David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy | Lex Fridman Podcast #485
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.
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See below for timestamps, transcript, and to give feedback, submit questions, contact Lex, etc.
*Transcript:*
https://lexfridman.com/david-kirtley-transcript
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*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
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*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
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@lexfridman
November 20, 2025 at 10:53 pm
Thank you for listening ❤ Check out our sponsors: https://lexfridman.com/sponsors/ep485-sa
See below for timestamps, transcript, and to give feedback, submit questions, contact Lex, etc.
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
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-sa
Fin: AI agent for customer service.
Go to https://lexfridman.com/s/fin-ep485-sa
Miro: Online collaborative whiteboard platform.
Go to https://lexfridman.com/s/miro-ep485-sa
LMNT: Zero-sugar electrolyte drink mix.
Go to https://lexfridman.com/s/lmnt-ep485-sa
BetterHelp: Online therapy and counseling.
Go to https://lexfridman.com/s/betterhelp-ep485-sa
Shopify: Sell stuff online.
Go to https://lexfridman.com/s/shopify-ep485-sa
@nicholassmith7048
November 20, 2025 at 10:53 pm
1:22 pronunciation police here, I have to disagree with the United Statesian pronunciation of fission. If fission was pronounced like vision, it would be spelt like vision, with a single s, but alas, it is spelt with a double s and therefore you have to pronounce it the non-United Statesian way. I'm curious whether United Statesians mispronounce fissure as well 🤔.
@IntermountainGoldRefiners
November 20, 2025 at 10:53 pm
So basically we are calibrating the plasma and magnets for consistent fussion.
@MyApps-uf1dz
November 20, 2025 at 10:53 pm
and it's quite ridiculous that the guest praises the fission reactors as "safe", without addressing the most obvious problem: extremely toxic waste which will last for millions of years. Also even the folks at Chernobyl were confident that their plant was safe – and a statement like "the problem are the humans operating it and not the technology itself" is completely stupid
@ALL_VIDEO927
November 20, 2025 at 10:53 pm
not gonna lie I've been watching these tech interviews for months trying to connect everything and it finally clicked when I found 12 Last Steps by Selwyn Raithe… like the silicon shortages, autonomous weapons, all of it laid out step by step in these "cascades." kinda wild how this guy is basically describing what that book predicted but nobody's talking about it. idk if I'm overthinking but once you see the pattern you can't unsee it
@SALTANATEARAIN-BWP-PUNJAB
November 20, 2025 at 10:53 pm
not gonna lie I've been watching these tech interviews for months trying to connect everything and it finally clicked when I found 12 Last Steps by Selwyn Raithe… like the silicon shortages, autonomous weapons, all of it laid out step by step in these "cascades." kinda wild how this guy is basically describing what that book predicted but nobody's talking about it. idk if I'm overthinking but once you see the pattern you can't unsee it
@Moiz-Abbas19
November 20, 2025 at 10:53 pm
not gonna lie I've been watching these tech interviews for months trying to connect everything and it finally clicked when I found 12 Last Steps by Selwyn Raithe… like the silicon shortages, autonomous weapons, all of it laid out step by step in these "cascades." kinda wild how this guy is basically describing what that book predicted but nobody's talking about it. idk if I'm overthinking but once you see the pattern you can't unsee it
@RohitPrajapat-jt7sh
November 20, 2025 at 10:53 pm
not gonna lie I've been watching these tech interviews for months trying to connect everything and it finally clicked when I found 12 Last Steps by Selwyn Raithe… like the silicon shortages, autonomous weapons, all of it laid out step by step in these "cascades." kinda wild how this guy is basically describing what that book predicted but nobody's talking about it. idk if I'm overthinking but once you see the pattern you can't unsee it
@Kuldeepsinghania2468
November 20, 2025 at 10:53 pm
not gonna lie I've been watching these tech interviews for months trying to connect everything and it finally clicked when I found 12 Last Steps by Selwyn Raithe… like the silicon shortages, autonomous weapons, all of it laid out step by step in these "cascades." kinda wild how this guy is basically describing what that book predicted but nobody's talking about it. idk if I'm overthinking but once you see the pattern you can't unsee it
@MyApps-uf1dz
November 20, 2025 at 10:53 pm
Lex, you're missing the part where the Americans or the Russians are going to nuke humanity to save capitalism, therefore this "incredible future" probably ain't coming!
@kimjong-du3180
November 20, 2025 at 10:53 pm
We don't dig up plutonium from earth. There's supposedly only a few grams worth of plutonium in Earth's crust. Plutonium has to be made in a nuclear reactor. It's common knowledge if you paid any attention in chemistry or physics class.
@WilaminaCantrell
November 20, 2025 at 10:53 pm
Could entangled particals be used as outside switches to generate additional magnetic fields to strengthen plasma confinement?
@austindiaz7915
November 20, 2025 at 10:53 pm
I thought it was odd that David was surprised the watchdog group for nuclear safety endorsed nuclear fusion. He reffed to them as experts several times but by definition an expert would know fusion is much safer. His account of that event doesn't make sense to me, but other than that great interview. Salute Lex
@senorelroboto2
November 20, 2025 at 10:53 pm
27:30 that's just not true. If you go to the Sedan crater there's a nice big sign that says it was from a 104 kiloton explosion that was 70% fusion.
@rong1924
November 20, 2025 at 10:53 pm
What's crazy is that I work in Silicon Valley and every day I drive past a whole string of massive new data centers that were just built, and they are sitting there dark because the city failed to upgrade the power grid to accommodate them.
@jorgemalosti9308
November 20, 2025 at 10:53 pm
I'm a PhD student working on fusion research in tokamaks, and it's always a pleasure to discuss these topics. However, one aspect I rarely see addressed (especially by corporate voices) is the societal impact of abundant energy. Clean energy alone won't save us. Unless we move beyond the current capitalist mindset of relentless consumption, we'll continue to harm the planet. It's not just fossil fuels that are the problem, it's the economic model that demands infinite growth on a finite Earth
@wtfisthisbs1337
November 20, 2025 at 10:53 pm
these guys keep trying to create an energy source when God already gave us the sun, they have no melanin they have no shielding, yet they trying to sell energy instead of thinking of ways to use it for free
@brentonamar
November 20, 2025 at 10:53 pm
Thx to the editing team for the graphics on this one!
@MrExo_3D
November 20, 2025 at 10:53 pm
just because its unlimited clean energy doesn't mean it will be cheap. Profit runs the world
@vne5195
November 20, 2025 at 10:53 pm
Hopium is addictive.
@vne5195
November 20, 2025 at 10:53 pm
The Fukushima plant had extensive site engineering done when it was built. The Fukushima plant failed because it was operated as engineered. Had the operators upgraded and elevated systems, including the backup generators, in response to known risks, the plant could have withstood the earthquake and tsunami. TEPCO didn't do the upgrades because they were expensive. There failure modes for fission plant are so numerous that it's impossible to operate many plant, for many years without accidents resulting in loss of containment. In between massive radiation releases, the energy is clean, but when you have triple meltdown, the contamination is going to destroy any nearby real estate and leave countless without a home to live in. You need to acknowledge the obvious truth that nuclear power leads to mass contamination. Over & over…
@LTV_inc
November 20, 2025 at 10:53 pm
“If” this works, it would require a containment system that will be too expensive to build. It’s a 360* gamma ray gun that requires 5 feet of concrete. It’s a good idea but…
@daveepperson3469
November 20, 2025 at 10:53 pm
Clean fusion power in the next 3-5 years would be amazing! What a change it would make to the world!
However the world has been sold this promise for decades,with very little to show but more energy in than it puts out. What about reaching out to Daniel L. Jassby, Princeton Plasma Physics Lab who wrote the paper Voodoo Fusion Energy and have him on the show? Maybe we can get to the real truth on when this dream really can come true.
@ONEYEDPiRAT
November 20, 2025 at 10:53 pm
I believe Petroleum comes from the Earth itself not plants. It's the earths blood is the best way to say this, she'll keep producing it too. We're not going to run out. I can't prove any of this however I trust the source from which I received this information, Kryon lee carrol
@notsure8550
November 20, 2025 at 10:53 pm
Imperial Agents, Flavor is the only thing we got
@steves3422
November 20, 2025 at 10:53 pm
Fusion is always just 1 AU away. — Note: Things are learned through trial and error — so have at it.
@pavelshi
November 20, 2025 at 10:53 pm
Ты лучший!
@gordonicus4637
November 20, 2025 at 10:53 pm
Matrioshka brain Dyson sphere would still be detectable surely?
@gordonicus4637
November 20, 2025 at 10:53 pm
Fascinating discussion. Thank you!😃
@Wolf-ln5mk
November 20, 2025 at 10:53 pm
https://youtube.com/shorts/eqe7VYe10SA?si=7JhO9jt4F0kYfJwn❤
@kenbrohere
November 20, 2025 at 10:53 pm
How much energy is needed to heat hydrogen molecules to 100,000 degrees Celsius for only one minute?
@charliechen1
November 20, 2025 at 10:53 pm
I wanted to watch this to fall asleep to. Ended up watching two and a half hours…
@Laymante
November 20, 2025 at 10:53 pm
Inviting Bob Greenyer would be great!
@vykintasmorkvenas6839
November 20, 2025 at 10:53 pm
It's really interesting that in one case you'll get the sum smaller than that of constituents while in the other it's all way around. It seems like the Universe "likes" to release energy whatever it does 😂
@spikeccx
November 20, 2025 at 10:53 pm
Sorry but it's not the best answer and this guy is full ov shit
Helion is brilliant but still heat n stuff the others are still steam engineers
We need it but it will bring other problems!!
@GB-ws8zx
November 20, 2025 at 10:53 pm
"because…America" ROTFL.. right on!
@maitas44
November 20, 2025 at 10:53 pm
Amazing Podcast. Some questions that I got:
1- I didin't knew that 90% of an H bomob energy is from the fision part. I though it was lower. But thinking down this lines. Might it be possible to use a small fision reactor to ease the fusion reaction?
2- As he said that to get over 100 million degrees this requires an increase in speed of the particles, might it be that he is reaching a speed so big that the amount of energy to even increase the speed further gets hit by Einstein laws and gets close to infinite? I understand that thanks to its gravitiy the Sun can get away with way lower temperatures, but it might the case that to get fusion the way he wants to do it might get hit by Einstein's low.
3- I understand that the are using Maxwell's laws. I still can get my head around this Veritasium video https://www.youtube.com/watch?v=oI_X2cMHNe0 I wonder if they ask inside the company if all the electric engineers there understand this.
@88NiceGuyLondon88
November 20, 2025 at 10:53 pm
All this hustle and bustle but in the end the goal is to produce heat for making steam, to spin a turbine and generate electricity.. in other words a nuclear powered steam engine
-steam engine, machine using steam power to perform mechanical work through the agency of heat
In a steam engine, hot steam, usually supplied by a boiler, expands under pressure, and part of the heat energy is converted into work
@ozzmanislord5724
November 20, 2025 at 10:53 pm
Did he ever answer the question about cost?
Comments are closed.