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David Kirtley: belief

17 Nov 2025 Lex Fridman Podcast #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy

“I think as I have gone further and further in building fusion systems that work, I’ve become more optimistic around the Fermi paradox specifically.”

— David Kirtley

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Everything needed to verify it.

Speaker
David Kirtley
Attribution
Verified speaker
Claim type
belief
Recorded
17 Nov 2025
Publisher
Lex Fridman Podcast

Transcript context

…And we’re good at surviving. Life as we know it on Earth seems to find a way, and intelligent life as we know it, human life, seems to find a way. We do a lot of painful things along the way, but in the end, we somehow survive. It’s interesting. There’s something in the human spirit… …That allows us to survive. So I have a lot of optimism that the super powerful technologies that we create will eventually lead to us still surviving for thousands of years. But then, why are the aliens not here, though? So maybe it’s also possible that it’s really difficult to traverse space. Maybe it really is that difficult. The physics makes it not easy. There’s a lot of space, and it’s just hard to travel. I think as I have gone further and further in building fusion systems that work, I’ve become more optimistic around the Fermi paradox specifically. And there are several of them. I think you’re referring to something called the great filter. Something happens that filters out life. The dark forest is another philosophy around, “Sure, it’s out there, but everybody’s hiding ’cause they don’t want to be noticed.” But I think about something else, actually. The philosophy that I’ve always loved, and I’m going to pronounce this wrong, so I apologize, Matrioshka brains… …is that, and that’s Kardashev level two, that civilizations get so advanced, and they focus not on expanding physically and expanding in space and expanding their reach by planting flags in new places, but grow their cognition, grow their ability to think. They grow their brain. They grow their intellect. And I feel like in the last few years, we’ve seen a massive trend that maybe this is the thing that happens, and that we do grow our intellect, and we grow the intellect of the species by AI and advanced tools. And as a society, we can just get smart enough that we don’t need to go plant those flags everywhere. And so the Matryoshka brain is a Dyson sphere where a civilization has covered the entire sun in essentially solar panels or collects its light in some way and uses all of that power to power intelligence, to power computers, and to power brains. And I think we’re a ways away from that, but maybe AI and fusion together gets you actually along that path sooner. And I’m excited by that outcome of the Fermi paradox. And then at that point, those civilizations have a star that you can’t find anymore ’cause it’s all covered and are there thinking and growing their intellects rather than actually having to physically expand. Yeah. Exploring and expanding in the realm of cognition and consciousness versus in the realm of space and time as we 21st-century colonizer humans think like. Maybe 22nd-century humans will be thinking fundamentally differently. Yeah, that’s a beautiful, beautiful vision of the future. Speaking of beauty, you’ve been doing a lot of really interesting things in a lot of interesting disciplines. What to you is… ridiculous question, is the most beautiful idea in physics and nuclear engineering, in nuclear fusion and power plants? What ideas do you just step back and are in awe of?…

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