The Twin Paradox The “twin paradox” is not a paradox in the
sense of a logical contradiction that falsifies relativity but
rather a very curious puzzle. Traditionally, the twin paradox is
concerned with the strange result that if one of two twin
brothers leaves the other and embarks on a high-speed journey to
a remote point and back again, the twins will no longer be the
same age. Let’s call these hypothetical twin brothers A and B.
For this discussion, we’ll stipulate that A stays home while B
travels away from his brother at a speed of 60 percent of the
speed of light (0.6c, where c is the speed of light, nearly 300
million meters per second). B travels for fifteen years by A’s
reckoning then quickly decelerates to a stop, turns around, and
quickly accelerates back to 0.6c in the direction toward his
brother, A. After another fifteen years (again, by A’s
reckoning), B arrives home, decelerates, and rejoins his
brother, who has aged thirty years since he last saw B. The
“paradox” is that, even though A’s vel