Usually when defining lengths in terms of an artefact you use the rest frame of the artefact (i.e. the one in which the artefact is longest).
Doesn’t the time required to traverse the rest length of an artifact vary between observers? Edit: Also, how does knowing the length some other observer sees useful at all?
Usually when defining lengths in terms of an artefact you use the rest frame of the artefact (i.e. the one in which the artefact is longest).
Doesn’t the time required to traverse the rest length of an artifact vary between observers? Edit: Also, how does knowing the length some other observer sees useful at all?