Observer A, who is at rest in the laboratory, is studying a particle that is moving through the laboratory at a speed of v=0.8c
and determines its lifetime to be τA=129 ns. Observer A places markers in the laboratory at the locations where the particle is produced and where it decays. How far apart are those markers in the laboratory?
If the particle has a lifetime of 129 ns as measured by observer A, and has a speed of 0.8c as measured by observer A, the distance between the markers will be:
