Unit 2 · Level 2 · The scaling problem
Paths to scale
If bigger blocks alone won't do it, what will? Three broad paths emerged. One: build a beefier L1 that demands more from its nodes (Solana's route). Two: keep the base chain lean and push activity to layers built on top, called L2s (Ethereum's route). Three: give each application its own purpose-built chain, an app-chain (the Cosmos philosophy). None of them escapes the trilemma; each just picks a different place to pay.
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What you get asked
Match each scaling path to its core idea
Four answers to one question: where should the work happen? Everything in the next two units is a variation on these.
Which path did Ethereum choose for scaling?
Ethereum's 'rollup-centric roadmap': the base layer stays easy to verify, while layers on top compete to make transactions cheap.
What's the honest tradeoff of building your app its own chain?
An app-chain sets its own rules and captures its own fees, but it must recruit its own validators, and a chain is only as strong as what defends it.
A rollup executes transactions elsewhere but ___ on the L1.
Execution moves upstairs; the final record and its security stay anchored to the base chain. That split is the heart of unit 3.
What do all three scaling paths have in common?
Heavier nodes, new trust assumptions, or fragmented security: every road out of the jam has a toll booth. The skill is knowing which toll you're paying. 🐜
The rest of this unit
Why block space is scarce, and why 'just make blocks bigger' started a war.