Class-25

Class 25 – Ethereum 2.O Explainer, Phases, PoS & Serenity

Class Slides: Class 25.1

This lecture explores the core concepts of Ethereum 2.0’s upgrade from Proof of Work (PoW) to Proof of Stake (PoS), focusing on scalability solutions like sharding, the role of validators, and the structure of phases in Ethereum’s consensus layer evolution.

Key Topics Covered:

1. Sharding Overview
Sharding is a solution designed to improve Ethereum’s scalability by dividing the blockchain into smaller units called “shards.”

• Each shard operates like a mini-blockchain and can process its own set of transactions and smart contracts independently.

• Shards work in parallel, allowing for significantly higher transaction throughput.

• Cross-shard communication is enabled to maintain integrity and synchronization across the network.

Benefits:

• Increased scalability

• Lower transaction fees

• Reduced network latency

• Improved energy efficiency

2. Transaction Execution in PoS
Transactions in Ethereum 2.0 follow a validator-based process:

• One validator is chosen as a block proposer per slot (12 seconds).

• The block proposer gathers transactions, executes them, and packages them into a block.

• Other validators in a committee attest to the block, confirming its validity.

3. Ethereum 2.0 Phases
Ethereum 2.0 is introduced in multiple phases for smoother transition and upgrade:

• Phase 0 – Beacon Chain: Implements the PoS mechanism and introduces validators.

• Phase 1 – Shard Chains: Introduces shards primarily for data storage.

• Phase 1.5 – The Merge: Ethereum 1.0 merges into Ethereum 2.0 as a shard, transitioning the mainnet to PoS.

• Phase 2 – Full Sharding: Enables smart contract execution on shard chains with full functionality.

4. Slots and Epochs
Time is structured into slots (12 seconds each) and epochs (32 slots = ~6.4 minutes).

• Validators are shuffled and assigned to committees per epoch.

• Blocks are proposed and attested within these intervals to maintain the network’s rhythm and finality.

5. Validators and Attestations
Validators replace miners under PoS:

• Require a deposit of 32 ETH to participate.

• Responsible for proposing blocks and attesting to others.

• Validators earn rewards for honest behavior and are penalized or slashed for malicious actions or inactivity.

• Attestations serve as votes for block validity and are essential for reaching consensus.

This lecture emphasizes the transformational structure of Ethereum 2.0, introducing key components like sharding for scalability and validators for energy-efficient consensus. By organizing time and validator responsibilities through slots, epochs, and committees, Ethereum 2.0 enhances its performance, decentralization, and security.