ah, i understand your question better now. how does it anchor to an external clock? i think it’s by consensus of everyone choosing their own clock, but i don’t know a ton of detail about it. i found this

“For reasons of stability and low latency in transactions, the network tries to produce one block every 10 minutes. Every 2016 blocks (which should take two weeks if this goal is kept perfectly), every Bitcoin client compares the actual time it took to generate these blocks with the two week goal and modifies the target by the percentage difference.”