Lamport drew the notion of 'happens before' from special relativity: just as one event can influence another via light-speed-limited signals in physics, in distributed systems one event can influence another via messages actually sent in the system; this is the fundamental notion of causality in distributed computing.
causalpending
Speaker
Leslie LamportEvidence Quote
“the notion of happens before is exactly the same as in relativity except instead of being whether something one event can influence another by things traveling at the speed of light, it's whether the first event could have affected the other by information sent over messages that were actually sent in the system.”
Source
Turing Award Winner: Thinking Clearly, Paxos vs Raft, Working With Dijkstra | Leslie Lamport— Ryan PetermanCreated: 8/12/2026, 6:17:50 PM
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