simfoma me ti theoria tis sxetikothas tou Einstein to taksidi sto xrono theoritika einai efikto alla mono pros ta empros dhladh pros to mellon gia kapoion o opoios kineite me taxythta konta se aythn tou fotos. An kappios omos kataferei na xeperasei thn taxythta tou fotos tote theorhtika pali paei piso sto xrono dhladh kanei ena taxidi pros to paralthon. Apo aftes tis theories prokyptoun kai ta 2 antistoixa paradoxa: 1) to paradoxo ton didimon kai 2) to paradoxo tou pappou.