From Whiteboard to Mainnet Podcast | Episode 3: Proposer-Builder Separation

Why It Matters

These dynamics reshape who captures on-chain value and influence block inclusion, with implications for decentralization, censorship resistance, and the economic incentives of validators and users; policy and protocol choices around PBS and private order flow will determine whether Ethereum remains broadly permissionless or drifts toward concentrated infrastructure.

Summary

Guests from academia and the Ethereum Foundation explained why specialized block builders emerged: extracting complex MEV (maximal extractable value) opportunities requires sophisticated tooling and continuous market activity that ordinary validators are ill-equipped to perform, so builders and middleware like MEV-Boost now connect many validators to shared builder markets. Private order flow — transactions routed outside the public mempool — has grown to dominate block value (research cited ~67% of value while representing ~20% of gas) and builders now produce the vast majority of blocks. The conversation reviewed recent academic work on the economics of payment-for-order-flow and PBS (proposer-builder separation) and debated how current architectures concentrate power among a small set of builders and relays. Panelists also summarized community responses and design tradeoffs aimed at preserving fair validator rewards while mitigating centralization risks.

Original Description

From Whiteboard to Mainnet is a new podcast series co-hosted by Columbia University’s Center for Digital Finance and Technologies (CDFT) and the Ethereum Foundation’s Academic Secretariat. This episode is also co-hosted by the newly formed Columbia–Ethereum Center for Blockchain Protocol Design.

The series brings together academics and Ethereum ecosystem contributors for focused, candid conversations. Each episode explores a specific topic or open problem, pairing leading researchers from academia with contributors from the Ethereum Foundation to share and compare perspectives.

The second episode will be co-hosted by Fahad Saleh (Columbia University/University of Florida), and Shyam Sridhar (Ethereum Foundation), and will feature Agostino Capponi (Columbia University), Ruizhe Jia (Stanford University), Thomas Thiery (Ethereum Foundation), and Julian Ma (Ethereum Foundation) in a discussion around Proposer Builder Seperation, Payment for Order Flow, and Centralization risks in Ethereum. The session will begin with a discussion of the key insights from Agostino and Ruizhe’s work, followed by a broader conversation on how the Ethereum community has responded. It will conclude with a look at frontier topics such as BuilderNet and enshrined PBS (ePBS).