Satoshi Nakamoto: Who Invented Bitcoin?

On October 31, 2008, an email landed on a mailing list for cryptographers and privacy advocates. The sender called himself Satoshi Nakamoto, and nobody knew who that was. It linked to a nine-page paper titled Bitcoin: A Peer-to-Peer Electronic Cash System. His first sentence was plain: 'I've been working on a new electronic cash system that's fully peer-to-peer, with no trusted third party.' Digital money had one big problem, called double-spending. A file can be copied, so what stops someone from spending the same coin twice? Banks solved it by keeping the books themselves. Satoshi proposed a shared public ledger, a chain of blocks now known as the blockchain, that records every transaction in a fixed order. Proof replaced trust, and no bank or central authority was needed. But the man who wrote it did not stay around. Who was Satoshi Nakamoto, and where did he go?