Unbreaking testnet4

In the recent discussion among Bitcoin developers, a proposal has been put forward to modify the current block time from 10 minutes to a more extended period of 20 minutes. This change aims to address several issues inherent in the Bitcoin mining process, particularly concerning the validation and rejection of blocks mined by different types of hardware. The adoption of a 20-minute block time, coupled with a rule that deems any block exceeding this duration invalid (with exceptions during difficulty adjustments), is suggested as a means to accurately reflect the 'real value' of mining difficulty.

The argument supporting this adjustment hinges on the observation that CPU-mined blocks, despite their potential vulnerability to reorganization (reorg) by miners controlling a majority of the network's hash rate, should still be recognized by the network's nodes. This approach would ensure that blocks mined using CPUs remain valid and enforceable, especially since these blocks could otherwise be quickly invalidated by those produced through more powerful ASIC mining rigs. The suggestion implicitly acknowledges the significant disparity in computational power between CPU and ASIC mining, proposing a mechanism to mitigate its impact on the network's decentralization and security.

Furthermore, the proposal includes a method for enhancing time synchronization across the network. By embedding the 'real time' within block headers during the bi-weekly difficulty adjustment, it ensures that all network participants maintain an accurate and unified sense of time. This could potentially streamline various aspects of network operation and security, particularly in how nodes assess and integrate newly mined blocks.

Another facet of the discussion revolves around how nodes can selectively recognize blocks mined by specific hardware types, such as ASICs, to avoid being overwhelmed by blocks mined by less powerful CPUs. This selective recognition could allow node operators to prioritize stability and reliability in their operations, given the vast difference in the ability of ASIC versus CPU miners to produce blocks that stand a lower chance of being reorganized.

Overall, the proposal to extend Bitcoin's block time to 20 minutes seeks to balance the scales between different mining practices, improve network synchronicity, and offer node operators more control over the blocks they choose to acknowledge. This initiative reflects ongoing efforts within the Bitcoin development community to adapt and refine the cryptocurrency's underlying technology in response to evolving challenges and opportunities.