APS News

The Twin Paradox, Redux

Einstein Einstein
Photo Credits: Jessica Clark

Two Einsteins mysteriously showed up at a December meeting of the National Science Teachers Association in Richmond, Virginia, to advertise the World Year of Physics. In the photo at left, one Einstein, dressed casually in 21st-century clothes, had aged normally. The other one, dressed in clothes more typical of the early 20th century, had been travelling close to the speed of light. Furthermore, due to the Lorentz contraction, he was as thin as a piece of cardboard.

In the photo at right, the modern-day Einstein (aka Marc Spiegel) explains the fine points of general relativity to Logan Lee of Savannah, Georgia and his father, Jason Lee.

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Editor: Alan Chodos
Associate Editor: Jennifer Ouellette