Solana · 2017–2018
Anatoly Yakovenko’s clock for strangers
Solana’s early design began with a problem familiar to anyone comparing logs from two different machines.
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Two computers can receive the same messages in opposite orders. Each can report its own observations honestly. If the messages are competing instructions to spend the same balance, however, a network needs an agreed sequence before it can apply them. In the early Solana white paper, Anatoly Yakovenko treated that sequencing problem as a design question of its own.
His proposal, Proof of History, uses a calculation in which each output becomes an input to the next step. Data can be mixed into the sequence as it runs. Think of receiving a receipt that appears between two numbered marks in a long calculation: another machine can check the sequence and the position of the receipt without trusting the clock displayed on the sender’s screen.
There is a limit to what that receipt establishes. It gives evidence of order within one sequence. Validators still need rules for deciding which history to accept, and a position in the sequence cannot make an invalid payment valid. That distinction explains why Yakovenko devoted so much of a blockchain paper to a clock. He was isolating one job that every participant would otherwise have to coordinate.