadium 50]

I've worked out the equations

Not correctly. If you did it correctly, a source moving towards you would be blueshifted.

 

[kent davidge]

At rest relative to what?

Self evident. I do not believe I would have to make that explicit to a experienced physicist like you.

a source moving towards you would be blueshifted.

Indeed, as soon as I posted this question, I realized where I was going wrong, and got the correct result.

 

[Nugatory]

At rest relative to what?

Self evident. I do not believe I would have to make that explicit to a experienced physicist like you.

Not only is the answer not self-evident, but I am unable to imagine any possible answer. As you posed the problem, there are only two things to consider: you and the light source, and these certainly are not at rest relative to one another.

 

[Nugatory]

The original poster says they've found their error so this thread is closed.
The key point here is that it is the exact same physical situation whether we think in terms of the light source approaching the observer or the observer approaching the light source; neither is more "at rest" than the other.
As always, if you have more to say on the topic, PM me or any other mentor.