Jean-Marc Lévy-Leblond

# From relativity to chronogeometry

## The twin paradox (re)$^n$visited and (finally?) tamed

Jean-Marc Lévy-Leblond
University of Nice

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?

Snippet from Wikipedia: Jean-Marc Lévy-Leblond

Jean-Marc Lévy-Leblond (born 1940) is a physicist and essayist. After a doctorate in Theoretical Physics at the université d’Orsay in 1965, he was successively in charge of research at CNRS, lecturer at the université de Nice, a professor at the Paris Diderot University, and at Nice, where he taught in the departments of physics, philosophy and communication. Since 2001, he has been Professor Emeritus at the Université de Nice and is program director at the Collège international de philosophie. He has published many articles on theoretical physics, mathematics and epistemology. He founded and directs the journal "Alliage (culture, science, technique)", directs the collection "Science ouverte" at Seuil, and works more generally for the use of science in culture.

Manucius
ISBN 2845781458
Jean-Marc. Lévy-Leblond
ISBN 8883232305
Lévy-Leblond Jean-Marc, Lehoucq Roland, Schaer Roland Balibar Françoise
ISBN 2746507676
Jean=Marc Levy-Leblond
ISBN 2020881667
A. Jaubert/J. M. Levy-Leblond
ISBN 2020042622
Jean-Marc Levy-Leblond, Francoise Balibar
ISBN 0444881204