Mining their own business

摘要

WHEN GOLD prices fall, precious-metals firms suspend exploration and close mines with high operating costs. In theory, bitcoin miners should act similarly. Although bitcoin is a virtual currency, it is expensive to obtain. To "mine" new bit-coins-ones that do not already belong to someone else-users hook up their computers to a network, and instruct them to keep guessing the solution to a maths problem until they get it right.