← Course contentsLesson 1 of 8

Origins and the Problem Being Solved

Where Bitcoin and Ethereum came from, what problem each was built to solve, and why the pieces existed for decades before anyone assembled them.

Bitcoin was assembled, not invented

Every component of Bitcoin existed before 2008. Satoshi Nakamoto's contribution was the assembly and one new rule.

YearContributionWho
1980–1982The Byzantine Generals Problem — how nodes agree when some lie or go silentLamport, Shostak, Pease
1991Cryptographic timestamps — documents chained by hash so order cannot be rewrittenHaber, Stornetta
1997–2002Hashcash — spend compute, prove effort; an anti-spam mechanismAdam Back
2001SHA-256 standardisedNSA / NIST
2008The Bitcoin whitepaper — the longest chain rule, combining all of the aboveSatoshi Nakamoto
2009Genesis block, mined 3 January

The genuinely new part is the longest-chain rule: a way to select one history from many competing ones without asking anybody's permission or identity.

The problem, stated in the whitepaper

The 2008 paper is unusually direct about what is wrong:

  • Online payments run through banks as trusted middlemen.
  • Because payments can be reversed, disputes must be mediated.
  • Mediation raises costs, which kills small, casual payments.
  • Merchants respond by demanding more information than they need, and simply accept a certain amount of fraud as a cost of doing business.

The insight: replace trust with cryptographic proof, so any two willing parties can transact directly. The solution: electronic cash sent peer to peer, with double-spending prevented by a proof-of-work chain that acts as a timeline everybody agrees on.

The Byzantine Generals Problem

Several generals surround a city. They must agree on one plan. But:

  • Some lie — traitors send false orders.
  • Some go silent — messages never arrive.
  • Some arrive late — the network is not instant.

Mapped onto Bitcoin: each general is a node, each message is a transaction, and the plan they must all agree on is the order of the blocks. This is why the problem matters — ordering, not arithmetic, is the hard part of a distributed ledger.

Ethereum's separate origin

Ethereum did not fork Bitcoin's goal. It asked a different question: if a network can agree without a middleman, what else could it run?

YearEvent
2011–2012Vitalik Buterin helps found Bitcoin Magazine; sees Bitcoin's potential and its limits
Nov 2013Ethereum whitepaper — a blockchain that runs smart contracts, not just payments
2014Gavin Wood's Yellow Paper (the EVM spec); crowdsale raises ~31,000 BTC
Jul 30 2015Frontier — the genesis block is mined and the network goes live

Bitcoin optimises for being one thing that cannot be changed. Ethereum optimises for being a machine that runs whatever anyone deploys. Almost every later difference follows from that split.