Error014

Last time I figured out the following example but I preferred to quit since the discussion had become too hot
Summing up

In may opinion the twin paradox is a direct consequence of the special relativity only but Joey posted some articles whereas it seems the time shift entails a change of speed
I must confess I had some doubt
I would appreciate to get your comments as well as Joey's and any others having some interest in this stuff

The example is :

When the starcraft reaches the cruise speed V = 0.95 C the instrumentation on board start transmitting the pilot's heart beats
On the earth the frequency is f = 60 beats / minute
The twin brother, a doctor, doesnt know the theory of relativity therefore he would expect to receive the beats at a time interval T = 1 + 0.95 = 1.95 secs but he gets
T = 1 + 3.20 = 4.20 secs
He makes the false but consistent assumption that his brother's heart, on board, beats at a frequency f = 18.75 beats / minute
Same consideration on his return
Conclusion : The doctor would not be surprised if his brother twin looks younger than him

What's your comment ?