When I read that Google installed their own atomic clocks in each datacenter for Spanner, I knew they were doing some real computer science (and probably general relativity?) work: https://www.theverge.com/2012/11/26/3692392/google-spanner-a...
...but there is a lot of noise in those software papers, too - you are often disappointed by fine print, or have good curators/thought-leaders [2] - we all should share names ;)
enjoying the discussion though - very timely if you ask me.
-L, author of [1] below.
[0] - The original Calvin paper -
https://cs.yale.edu/homes/thomson/publications/calvin-sigmod...
[1] - How Fauna implements a variation of Calvin -
https://fauna.com/blog/inside-faunas-distributed-transaction...
[2] - A great article about Calvin by Mohammad Roohitavaf - https://www.mydistributed.systems/2020/08/calvin.html?m=1#:~....
That only applies if the clocks are within 1ms of each other, so around 100 miles (or equivalently: within a single cloud region), and only came in to force in 2014.
The bound that Spanner-likes keep is ~3ms for datacenters across continents, and that was in 2012.
Pure speculation on my behalf though.
ChatGPT likely won't help - but you could look into the fact the the earth isn't round, being an oblate spheroid with 20km less radius at the poles than the equator.
Of course the fact the ideal WGS84 ellipsoid, the official mean global sea level, and the geoid (gravitational surface of equipotential) don't all align must surely come into play here - and that bloody great "gravitational hole" somewhere south of Ceylon.
https://www.e-education.psu.edu/geog862/node/1820
I just felt like pointing out a rabbit hole that some might like to dive into!