Here comes the model situation. I have a man on a planet and two ships. One ship will go straight to from a planet and another one will go opposite direction. Well thats for me very interesting. Because i will travel with ship near to speed of light from earth the earth time will be for me slowed down. But I also traveling on a ship from another ship with doubled speed but thats impossible - nobody can cross a speed of light - so time on other ship must be also very slowed down. And question. When everybody will came back at earth who will be oldest?