You can't unilaterally upgrade bitcoin?<p>what purpose would there be in making it a fork of bitcoin?<p>Ethereum uses an addresses system, which is kinda needed for the smart contract system, while bitcoin uses an unspent outputs system.<p>Also, the proof of work system is rather different, and the block times are shorter.<p>To make it a fork of bitcoin instead of having its own genesis block and all, would require a bunch of extra work without providing much benefit.<p>Why would it be a change to bitcoin?