Tweelingparadox

Tweelingparadox is the Dutch term for the twin paradox, a thought experiment in special relativity that illustrates time dilation and the relativity of simultaneity. The setup involves two twins: one stays on Earth while the other travels at relativistic speed to a distant location and then returns. In the Earth frame, the outbound and inbound journeys take time equal to distance divided by speed. The traveling twin’s clock, however, runs slower by the Lorentz factor γ = 1/√(1−v^2/c^2), so the traveling twin ages less over the round trip.

A simple illustration: if the destination is four light-years away and the ship travels at 0.8c, the Earth frame measures a 5-year leg for each direction, for a total of 10 years. The traveling twin experiences τ = 2×(5/γ) years, with γ ≈ 1.666, giving about 6 years of aging for the traveler versus 10 years for the stay-at-home twin. The apparent paradox arises from treating the situation symmetrically, but the traveling twin does not remain in a single inertial frame: during acceleration and turnaround, the symmetry is broken, and different sections of the worldline contribute differently to proper time.

Resolution and interpretation rely on Minkowski spacetime: proper time along a worldline is the integral of dτ = dt/γ, and the stationary twin’s worldline is longer in proper time than the traveling twin’s. The paradox has been discussed since Einstein’s era and is reinforced by real-world confirmations of time dilation, such as precision clock experiments and particle decay observations. The Tweelingparadox remains a standard example illustrating counterintuitive aspects of relativity.