This article is compiled and organized by BlockWeeks
EthereumBeacon Chain (Beacon Chain) has completed its first-ever hard fork, codenamed Altair. This upgrade brings stricter penalty mechanisms, a fairer way of tracking behavior, and assigns new responsibilities to network participants—that is, validators.
The Beacon Chain is the brand-new consensus chain activated after the Ethereum 2.0 upgrade. As the name suggests, it is like the "eternal flame" of the new network, providing the consensus foundation for the entire PoS system. Altair is a backward-incompatible, system-wide upgrade that was officially activated on October 27, 2021.
Timeline: Altair Is Just a "Warm-Up"
Altair is named after the twelfth-brightest star in the night sky. In the eyes of protocol developers, it is more like a "warm-up match" in a series of upgrades—the real main event is the much more complex and risky "Merge" (The Merge) that follows.
The roadmap is roughly as follows: first, the Beacon Chain completes its first hard fork, Altair; then in December 2021, the Ethereum PoW main chain will undergo the "Arrow Glacier" upgrade to prepare for the eventual convergence of the two parallel chains; according to protocol developers' estimates at the time, the Merge would be ready for deployment by the end of March 2022.
Once the Merge is completed, Ethereum will permanently end mining, replacing proof-of-work (PoW) with the Beacon Chain's proof-of-stake (PoS) mechanism.
It is particularly important to note that, unlike node operators on the PoW chain, individuals and institutions running Beacon Chain software need to upgrade for all three hard forks, including the one in December. The reason is that connecting to the Beacon Chain itself requires users to run both an Ethereum PoW node and a Beacon Chain node.
Moving to PoS: Energy Consumption Drops by More Than 99%
One major reason Ethereum developers value PoS is that it will make mining operations a thing of the past, thereby reducing the network's energy consumption by more than 99%. Since the network no longer needs to consume large amounts of electricity and computing power, post-Merge Ethereum is expected to further distinguish itself from Bitcoin and become a relatively more environmentally friendly crypto asset.
Since Ethereum launched, protocol developers have been planning a full transition to PoS. But the explosive growth of user activity significantly slowed progress: the entities participating in the protocol's decentralized governance expanded from a handful of people at the beginning into a massive collective. Faced with a vast DApp ecosystem and diverse participants—users, developers, miners, exchanges, wallet service providers—collective decision-making about Ethereum's future has become increasingly difficult.
However, in sharp contrast to the Bitcoin community, the Ethereum community has not fallen into the political tug-of-war of decentralized governance that leaves the protocol stagnant for long periods. Instead, it continues to move forward and remain innovative at the forefront of blockchain technology.
Decentralization: Letting Light Clients Run on Phones and Laptops
In addition to moving Ethereum one step closer to a "greener" PoS, Altair's most important significance lies in laying the foundation for a "lightweight" version of the Beacon Chain code—light clients of this kind can run on almost any device, from smartphones to laptops.
With mobile-friendly client software, small ETH holders who previously could only earn returns through centralized channels such as exchanges or staking service providers can more easily connect to the network using their own hardware, thereby regaining control of their assets. The more staking value is dispersed among many participants rather than concentrated in the hands of a few large players, the higher the security and reliability of the entire protocol.
At present, Ethereum's network decentralization is superior to layer-1 challengers such as Solana, Polkadot, and Near, but the transition to PoS may also allow network control to fall more into the hands of "capital (supply)," bringing centralization concerns. To hedge against this risk, Ethereum developers are introducing corresponding protocols so that small holders can also participate in PoS consensus.
Whether originating from Altair or from the broader Merge process, those changes that make Ethereum more decentralized and easier for ordinary users to participate in will ultimately increase the global adoption of this cryptocurrency and strengthen outside trust in Ethereum's DApp ecosystem.
Altair's Three Core Changes
Altair's core features can be grouped into three categories: penalty parameter updates, reform of the inactivity score, and the sync committee mechanism.
1. Penalties Increased Across the Board
As a result of Altair taking effect, penalties on the Beacon Chain for inactivity and malicious behavior will be significantly heavier:
- When block finality stalls, the time required for offline validators to be penalized by the network will be shortened by about 13%;
- The minimum slashing amount will increase from 0.25 ETH to 0.5 ETH;
- The "correlated" penalty for malicious behavior—that is, the additional penalty that scales proportionally with the total number of validators slashed at the same time—will increase from a multiplier of 1x to 2x.
The logic behind increasing penalties is to restore the cost of attacking or manipulating the network to the Beacon Chain's original design intent. Since the protocol launched on December 1, 2020, the parameters written into the code had been deliberately relaxed in order to encourage users to stake ETH during the Beacon Chain's most nascent and experimental deployment phase. After nearly a year without major problems, protocol developers began to "tighten the reins" through Altair.
2. Sync Committees and Reward Structure
Under the original mechanism, validators not selected to produce blocks are assigned to attestation committees. Each committee consists of at least 128 validators, and each member needs to vote on a proposed block to confirm that the data in the block is valid—this is block attestation.
After Altair, validators will also be assigned to participate in "sync committees," responsible for providing useful data for information relayed to light clients, such as the latest epoch information.
After the upgrade, about 3% of validator rewards will come from sync committee-related duties; but nearly 85% of rewards will still come from block attestation—whose role is to confirm the progression of a single blockchain and determine which chain is the canonical chain in the event of a chain split.
3. Light Client Infrastructure
One of Altair's goals is to build the building blocks for light client support, so that DApps, wallets, and other blockchain services can use them to create mobile-friendly product forms. This will improve network decentralization over the long term and drive adoption of the Ethereum protocol.
Who Must Upgrade?
Altair is the first major change to the code specification for a network that has accumulated nearly $30 billion in staked ETH: it imposes heavier penalties on violating validators, resets parameters to make validator rewards fairer, and lays the foundation for light client support.
All validator node operators must upgrade to the latest software in order to continue receiving rewards. Miners and other service providers who only run nodes on Ethereum's parallel PoW chain do not need to participate in this upgrade.
However, whether on the Beacon Chain or the PoW chain, all node operators need to upgrade their machines in December 2021 for a minor code change affecting the mining difficulty curve. The December Arrow Glacier upgrade and the Altair upgrade are the last two adjustments to the Ethereum protocol before the Merge, after which all attention will turn to the Merge.
Conclusion: A "Barometer" for the Merge
As the first checkpoint before the Merge, Altair is expected to serve as a yardstick for measuring whether the Beacon Chain can smoothly activate protocol changes, as well as its flexibility and readiness. At the same time, by laying the foundation for light client software, Altair is also expected to help resist centralizing forces after Ethereum switches to PoS.
