Relativity questions

[jajrussel]

In the thought experiments relativity says that my twin will age differently if he is traveling at eighty seven percent of the speed of light relative to me among other things.

 

If, when he is moving at eighty seven percent of the speed of light, I can measure his vehicle, length,speed, etc. Then I assume he can measure things that pertain to me.

 

My assumption is that he will view me as moving at eighty seven percent of the speed if light. His measurements might mirror my own.

 

Is this asumtion right?

 

Also let's say that before the vast difference in velocity we had agreed to communicate on a specific frequency, so that we can compare our measurements. We set the frequency in our radio. When I measure his speed as eighty seven percent of the speed of light I call him on the radio to confirm my measure.

 

Is that frequency still going to work?

[Sriman Dutta]

No. The same frequency is not going to reach you if the other person sends the signal. This is due to Relativistic Doppler Effect.

[jajrussel]

No. The same frequency is not going to reach you if the other person sends the signal. This is due to Relativistic Doppler Effect.

The Doppler Effect, does that apply equally to my twin?

 

As in, if I see red, he sees red? If I see blue he sees blue?

 

I have forgotten the possible combinations,so I removed the question about direction.

Edited October 30, 2016 by jajrussel

[DimaMazin]

You disagree on simultaneity. If you both are approaching you see blueshift. If you are escaping from each other you see redshift.

[Sriman Dutta]

Correct DimaMazin and that's because of the equation -

 

observed frequency = sqrt[(c+v)/(c-v)].original frequency

 

v is positive if both are approaching, else negative.

[mathematic]

The difference in aging is seen because one twin leaves earth to someplace and then turns around and comes back. Therefore it is no longer a symmetric situation.