Quote from: MysteryMiner on October 21, 2012, 05:45:11 AM

Quote from: gmaxwell on October 21, 2012, 04:51:58 AM

Quote from: MysteryMiner on October 21, 2012, 04:21:50 AM

(but this did not prevent some well meaning halfbrains from sending additional coins to that address).

_Those_ coins, however, are spendable.

Does not they have been "fused" to 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa address and is spendable only with private key matching this receiving address? And since none can send 51 BTC (coinbase + Your "spendable" coins) out of this address they all are lost?

The reason why the genesis block mining reward transaction can not be spent is because the reference bitcoin client doesn't add it to the list of known transactions at startup. If it were a normal block that would happen, but it's not a normal block and doesn't get loaded like a normal block would. Thus any attempt to spend it will look like someone is attempting to spend a transaction that was never made in the first place.

Spending subsequent transactions to the address the genesis transaction was made to is possible because those transactions are normal transactions that every bitcoin client knows about.

Remember that a transaction is basically a message stating that coins from one or more prior transactions are now spendable by whoever has the private keys to one or more public keys. (vastly simplifying here) Transactions to the destination address of the genesis block transaction simply state that whoever can sign messages with the public key "satoshi's genesis block key" is allowed to spend the transaction. The fact that the genesis block transaction itself is unspendable is irrelevant, and only an artifact of it not going into every nodes pool of known transactions.

In short, in Bitcoin every transaction is completely independent. All this stuff about addresses is just a convenience that the client calculates for you based on what public keys are designated as able to spend a given transaction.