Navin Chaddha runs Mayfield, one of the oldest firms in Silicon Valley, and has backed founders through several platform shifts. His current thesis is that the second infrastructure wave under AI looks like deep tech, advanced engineering, and energy systems: power, cooling, optics, memory, switching. Recent checks include Lumilens, Upscale AI, AI Fabrik, and Hang Ten, three of them to founders he has backed before. He is on record that nobody can see five years out in AI, and he still sizes markets over five to seven year windows. The closing conversation is about what has to be true about a business model before physical AI is investable at Mayfield's scale.