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When will a discernible, coordinated Bitcoin mining pool attain >=50% of the hashing power for 24-hours, before Sep 15 2025?
51% attacks are an important vulnerability of proof-of-work blockchains.
In 2014, Ghash.io gained more than 50% of the hashing power in Bitcoin’s mining network, which could have resulted in a 51% attack. Ghash instead voluntarily reduced their hashing power to below 40%. No mining pool has been above 50% of hashing power since then, although 51% attacks have been successfully conducted on blockchains with vastly smaller hash rates, such as Ethereum Classic (ETC).
On what date will a discernible, coordinated Bitcoin mining pool attain >=50% of the hashing power for any 24-hour period before Sep 15, 2025?
The reported >=50% hash rate event can be reported as having taken place during any 24-hour period, and is not timezone-dependent.
If the question does not resolve positively by Sep 15 2025, the question resolves as > Sep 15, 2025.
The "mining pool" could either be a shared pool among unassociated miners, or a massive operation by a single entity.
Note that in hash rate distribution charts, "Unknown" does not necessarily mean a single unidentified mining pool is taking up that much hash rate, but simply that they aren't identified. To count for resolution, a pool must be discernibly combining their hash rate. If the hash rate from "Unknown" miners ever attained >=50% of the hash rate, but there were no reports to suggest a coordinated mining operation was taking up >=50% of the hash rate, then that does not count to positive resolution.
One possible scenario is an identified miner openly mining the blocks and processing transactions like normal but with >50% the hashrate. Another (perhaps more likely) is a separate chain being mined in secret with >50% hashrate, until that alternative chain becomes bigger than the main one, causing a deep block reorg that had its hashrate come entirely from that secret miner. If this kind of secret-miner reorg happens, and it’s more than roughly 72 blocks deep, it could trigger positive resolution instantly, since that would tend to be be more than 12 hours worth of the blockchain, and it would've all been from one miner.
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