It's also the method by which signals from radio telescopes thousands of miles apart have been correlated after the fact at a central location. This has been the case for a couple of decades now.
What does that have to do with transactions? Analyzing radio signals is simple compared to running transactions, since it is only a one-directional signal flow.
For instance, at the VLBA: https://en.wikipedia.org/wiki/Very_Long_Baseline_Array