Today, John Arnold—philanthropist and co-chair of Arnold Ventures—joins us to break down the real barriers facing next-gen nuclear energy. In a space filled with big promises and long timelines, John makes the case for why fusion and small modular reactors (SMRs) won't succeed without serious government intervention.

We talked about: 

• Why non-binding agreements in nuclear can be misleading
• The funding “valley of death” facing fusion startups
• How a milestone-based public-private model — modeled on NASA’s COTS program — could unlock progress

We also covered OpenAI’s updated release roadmap for o3 and GPT-5, the extended deadline for a TikTok sale, new agentic capabilities in Microsoft Copilot, and Midjourney’s first new image model in nearly a year.