Over the last ten years, we’ve seen blockchain-based cryptocurrencies consistently prove themselves a reliable means of settlement, and indeed, we believe that cryptocurrencies are the inevitable evolution of payments. But today’s merchants operate in a fiat world—with fiat costs and margins. If we want to enable merchants to receive payment in local fiat while their customers pay using cryptocurrencies, we need a solution for the problem of decentralized consensus (and specifically, the fact that no consumer is going to wait thirty minutes in the checkout line for the merchant’s required blockchain confirmations before they walk out of the store with their purchase). ...