Couldn’t we send out two devices in different directions, wait a decade, have them shine light at eachother simultaneously, record when they receive the light, then send the times back to earth?
Your question is good. You’re missing understanding of time dilation and frame of reference. An explanation of the theory of relativity is at least pages long.
The first book I ever read on the subject, and IMO the best introductory text for any non-physiscist, is Stephen Hawking’s “A Brief History of Time”. But, any introduction to relativity should answer your question.
Couldn’t we send out two devices in different directions, wait a decade, have them shine light at eachother simultaneously, record when they receive the light, then send the times back to earth?
Your question is good. You’re missing understanding of time dilation and frame of reference. An explanation of the theory of relativity is at least pages long.
The first book I ever read on the subject, and IMO the best introductory text for any non-physiscist, is Stephen Hawking’s “A Brief History of Time”. But, any introduction to relativity should answer your question.