Bitcoin miners at large have missed the first BIP 148 “deadline” to prevent a “split” in Bitcoin’s blockchain.
As Bitcoin’s scaling dispute appears to be heading for a climax, the next couple of weeks could prove pivotal. One scaling solution in particular, Bitcoin Improvement Proposal 148 (“BIP 148”), is scheduled to trigger activation of Segregated Witness (SegWit) on August 1, 00:00 UTC. As a User Activated Soft Fork (UASF), all users that run a BIP 148 node will then start rejecting any and all blocks that do not signal support for SegWit by the “deadline” — or, perhaps more accurately, “ultimatum” — set by BIP 148 users.
BIP 148 and SegWit are backward-compatible protocol upgrades, which means that non-upgraded nodes will still accept SegWit-signaling and SegWit-utilizing blocks. Therefore, if a majority of hash power in one way or another adopts SegWit before August 1, all current Bitcoin nodes would follow the same blockchain.
However, if only a minority of miners activates SegWit through BIP 148, Bitcoin’s blockchain and currency would “split” in two. This would result in two types of “Bitcoin”: one that activated BIP 148 and one that did not, while even more types of “Bitcoin” could emerge as a result. A split between BIP148-nodes and non-BIP148 nodes would last at least until a majority of hash power joins the BIP 148 chain, or until the BIP 148 chain is abandoned by all users and miners for good.
Miners essentially have three options to avoid such a split. This first option was to lock in SegWit before August 1 through the activation mechanism proposed by Bitcoin Core and implemented in many nodes on the network. This required 95 percent of hash power to signal support for the upgrade within a two-week difficulty period. Specifically, such a difficulty period consists of 2,016 of these sequential blocks, which means that a minimum of 1,916 blocks must signal support. Or, in other words, if more than 100 blocks ...