Full disclaimer: I work for Vitalik and the Ethereum Research Team.
Here are a couple of reasons for why we are ultimately eschewing PoW:
(1) We are pushing to get blockchain updating down to 3 seconds. You really can’t do this with PoW, since 3 seconds is our budget for our network overhead.
(2) A single block chain doesn’t scale well—we’re pushing for protocols that involve multiple blockchains processing transactions independently. The current proposals all rely essentially on PoS based on the central Ethereum Blockchain. Proof of Work isn’t generally secure for these architectures—if a new blockchain was created then a botnet could easily gain 51% of the compute power for a while before hashing power could be directed from other parts of the network.
Full disclaimer: I work for Vitalik and the Ethereum Research Team.
Here are a couple of reasons for why we are ultimately eschewing PoW:
(1) We are pushing to get blockchain updating down to 3 seconds. You really can’t do this with PoW, since 3 seconds is our budget for our network overhead.
(2) A single block chain doesn’t scale well—we’re pushing for protocols that involve multiple blockchains processing transactions independently. The current proposals all rely essentially on PoS based on the central Ethereum Blockchain. Proof of Work isn’t generally secure for these architectures—if a new blockchain was created then a botnet could easily gain 51% of the compute power for a while before hashing power could be directed from other parts of the network.