Since an observer traveling through space at the speed of light experiences no time from the beginning of their journey until they decelerate (since their 4-velocity vector has non-zero values only in the 3 dimensions of space), photons don’t just arrive precisely when they mean to, from the moment they are emitted, they have already arrived.
Since an observer traveling through space at the speed of light experiences no time from the beginning of their journey until they decelerate (since their 4-velocity vector has non-zero values only in the 3 dimensions of space), photons don’t just arrive precisely when they mean to, from the moment they are emitted, they have already arrived.