A and B are twins,A notice B moving away from him with velocity v

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A and B are twins,A notice B moving away from him with velocity v, so A notice that B is youngerv than him (time dilation) , In the same way, B notice that A is younger than him.
What happen?
 
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Search this forum for "twin paradox." There have been many discussions of this. In fact, there's one going on right now, with the title "Need help understanding the twins."
 


IPhO' 2008 said:
A and B are twins,A notice B moving away from him with velocity v, so A notice that B is youngerv than him (time dilation) , In the same way, B notice that A is younger than him.
What happen?

Image 4.26 in section 4.15 (Reversal of Time dilation) explains this all:

http://physics-quest.org/Book_Chapter_Non_Simultaneity.pdf


Regards, Hans
 


IPhO' 2008 said:
A and B are twins,A notice B moving away from him with velocity v, so A notice that B is youngerv than him (time dilation) , In the same way, B notice that A is younger than him.
What happen?
Actually, in this case, nothing is happening! Both are completely correct. Each sees the other as being younger than himself. This only becomes a "paradox" when the two twins are back in the same "frame of reference" (i.e. at rest relative to one another) together again. And that requires acceleration of one of the twins.
 

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