It's called the oracle problem, and was identified for blockchain apps as early as 2011. It's a difficult problem to solve, but it is solvable for certain appli

It's called the oracle problem, and was identified for blockchain apps as early as 2011. It's a difficult problem to solve, but it is solvable for certain applications. For example, MakerDAO solves their price oracle problem by using a set of whitelisted ETH/USD price API's. The whitelist is controlled via governance through the MKR token.