> any use of blockchain technology in which the ledger is not self-contained [is unusable because] there can be no trust-free link between the ledger and the ph

> any use of blockchain technology in which the ledger is not self-contained [is unusable because] there can be no trust-free link between the ledger and the physical world. Sure, data would need to be verified by a trusted party when it's first entered. A blockchain still protects against forgery after this though.