Twin Paradox: Relation between Age and Speed of light .

[Aero_Arnendu]

Hey Friends,
In Einstein's special relativity I find "Twin Paradox", where Dick and Jack, two twins . one of them went to space at a speed of 0.80c to a star 20 light year away (where c is the speed of light) and other remains on earth. When Jane returned to Earth his age was 50 but who stayed in earth, Dick, his age was 70.
I find a formula there : √1 - v²/c²
My question is how is it find and why Jane was younger than Dick ??
Thank you..

 

[PeterDonis]

See the Usenet Physics FAQ article on the twin paradox:

http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_paradox.html

 

[Aero_Arnendu]

thank you to help me..