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Lex Fridman PodcastDr. David Kirtley on Lex Fridman: Why the H-bomb is fission
Why 90 percent of hydrogen bomb energy still comes from fission, not fusion; Helion uses pulsed magnetoinertial and deuterium from seawater.
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Episode Details
EPISODE INFO
- Released
- November 17, 2025
- Duration
- 2h 36m
- Channel
- Lex Fridman Podcast
- Watch on YouTube
- ▶ Open ↗
EPISODE DESCRIPTION
David Kirtley is a nuclear fusion engineer and CEO of Helion Energy, a company working on building the world's first commercial fusion power plant by 2028. Thank you for listening ❤ Check out our sponsors: https://lexfridman.com/sponsors/ep485-sb See below for timestamps, transcript, and to give feedback, submit questions, contact Lex, etc. *Transcript:* https://lexfridman.com/david-kirtley-transcript *CONTACT LEX:* *Feedback* - give feedback to Lex: https://lexfridman.com/survey *AMA* - submit questions, videos or call-in: https://lexfridman.com/ama *Hiring* - join our team: https://lexfridman.com/hiring *Other* - other ways to get in touch: https://lexfridman.com/contact *EPISODE LINKS:* David's X: https://x.com/dekirtley David's LinkedIn: https://bit.ly/4qX0KXp Helion: https://www.helionenergy.com/ Helion's YouTube: https://youtube.com/HelionEnergy *SPONSORS:* To support this podcast, check out our sponsors & get discounts: *UPLIFT Desk:* Standing desks and office ergonomics. Go to https://lexfridman.com/s/uplift_desk-ep485-sb *Fin:* AI agent for customer service. Go to https://lexfridman.com/s/fin-ep485-sb *Miro:* Online collaborative whiteboard platform. Go to https://lexfridman.com/s/miro-ep485-sb *LMNT:* Zero-sugar electrolyte drink mix. Go to https://lexfridman.com/s/lmnt-ep485-sb *BetterHelp:* Online therapy and counseling. Go to https://lexfridman.com/s/betterhelp-ep485-sb *Shopify:* Sell stuff online. Go to https://lexfridman.com/s/shopify-ep485-sb *OUTLINE:* 0:00 - Introduction 3:14 - Nuclear fission vs fusion 13:14 - Physics of E=mc^2 18:28 - Is nuclear fusion safe? 23:50 - Chernobyl 30:17 - Geopolitics 32:12 - Extreme scenarios 39:07 - How nuclear fusion works 1:11:59 - Extreme temperatures 1:17:00 - Fusion control and simulation 1:28:54 - Electricity from fusion 2:02:59 - First fusion power plant in 2028 2:09:52 - Energy needs of GPU clusters 2:20:16 - Kardashev scale 2:28:12 - Fermi Paradox *PODCAST LINKS:*
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SPEAKERS
Lex Fridman
hostDavid Kirtley
guestNarrator
other
EPISODE SUMMARY
In this episode of Lex Fridman Podcast, featuring Lex Fridman and David Kirtley, Dr. David Kirtley on Lex Fridman: Why the H-bomb is fission explores Helion’s David Kirtley explains pulsed fusion and rewiring Earth’s energy future Lex Fridman interviews nuclear engineer and Helion Energy CEO David Kirtley about nuclear fusion, its physics, and Helion’s unconventional pulsed magneto‑inertial approach. They contrast fusion with fission, explain why fusion is inherently safer and non‑proliferating, and delve deeply into plasma physics concepts like E=mc², confinement, beta, and field‑reversed configurations (FRCs).
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