I understand that currently the PoW chain and the beacon chain are both executing simultaneously as two (basically) distinct blockchains.

I also understand that after the merge the beacon chain will be responsible for the consensus and there will be no more PoW.

So given that the PoW chain is much older and longer than the beacon chain, how will block height work after the merge? Will it continue from the current PoW height? And if so will there be a bunch of skipped heights when looking at the beacon chain? Or will it continue from the current beacon chain height? I guess not because then the same block numbers already exist in the PoW chain.

And related, if I want to sync a brand new node from scratch after the merge, will I sync the history of the PoW chain, or the beacon chain, or both?

2 Answers 2


Ethereum 2.0 progresses in epochs, not blocks. An epoch is a bundle of up to 32 blocks that validators propose and attest over a period of approximately 6.4 minutes. An epoch and all the blocks it's composed of is only finalized after two more epochs have passed.

See: https://www.coindesk.com/tech/2021/01/08/ethereum-20-explained-in-4-easy-metrics/


We can see using an explorer like Etherscan, that block heights / blocknumbers continued from the PoW height.

The beacon chain has its own explorers, blocknumbers, and APIs to get such data. For a given block, Etherscan also shows the corresponding slot and epoch.

For syncing, you will need both a consensus layer client and an execution layer client.

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