1/ Solana is rolling out the most significant change to its core protocol since launch: a new consensus mechanism called Alpenglow. This thread breaks down how Alpenglow works, how it compares to Ethereum's Proof-of-Stake, and what this means for developers, users, and investors. 🧵

2/ Alpenglow replaces Solana’s original Proof of History + Tower BFT consensus with two new components: – Rotor, for fast block propagation – Votor, for fast and simple voting The goal is to improve throughput, simplify the protocol, and reduce time to finality by over 100×

3/ Under Alpenglow, Solana achieves finality in ~150 milliseconds. This is deterministic finality. Once a transaction is confirmed, it is permanent. Not probabilistic, not “optimistic.” It replaces Solana’s previous ~12.8s finality under Tower BFT and removes PoH entirely.

4/ Rotor uses erasure-coded shreds and one-hop relays to disseminate blocks efficiently. Rather than relying on leader upload bandwidth or gossip trees, Rotor saturates total network bandwidth using stake-weighted relays. Result: faster propagation, lower latency.

5/ Votor replaces Tower’s vote locking and multi-round finality with a dual-mode process: – If ≥80% of stake votes, block is finalized in one round – If ≥60% votes, two rounds are run concurrently Finality = min(δ₈₀%, 2×δ₆₀%), where δ = network delay among those % of stake.

6/ Transaction finality = when a transaction becomes irreversible It matters because until then, it can be censored, reordered, or dropped in a fork Finality is key to censorship resistance and off-chain trust Solana now finalizes in ~0.15s Ethereum takes ~12.8 minutes (2 epochs)

7/ Block production time: – Solana (Alpenglow): 400ms fixed slots – Ethereum: 12s slots Throughput: – Solana: 1,000+ TPS in practice – Ethereum: ~30 TPS on L1 (relies on L2s for scale) Finality: – Solana: ~0.15s – Ethereum: ~12.8m

8/ Ethereum prioritizes decentralization and safety. It tolerates 33% adversarial stake and has ~1M validators. Finality halts with >⅓ offline. Solana tolerates 20% malicious + 20% offline stake. ~2K validators. centralized, but optimized for speed and fault tolerance under real-world conditions

9/ Ethereum’s design now treats L1 increasingly as a data availability and finality layer. (Further evident with RISC-V proposal) Execution is expected to happen on rollups (L2s), which inherit Ethereum’s security but offer faster, cheaper txs. Solana handles execution and consensus directly on L1.

10/ This divergence is strategic: Ethereum leans into a modular architecture: – L1: Finality + DA – L2s: Execution + UX Solana remains monolithic: consensus, execution, and settlement occur on the same layer. Only now with millisecond latency.

11/ On developer UX: – Solana finality allows real-time confirmation of transactions – No confirmation polling or block depth logic – Vote txs removed. Cleaner app code – Execution + finality = one step Ethereum devs must account for reorg risk, L1→L2 bridging, and eventual confirmation

12/ On user experience: – Solana UX is fast and cheap (sub-second txs, <$0.001) – Ethereum L1 is secure but slow and expensive – L2s improve Ethereum UX, but add cognitive and technical overhead (bridges, network switching) Solana delivers the experience directly on L1.

13/ With Alpenglow consensus complexity is also reduced: – PoH eliminated – Voting off-chain via BLS certs – No vote spam – Leader failures skipped automatically This improves validator efficiency and lowers hardware cost ceilings, though performance requirements remain high.

14/ Security tradeoffs: – Solana: <20% adversarial stake tolerated – Ethereum: <33% Solana trades worst-case Byzantine safety for best-case performance and faster recovery. Ethereum prioritizes predictability and robustness under attack.

15/ Implications for applications: Solana now enables real-time on-chain apps: – Order book DEXs – High-frequency trading – On-chain games – Social protocols – Payments & remittances – Real-time DeFi automation No need for L2s to achieve usable latency.

16/ Bottom line: Ethereum is a secure, decentralized base layer for a modular rollup stack. Solana is a high-performance monolithic chain optimized for real-time use. Alpenglow doesn’t try to replicate Ethereum, it offers fundamentally different blockspace. Choose accordingly.