This is a true or false question. I think I heard this idea somewhere. But first, I need to describe the context.
Consider two electrons that are traveling side-by-side at a constant speed in a straight line. There is a combined electric repulsive force and a magnetic attractive force. However, in the reference frame moving with the electrons, there is only the repulsive force. This apparent contradiction between the stationary and moving reference frame is resolved by recognizing the invariance of Maxwell's equations under Lorenz transformations.
The Question Setup
A solid object maintains its length via the quantum effects in its atoms which ultimately depend on electrodynamic forces. Consider the object in motion. The view from a rest frame must include the changes due to motion in the EM forces, which ultimately effect the length of the solid. This must give the same result as measuring the length in a frame moving with the object and then applying the Lorenz transformations.
A similar discussion can be applied to the elasticity of a clock spring and its internal EM forces. Or to the biological chemistry that effects our aging and sense of time.
Is this analysis correct? Is there a reference?
I would not apply this type of analysis directly to the nuclear force and rate of decay.