Dr. David Kirkby said: > I can���t see how knowing who posted what first on Facebook, Instagram etc > affects the user experience, when differences in time are any less than a > second. It doesn't make any difference to the people which of two really-close events happens first. What does matter is that separate data centers agree. It's a data base issue rather than a user interface issue. Google put atomic clocks in all their data centers. Spanner: TrueTime and external consistency https://cloud.google.com/spanner/docs/true-time-external-consistency ---------- Many years ago, it wasn't quite uncommon for Unix shops to get into trouble because the time on their systems weren't consistent. I forget the details. It involved NFS - Network File Systems and time on the NFS server being different from the time on the workstation used to edit a file. This looks like a good summary: why does NFS require synchronized system clocks? https://unix.stackexchange.com/questions/549550/why-does-nfs-require-synchroniz ed-system-clocks -- These are my opinions. I hate spam.