Revision · Bitcoin in Context

This part compared Bitcoin, Ethereum, and Solana from first principles, asking one engineering question of every design: what problem is it solving, and what does that solution cost? The fastest way to understand Bitcoin is to study systems that made the opposite choice.

What this part covered

• UTXO vs the account model — Bitcoin tracks a stateless pile of unspent coins while Ethereum keeps one global, always-mutating map of balances, nonces, and contract state; the choice shapes parallelism, privacy, and how “balance” even works.
• Smart contracts & the EVM — the EVM is a Turing-complete 256-bit stack machine that runs what Bitcoin Script deliberately won’t, and gas turns the halting problem into an economic one by metering every operation.
• Proof of Stake & The Merge — Ethereum swapped scarce energy for scarce capital on 15 September 2022, replacing miners with validators whose staked funds can be slashed, alongside an honest debate about the resulting security model.
• Solana’s architecture — still Proof of Stake with a clock bolted on: Proof of History as a verifiable clock, Sealevel for parallel execution, and Gulf Stream for forwarding transactions, bought at the cost of hardware centralization and real outages.
• Fees, throughput & blockspace — every chain sells the same scarce thing (space in the next block), but Bitcoin’s pure vbyte auction, Ethereum’s EIP-1559 base fee, and Solana’s near-zero local fee markets price it very differently.
• The 2024 cycle — the era’s defining events read through this lens: US spot ETFs in January 2024, the fourth halving at block 840,000, and Runes launching at that halving.
• The L2 & scaling frontier — the shared answer to “the base layer can’t do everything” is to keep verification on L1 and push execution off it, via rollups, sidechains, and Lightning.
• Why three chains exist — the trilemma means you can’t max soundness, programmability, and throughput at once, so BTC optimizes for trustless soundness, ETH for programmability, and SOL for throughput.

The takeaway

Marketing compares chains by feature lists, but the causes are a handful of foundational dials: state model, script power, Sybil cost, node requirements, and block cadence. Set them one way and you get Bitcoin’s credible neutrality; set them another and you get Ethereum’s expressiveness or Solana’s speed — each a real win paid for somewhere less obvious. With that comparison in hand, the book turns hands-on and then to building a chain from scratch.