What is Merge? How does it move Ethereum from PoW to PoS?

The Ethereum Merge transitioned the network from energy-intensive Proof-of-Work to a more efficient Proof-of-Stake system, merging the execution and Beacon Chain layers to reduce energy consumption and improve scalability.

Mar 06, 2025 at 08:18 am

Key Points:

• The Merge is the upgrade that transitioned Ethereum from a Proof-of-Work (PoW) consensus mechanism to a Proof-of-Stake (PoS) consensus mechanism.
• This transition aimed to significantly reduce Ethereum's energy consumption and improve scalability.
• The Merge involved merging the existing Ethereum mainnet (execution layer) with the Beacon Chain (consensus layer).
• The process involved a complex series of steps and upgrades leading up to the final merge event.
• Post-Merge, Ethereum miners became validators, requiring staked ETH to participate in consensus.

What is the Merge?

The Merge was a highly anticipated upgrade to the Ethereum network. It marked a fundamental shift in how the network validates transactions and reaches consensus on the blockchain's state. Before the Merge, Ethereum used a Proof-of-Work (PoW) system, similar to Bitcoin, requiring energy-intensive mining to secure the network. The Merge transitioned Ethereum to a Proof-of-Stake (PoS) system, dramatically reducing its energy footprint and paving the way for future scalability improvements. This wasn't a single event but a culmination of several upgrades.

How did the Merge move Ethereum from PoW to PoS?

The transition wasn't a simple switch. It involved a complex process of merging two separate components of the Ethereum network: the execution layer and the consensus layer.

• The Execution Layer: This is the part of Ethereum that processes transactions and executes smart contracts. This remained largely unchanged during the Merge. It's what users interact with directly.
• The Consensus Layer (Beacon Chain): This is a separate blockchain introduced in 2020 that uses a PoS mechanism. The Beacon Chain was responsible for validating transactions and proposing blocks. The Merge essentially joined this with the existing execution layer.

The Merge itself involved several steps:

• Beacon Chain Launch: The first step was launching the Beacon Chain, a separate PoS blockchain running in parallel to the existing PoW mainnet.
• Client Upgrades: Software clients used to run Ethereum nodes needed updates to support the Merge. This required coordination among developers and node operators.
• The Terminal Total Difficulty (TTD): The Merge was triggered when the Ethereum PoW blockchain reached a predetermined total difficulty (TTD). This ensured a smooth transition and prevented potential issues.
• Finalization: Once the TTD was reached, the execution layer switched to using the Beacon Chain for consensus. PoW mining effectively ceased, and the network transitioned fully to PoS.

Proof-of-Work (PoW) vs. Proof-of-Stake (PoS):

PoW relies on miners competing to solve complex cryptographic puzzles to validate transactions and add new blocks to the blockchain. This process consumes significant energy. PoS, in contrast, selects validators to propose and verify blocks based on the amount of ETH they stake. This is far more energy-efficient. Validators are chosen randomly, weighted by the amount of ETH they have staked. Validators who act maliciously risk losing their staked ETH.

What happened to the miners?

After the Merge, Ethereum miners, who previously earned rewards for solving cryptographic puzzles, lost their primary revenue stream. Many miners transitioned to other cryptocurrencies that still utilize PoW, while some explored alternative revenue models. The transition was a significant shift in the Ethereum ecosystem.

What are the benefits of the Merge?

The primary benefit is the substantial reduction in energy consumption. PoS is significantly more energy-efficient than PoW. This makes Ethereum more environmentally friendly. Further, the move to PoS improves scalability by paving the way for future upgrades like sharding, which will further enhance transaction throughput and reduce fees. The Merge is also a crucial step towards Ethereum's long-term vision.

Common Questions and Answers:

Q: What is the impact of the Merge on ETH price? A: The Merge's impact on ETH price is complex and depends on various market factors. While some anticipated a price surge, the actual price movement was influenced by broader market trends and investor sentiment.

Q: Is the Merge completely finished? A: The main Merge event is complete, but the transition to a fully functional PoS Ethereum is ongoing. Further upgrades and improvements are planned.

Q: How secure is Proof-of-Stake? A: PoS is considered a secure mechanism, especially with a large and diverse set of validators. The risk of malicious behavior is mitigated by the economic incentives and the slashing mechanism that penalizes bad actors.

Q: How can I become an Ethereum validator? A: To become a validator, you need to stake a minimum of 32 ETH and run validation client software. There are risks involved, including the potential loss of your staked ETH if you act maliciously or your validator is offline for extended periods. Thorough research and understanding are crucial before staking.

Q: What is sharding and its relation to the Merge? A: Sharding is a scalability solution that will divide the Ethereum blockchain into smaller, more manageable parts called shards. This will significantly improve transaction throughput and reduce fees. The Merge was a necessary precursor to implementing sharding.