time dilation

time dilation

Time dilation is a phenomenon predicted by the special theory of relativity in which the passage of time in the frame of reference of a moving object slows down as the object approaches the speed of light. Effectively, this makes it possible to spend energy to buy time. Time dilation has been experimentally confirmed using cesium clocks that can measure extremely small periods of time.


A potentially important consequence follows for future interstellar flight. Simply by traveling fast enough, an astronaut can reach any destination within a specified amount of (shipboard) time. The table below gives the travel times, as measured by onboard clocks, to Arcturus, located 36 light-years (11 parsecs) from the Sun, for a spacecraft traveling at various speeds (given as fractions of the speed of light, c).


Shipboard travel times to Arcturus at various speeds
Speed 0.1c 0.5c 0.9c 0.99c 0.999c
Travel time 358.2 years 62.4 years 17.4 years 5.13 years 1.61 years


Impressive though these results seem, they do not take into account the profound human problems which would surely follow from time dislocation.