If transactions are less than 176 bytes on average, the central database can handle 710,000 transactions per second on a standard Gigabit network. Centralized databases also use distributed system technology known as optimistic concurrency control to replicate and maintain high availability without significantly compromising transaction rates. [HTKung, JTRobinson (1981)] In Solana, we show that these same theoretical limitations apply to blockchains in hostile networks. What's the core ingredient? Find a way to share time when nodes cannot depend on each other. When nodes become time-dependent, 40 years of distributed system research will suddenly be applied to the blockchain!