Bitcoin’s ledger is a chain of blocks, each one a batch of transactions added by miners, firms running warehouses of specialised computers that compete to produce the next one. They are paid in newly issued bitcoin plus the fees attached to those transactions, and a block arrives roughly every ten minutes.
That ten-minute pace is not automatic. The network sets a difficulty level, which is how much computing work a miner must do to produce a valid block, and recalculates it every 2,016 blocks. If blocks have been arriving too fast, the work gets harder. Too slow, and it gets easier.
At normal speed, 2,016 blocks takes about two weeks.
Two blocks were produced on that chain. Then it stopped, because mining it costs exactly what mining bitcoin costs — as both chains having inherited the same difficulty when they parted, while paying in a coin that…
