Even though Ethereum does not directly use GHOST, stale blocks can be included as uncles for a reward.

How can uncle blocks remain valid, as I suppose state transitions must be non-conflicting? The design rationale says that these "uncles have to be valid headers, not valid blocks" yet they could be.

I suppose if there is a single interaction with the same element in the state trie of e.g uncle block U and current child C and/or parent A, then U cannot be valid anymore. Which I would assume happens quite often now with AMM pools and complex, composable transactions.

So is it correct to assume that most uncles receive a reward, but they do not change the actual state of the longest chain?

1 Answer 1


Yes, uncle block's transactions are ignored and they do not alter the Ethereum world state. The only effect is to the involved miners when their rewards are credited.

  • Is it too complex to include blocks that do not have conflicting transactions? I believe it would scale Ethereum, as these blocks are still wasted now.
    – Marcellvs
    May 4, 2021 at 13:46
  • @Marcellvs You would have to merge the resulting world states, it will be equivalent to having one block with double size. It may help scaling in one aspect but it might cause other issues, time processing some blocks will double.
    – Ismael
    May 5, 2021 at 1:35
  • Yeah I assume merging the states is near impossible.
    – Marcellvs
    May 5, 2021 at 21:27
  • @Marcellvs I don't think it is difficult, but you will not gain much in scalability for it to be worth.
    – Ismael
    May 6, 2021 at 2:30

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