If the current Bitcoin miners lose 99.99% of their hash rate, mining the next block would take a lot more than the average set of 6 per hour (10 minutes). Is the mining difficulty somehow readjusted in order to face this potential problem?



According to the Bitcoin Wiki, the difficulty is only adjusted every 2016 blocks.

The difficulty of the mathematical problem is automatically adjusted by the network, such that it targets a goal of solving an average of 6 blocks per hour. Every 2016 blocks (solved in about two weeks), all Bitcoin clients compare the actual number created with this goal and modify the target by the percentage that it varied. The network comes to a consensus and automatically increases (or decreases) the difficulty of generating blocks.

However, Bitcoin Cash has a solution to the problem.

If less than 6 blocks have been mined in the past 12 hours. It becomes 20% easier to mine blocks.

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  • The only reason that BCH needed the faster difficulty adjustment was to ensure survival when nobody knew how many miners would switch to BCH at the time of the fork. A fast difficulty adjustment is not needed for a healthy network, it's not a "problem" that needs solving. – Greg Hewgill Sep 21 '17 at 0:20
  • Can we expect BCH to drop the feature? – Cedric Martens Sep 21 '17 at 0:50
  • No, because that would be another hard fork. The feature pretty much has to be there forever, unless you can get all BCH users to agree to drop it. – Greg Hewgill Sep 21 '17 at 0:51
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    To clarify a little, in Bitcoin cash, difficulty is not adjusted at the 12th hour, but at the 6th block after 12 hours. – sanket1729 Sep 21 '17 at 2:17

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