I disagree: While you cannot have a clock travelling alongside the photon, you can have a family of clocks travelling along light-like trajectories that have th

I disagree: While you cannot have a clock travelling alongside the photon, you can have a family of clocks travelling along light-like trajectories that have the photon trajectory as its limit. But as I was alluding to with my 'tomayto, tomahto' remark, this is a question of semantics, and we're not really arguing about physics, but labels.