I'll chime in here that Merkle trees are best used to tell you if something changed in the historical records. Certificate Transparency (CT) provides you with a

I'll chime in here that Merkle trees are best used to tell you if something changed in the historical records. Certificate Transparency (CT) provides you with an easy to verify way to generate a single identifier that tells you the current state of a set of information. You can then incrementally add onto it while checking that none of the past information was changed during that addition. This is a pretty similar concept (and motivation) to Git. Where this becomes interesting is that someone can just change the past data, then go through and update all the subsequent additions to come up with a the new final value. CT handles this by having multiple other entities check that the CT root values are not changing over time. Git handles this by allowing for similar mechanisms - if you believe Linus he memorizes the root hash of his local repo before bed each night. A post-it note would work just about as well for the Linus/Git case, but I am getting off topic. I don't see value in proof of work because it assumes that any system would have more entities (where each entity has some amount of computing power..) watching than there is computing power attempting to rewrite it. That doesn't really scale up across most industries use cases. A set of say, mortgage companies, could just exchange data in a merkle tree format and raise an alarm if it looks like the values changed from the prior root. This is very fast and cheap to compute and doesn't require proof of work calculations.