twins

[IPhO' 2008]

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?

[jtbell]

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."

[Hans de Vries]

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

[HallsofIvy]

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.