Blockchain technology is going to change everything: the shipping industry, the financial system, government … in fact, what won’t it change? But enthusiasm for it mainly stems from a lack of knowledge and understanding. The blockchain is a solution in search of a problem.
It doesn’t try to replace trust with computation, which is a crucial difference.
what do you mean by that?
Nothing in Git requires reversing hashes (which requires a lot of computing power), there’s only forward computation (much cheaper), and there isn’t any other method of establishing global consensus either (like proof of stake). This means no one needs an expensive rig to create git commits and fork whole repos, but on the other hand the hashes only prove the integrity of one set of commits; there is no global consensus on any repo and there has to be some sort of access control to prevent someone from force-pushing or replacing whole histories, central maintainers to decide what gets merged, etc. At best, to check if the upstream did something fishy, a mirror can be compared to another, or to a local copy.
edit: or perhaps, it wouldn’t be technically incorrect to call a git repo a blockchain, as the distributed global consensus without human maintainers may not be part of the strict definition, but this seems pretty anachronistic and pointlessly confusing to me.
Yes, it doesn’t have any method for distributed global consensus. Instead, everyone gets to decide what they think the “tip” should be. Signed commits can give you insight into what others think it should be, though.
If I fork bitcoin and and replace proof-of-work with signed blocks, I would argue that its still a blockchain, just not decentralized. This would still be useful because others could see if I tried to re-write history.
I think of a blockchain, simply as a chain of blocks where each block contains a hash of its contents + the previous blocks hash. So, their primary feature is being an append-only tamper-evident database.