I'm almost certain this comment won't be met with much support (so I apologize in advance) but I've been thinking a lot about decentralized clock synchronization while helping to write the FOAM whitepaper. It's probably well known within the #scuttleverse that ssb implements a completely subjective view of the network, down to the ordering of events, which I think is one of ssb's most interesting features. Proof of work blockchains choose the exact opposite approach, complete state replication and an objective, totally ordered clock. I'm wondering if ssb might want to make this choice explicit by allowing users to chose which clocks they trust. This could be the personal clocks of other users, or an external proof of work clock. The latter which would be accomplished by inserting the the most recent block hash into ssb's message header. Each user would then have the ability to set the precedence of different clocks. I think this is more of a thought experiment than an actual suggestion, but I like the idea of letting users choose how they relate to time.