Hal Finney to Satoshi with foundational scalability questions during pre-release review (November 19, 2008)

This email was sent during the pre-release code review period, approximately two months before Bitcoin’s public launch. Finney had been reviewing Satoshi’s code and draft paper. His email, a reply under the subject “Re: Bitcoin source files attached” with Ray Dillinger and James A. Donald on Cc, asked fundamental scalability questions:

How large do you envision it becoming? Tens of nodes? Thousands? Millions?

He also asked:

And for clients, do you think this could scale to be usable for close to 100% of world financial transactions?

These questions demonstrate that Finney — a veteran cryptographer who had worked on PGP and created the first reusable proof-of-work system (RPOW) — was thinking seriously about Bitcoin’s potential from the very beginning. While most recipients of the whitepaper on the Cryptography mailing list were skeptical, Finney was one of the few who engaged deeply with the technical details.

This email was published by CoinDesk on November 26, 2020, based on files from Hal Finney’s personal computer that his widow Fran Finney provided to journalist Nathaniel Popper (author of Digital Gold) in March 2014. It is the first of three emails in the archive’s hub entry for that disclosure. The second, Satoshi’s January 8, 2009 v0.1 release notice to Finney, is the direct continuation of this same pre-release correspondence.