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Basic mining question:

Once a miner solves the block and comes up with the block hash, how are the other nodes in the network incentivized to validate that hash?

marked as duplicate by dark knight, Andrew Chow Nov 24 '17 at 23:45

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  • Well, what do you mean exactly? You say "validate that hash" but do you mean validate that the new block satisfies the PoW requirement (meets the difficulty)? Or do you mean validate all the transactions in the new block as well as the block header itself? Or what? – Fraggle Nov 24 '17 at 12:20

If they wouldn't validate it, they aren't participating in Bitcoin anymore, i.e. they wouldn't see new payments confirm.


Determining the correct composition of the block, including what nonce to use, and what transactions to include is the difficult work in mining. Verification of a mined block is non-compute-intensive, and since the hash of the most recent block is required as an input to the next block, it must be validated prior to searching for the next block. Therefore, if you want to mine for a block, you must validate the prior block's hash.


I think you mean to ask "Why would any miner validate someone else's block? Why wouldn't they just keep mining and try to find that new block themselves, and thus get the reward?"

The answer is that any miner should always assume that every other miner in the network will accept any valid block, because not doing so could leave a miner behind in the longest-POW-chain. Once behind, a miner will never catch up to the network (unless they have more than 50% of the hashpower), so all miners are incentivized to mine on top of the current longest valid chain they know of.

Nodes will understand this behaviour, and similarly always follow the longest-POW-chain, so that they will stay in sync with the network.

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