Vitalik Buterin: The Advantages of Ethereum PoS You Might Not Know

Author of this article: Vitalik Buterin, translated by ETH Chinese Station.

We often talk about how the resources consumed by PoS consensus are much less than those of PoW, and we also discuss some key benefits brought by PoS, such as economic finality, but we should not forget some secondary benefits after transitioning to PoS. Theoretically, most of these benefits can be realized immediately after the merge.

Block Time Distribution: In the PoW consensus mechanism, block distribution is based on a Poisson distribution, so there is a significant variation in block times, with an average block time of 13 seconds, but sometimes it can exceed 30 seconds or even 60 seconds. After you send a transaction, you typically have to wait an average of 13 seconds for the next block to appear. The PoS mechanism has a fixed block time, generating a block every 12 seconds, with an average waiting time of 6 seconds after sending a transaction. The only exception is when the proposer is offline, which is a rare occurrence. After the implementation of EIP-1559 on the mainnet, this will greatly improve the user experience on Ethereum.

Faster Block Confirmation Before Finality: In terms of finality for PoS, a block is confirmed and cannot be rolled back after about two epochs. However, before that, the speed of security enhancement is much faster than in PoW, because under the LMD GHOST fork choice rule, hundreds of attestations can be produced simultaneously, resulting in a faster convergence speed compared to the PoW model (where each block confirmation requires consensus across the entire network). After 12 seconds, a block can be verified by hundreds of validators, making rollbacks very difficult.

Better Light Client Protocols: PoW Ethereum has light clients, but their efficiency is far below what they could achieve, and starting and maintaining them still requires a considerable amount of time and resources. Learning from the experiences of PoW, the design of PoS light client protocols is more refined, requiring only a few kilobytes of data to be downloaded daily to stay in sync. This makes the built-in light clients in browsers and mobile PoS light client wallets more feasible, reducing reliance on centralized service providers.

Faster Detection of Network Issues: In a PoW network, if half of the nodes go offline or cannot operate normally due to vulnerabilities and hacker attacks, it takes some time for other nodes in the network to detect this, as initially there is not enough information to distinguish what is happening from random events. In contrast, in a PoS network, if the participation of nodes in a single slot drops from 99% to a lower level, it is very easy to notice, and you will immediately know that there is a problem with the network.

There are many more subtle benefits. The time given to transition from the PoW chain, which the Ethereum network protocol stops supporting before the merge, to the PoS chain provides us with a natural coordination opportunity to reset the amount of data that clients need to download. The existing data structures in the beacon chain (especially the lists of historical block roots and state roots) make it easier to access historical records within the EVM (which is the same benefit that EIP-2935 aims to achieve). The SSZ structure makes it easier to implement any type of historical proof; furthermore, for the entire protocol, a more complete transition from RLP to SSZ could greatly simplify the Merkle proof generation process.

The merge involves not just the transition to PoS, but also brings a series of benefits!