In the world of blockchain technology, the consensus mechanism is an essential component for ensuring the integrity and security of a network. Without a consensus mechanism, there would be no way to ensure that all nodes on a network agree on the state of the blockchain.
Second layer blockchains, such as an Ethereum Virtual Machine (EVM) built on top of Bitcoin, play a crucial role in scaling and increasing the functionality of the underlying blockchain network. One of the most important aspects of these second layer blockchains is the consensus mechanism used to ensure their security and integrity. In this post, we will explore why a second layer EVM on Bitcoin needs a consensus mechanism and how it differs from other second layer solutions like rollups and the Lightning Network.
First, it's important to understand the concept of rollups. Rollups are a second layer scaling solution that uses smart contracts to bundle multiple transactions off-chain, while still maintaining the security of the underlying blockchain. Arbitrum and Optimism are examples of rollups that use optimistic rollups. However, these rollups are not decentralized since a central party controls the zk-SNARK or optimistic smart contract on the base layer. Or in different words, there is a single party that controls admin keys to the contract and runs the code. The best question to ask to figure out if something is decentralized: Who has the keys and who can change the code? This centralization creates a risk of censorship and fraud.
On the other hand, the Lightning Network is a second layer solution for Bitcoin that does not require a consensus mechanism. It works by creating a network of payment channels between nodes that can transact off-chain, with the state of the network constantly being mapped back to the Bitcoin parent chain. However, this solution is not applicable to an account-based blockchain like Ethereum, which cannot map to the UTXO model used by Bitcoin.
In conclusion, building an account-based second layer blockchain like Ethereum on top of Bitcoin requires a consensus mechanism to ensure its security and integrity. Solutions like rollups and the Lightning Network do not provide this level of decentralization and functionality respectively. Therefore, a consensus mechanism is necessary to ensure the security and integrity of the network. Without a consensus mechanism, a second layer EVM on Bitcoin would be vulnerable to fraud and could not function as intended.