<sod>In physics, the '''twin paradox''' is a [[thought experiment]] in [[special relativity]] involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling because each twin sees the other twin as moving, and so, according to an incorrect naive<ref>{{cite book |title=From Special Relativity to Feynman Diagrams: A Course of Theoretical Particle Physics for Beginners |edition=illustrated |first1=Riccardo |last1=D'Auria |first2=Mario |last2=Trigiante |publisher=Springer Science & Business Media |year=2011 |isbn=978-88-470-1504-3 |page=541 |url=https://books.google.com/books?id=R-qIh6kd8d0C}} [https://books.google.com/books?id=R-qIh6kd8d0C&pg=PA541 Extract of page 541]</ref><ref>{{cite book |title=Gravitation and Spacetime |edition=3rd |first1=Hans C. |last1=Ohanian |first2=Remo |last2=Ruffini |publisher=Cambridge University Press |year=2013 |isbn=978-1-139-61954-7 |page=176 |url=https://books.google.com/books?id=JVQhAwAAQBAJ}} [https://books.google.com/books?id=JVQhAwAAQBAJ&pg=PA176 Extract of page 176]</ref> application of [[time dilation]] and the [[principle of relativity]], each should paradoxically find the other to have aged more slowly. However, this scenario can be resolved within the standard framework of special relativity: the travelling twin's trajectory involves two different inertial frames, one for the outbound journey and one for the inbound journey, and so there is no symmetry between the spacetime paths of the two twins. Therefore, the twin paradox is not a [[paradox]] in the sense of a logical contradiction.<eod>
<sod>In physics, the '''twin paradox''' is a [[thought experiment]] in [[special relativity]] involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. This result appears puzzling because each twin sees the other twin as moving, and so, according to an incorrect naive<ref>{{cite book |title=From Special Relativity to Feynman Diagrams: A Course of Theoretical Particle Physics for Beginners |edition=illustrated |first1=Riccardo |last1=D'Auria |first2=Mario |last2=Trigiante |publisher=Springer Science & Business Media |year=2011 |isbn=978-88-470-1504-3 |page=541 |url=https://books.google.com/books?id=R-qIh6kd8d0C}} [https://books.google.com/books?id=R-qIh6kd8d0C&pg=PA541 Extract of page 541]</ref><ref>{{cite book |title=Gravitation and Spacetime |edition=3rd |first1=Hans C. |last1=Ohanian |first2=Remo |last2=Ruffini |publisher=Cambridge University Press |year=2013 |isbn=978-1-139-61954-7 |page=176 |url=https://books.google.com/books?id=JVQhAwAAQBAJ}} [https://books.google.com/books?id=JVQhAwAAQBAJ&pg=PA176 Extract of page 176]</ref><ref>{{cite book |title=The Future of Post-Human Mathematical Logic |first1=Peter |last1=Baofu |publisher=Cambridge Scholars Publishing |year=2009 |isbn=978-1-4438-0621-3 |page=105 |url=https://books.google.com/books?id=HKYYBwAAQBAJ}} [https://books.google.com/books?id=HKYYBwAAQBAJ&pg=PA105 Extract of page 105]</ref> application of [[time dilation]] and the [[principle of relativity]], each should paradoxically find the other to have aged more slowly. However, this scenario can be resolved within the standard framework of special relativity: the travelling twin's trajectory involves two different inertial frames, one for the outbound journey and one for the inbound journey, and so there is no symmetry between the spacetime paths of the two twins. Therefore, the twin paradox is not a [[paradox]] in the sense of a logical contradiction.<eod>