Here is a thought for those who think the bitcoin blockchain should be used for all kinds of notary stuff.
To guarantee the timestamp and the integrity of documents, only a single miner would be needed, which in that case would not need to expend energy, just create the blocks in a timely manner. Why is this enough? Because the whole chain is known at all times, and to cheat, the miner has to unwind the chain down to the document he wants to tamper with, and recreate the rest of the chain. This will then be obvious to all.
not sure what you're trying to get at but that would be totally unworkable. that sole miner would have 100% of the consensus which would allow unfettered rewriting of the entire BC if he so wished. the community has to prevent any such tampering and the only way to do that is to distribute the ledger across space and across many different miners to enforce against that type of cheating.
