From relativity to chronogeometry

Abstract

After a brief historical review of the birth and development of the twin paradox in Einsteinian relativity, some of the still current misunderstandings and misinterpretations will be clarified. I will suggest that assessing (and naming) Einsteinian relativity as a chronogeometry offers a way out to many of its pseudoparadoxes, including the twin paradox. Two new scenarios will the be proposed generalizing the standard story and enabling some deeper understanding. First, Aesop’s fable “The Hare and the Tortoise” is considered in the light of Einsteinian chronogeometry. It will be shown that the Hare, while arriving later than the Tortoise, may still be the winner of the race — or at least may consider itself to be. Second, the situation is considered where the twin initially left at home decides to catch up his brother during his travel. Can they meet so that they may celebrate a common anniversary and recover the same age?