Wrote an essay on why time is such a hard problem in distributed systems.
This week, I went down the rabbit hole of clock drift, NTP, PTP, logical clocks, vector clocks, and how systems like Spanner and CockroachDB deal with ordering, and causality at scale.
If you want to know how and why clocks break databases, why milliseconds matter, or how distributed systems deal with time, this essay will give you a solid mental model. Give it a read.