Relativistic travel and time dilation
Compare Earth and traveler elapsed time at a constant fraction of light speed. Change the inputs to update the chart or diagram.
Your inputs
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How it works
- = v/c; γ = 1/√((1 − )(1 + )); t = /v; τ = t/γ; d′ = /γ
Input and formula key
Your result
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Assumptions and limitations
One-way inertial travel in flat spacetime; distance is measured in the Earth frame. Acceleration, braking, gravity and turnaround are excluded. One Julian year is 31,557,600 seconds and c is exactly 299,792,458 m/s. This is real special relativity. Example: 4 light-years at 80% c take 5 Earth years and 3 traveler years, with γ = 1.666667.
Sources
- Einstein Online — light clocks and time dilation Sources reviewed: 2026-10-22
