Bridges & Layer 2s
Blockchains are notoriously slow and isolated. To scale purely digital economies to billions of users, we need Layer 2s for speed and Bridges for connectivity.
The Scalability Problem
The Blockchain Trilemma states that a chain can only optimize for two of three properties: Decentralization, Security, and Scalability.
Anyone can run a node. No single point of control.
The cost to attack the network is prohibitively high.
The ability to process thousands of transactions per second (TPS). This is where L1s fail.
Ethereum L1 prioritizes Decentralization and Security. It charges high fees because block space is scarce. To solve this, we move execution off-chain.
Layer 2: Rollups
A Rollup is a separate blockchain that executes transactions outside of Ethereum but posts the transaction data (or proof) back to the L1. This inherits the security of Ethereum while splitting the gas costs among thousands of users.
The "Court" Analogy
Slow, expensive, and final. It doesn't want to hear every speeding ticket case. It only settles disputes and finalizes history.
Fast and cheap. Handles 99% of the day-to-day transactions. Only goes to the Supreme Court (L1) if absolutely necessary.
Two Types of Rollups
Optimistic Rollups
Philosophy: "Innocent until proven guilty."
They assume all transactions are valid. Transactions are posted to L1 immediately, but there is a 7-day challenge period where anyone can submit a "Fraud Proof" if they spot cheating.
ZK-Rollups
Philosophy: "Don't trust, verify."
They generate a complex Zero-Knowledge Proof for every batch. The L1 contract verifies the math instantly. No waiting period, but computing the proof is computationally expensive.
Bridges: Breaking the Silos
Blockchains are disjointed databases. Bitcoin does not know Ethereum status; Ethereum does not know Solana status. Bridges are the infrastructure that connect these isolated networks.
Mechanism 1: Lock-and-Mint
This is the most common method for moving assets (e.g., getting BTC onto Ethereum as WBTC).
- You lock Asset A in a smart contract on the source chain.
- The bridge observers verify this event.
- The bridge mints an equivalent amount of Wrapped Asset A on the destination chain.
- To return, you burn the wrapped asset, and the smart contract unlocks the original.
Mechanism 2: Liquidity Pools
Instead of wrapping, the bridge keeps pools of assets on both chains. You deposit USDC on Chain A, and the bridge releases USDC to you from its pool on Chain B. This requires the bridge to have deep liquidity on both sides.
Critical Risks
The Honey Pot Problem
Bridges secure billions of dollars in "locked" assets. This makes them the #1 target for hackers. If the locking contract on the source chain is exploited and drained, the "wrapped" tokens on the destination chain become worthless immediately.
Sequencer Centralization
Most Flight L2s rely on a single server (the Sequencer) to order transactions. If it goes down, the chain halts. While they cannot steal funds (due to L1 settlement), they can censor transactions or cause downtime.
The Multi-Chain Future
The end goal is Chain Abstraction. Users shouldn't need to know whether they are on Base, Arbitrum, or Ethereum. Wallets and apps will handle the bridging and switching automatically in the background, creating a seamless "Superchain" experience.
Frequently Asked Questions
If an L2 goes down, are my funds lost?▼
No. If it is a true Rollup (and not a sidechain), usage of the "Escape Hatch" allows you to prove ownership via Ethereum L1 and withdraw your funds directly from the smart contract, even if the L2 sequencer is completely offline.
Why do Optimistic Rollups wait 7 days?▼
This window is necessary to allow verifiers to detect fraud and submit a proof. If withdrawals were instant, a malicious sequencer could steal all funds before anyone noticed. "Fast Exit" bridges exist by lending you liquidity upfront for a small fee.
Are Bridges safe?▼
They are historically the weakest link. Most "hacks" in crypto are bridge exploits (e.g., Ronin, Wormhole). Trustless bridges (Rollups) are safer than multisig bridges, but any code moving billions of dollars is a high-value target.