A second of time is defined as x oscillations of a cesium atom's resonant frequency, and is commonly measured in atomic clocks. If an atomic clock is propelled at near the speed of light (or at any speed), wouldn't that definition of a second be distorted? If so, shouldn't we add a longitude and latitude to the definition since all places on earth travel at different speeds?

Asked by: Ryan Gallagher


A second of time can only be defined relative to the observer. Whether you determine the passage of one second of time with a stopwatch or a Cesium 133 atom, you want the source of that measurement to be in your own inertial frame. What you are measuring is the passage of LOCAL time. There is no universal inertial frame of reference that can determine an 'absolute' second to correct for.
Answered by: Paul Walorski, B.A. Physics, Part-time Physics Instructor