Proof-of-Entropy-Minima (PoEM)
Introduction to PoEM
Quai Network’s Proof-of-Entropy-Minima consensus mechanism.
Proof-of-Entropy-Minima is based heavily off of Proof-of-Work Nakamoto Consensus. A strong understanding of Proof-of-Work consensus is
highly recommended before reading the PoEM documentation. A detailed explanation of Nakamoto Consensus can be found
here.The original PoEM concept was introduced in a 2023 research paper.
A more recent paper with a formal security proof
“A Better Proof-of-Work Fork Choice Rule”.
The Consensus Problem
Traditional blockchains face a fundamental challenge: when two valid blocks are found simultaneously, the network temporarily splits. This creates:- Uncertainty: Transactions may be reversed if you’re on the losing fork
- Wasted energy: Miners work on competing chains that will be discarded
- Limited scalability: Only one chain can win, limiting overall throughput
How PoEM Works
PoEM is inspired by Bitcoin’s Proof-of-Work (PoW) Nakamoto Consensus, but with a crucial improvement. Like PoW, PoEM uses hashes generated by competing miners to verify proposed blocks. However, PoEM differs in how these hashes are compared and measured. Think of entropy like a “uniqueness score” - PoEM always picks the block with the highest uniqueness score, ensuring every node makes the same choice. Unlike PoW, which treats all blocks that meet a certain difficulty level as equally valid, PoEM measures the intrinsic block weight to calculate the entropy, or randomness, removed by each proposed block. This ensures that all nodes will always prefer one particular block over any other options. Under PoEM, all nodes immediately agree on the next block as soon as they become aware of it, eliminating any disagreements caused by delays in the network. Two nodes running PoEM will always agree on which block is next in the chain.PoEM vs Traditional Consensus
| Traditional PoW | PoEM |
|---|---|
| ”Good enough” blocks compete | Best block always wins |
| Network splits temporarily | Network stays unified |
| Resolution takes time | Resolution is instant |
| Wasted mining effort | All mining contributes |
| Limited to single chain | Enables infinite shards |
Key Benefits
By removing contention from consensus, PoEM enables “perpetual consensus” - the network never needs time to resolve conflicts because conflicts never occur. This breakthrough provides several advantages: For Users:- Instant finality: Transactions are immediately final, no waiting for confirmations
- Predictable fees: No congestion from competing chains
- Unlimited capacity: Network can scale infinitely without degrading security
- Energy efficiency: No wasted mining on discarded forks
- True decentralization: Can coordinate unlimited execution shards
- Enhanced security: All mining power secures the entire network
Instantaneous Fork Resolution
Given the same set of information, every node in the system will always make the same decision on the next block in the sequence.
Faster Finality
Proof-of-Entropy-Minima offers a faster mathematical guarantee of on-chain inclusion than all existing consensus mechanisms.
Coordinating Infinite Execution Shards
Perpetual consensus is a prerequisite to coordinating an infinite number of execution shards. Mechanisms that take any time to resolve
contention in consensus are ineffective at coordinating more than one chain.