YouSaid · the spoken record

David Kirtley

lines on the record: 180
first: 2025-11-17
most recent: 2025-11-17
sittings or episodes: 1
sources: podcast

Every line below is reproduced as it was said and linked to the record it came from. Nothing here is summarised or generated. Directory · Search · Corrections

“Fusion power plants can't be used to make nuclear weapons fundamentally that the processes in fusion aren't the same processes that happen in nuclear bombs and nuclear weapons. And so it's actually one reason I started infusion and most of our team thinks about the mission of fusion of delivering clean, safe electricity is it also can't be used to make weapons. And I think that's a little bit of a distinction from traditional nuclear fission reactors is that while I totally believe as a nuclear engineer we build power plants now that are safe, that aren't going to have reactions, they use a fuel, uranium and plutonium that can be used to be made to make nuclear weapons. That we know that if you take enough fissile material together, enough uranium and plutonium, put it in a small volume that”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“Past was where some of the problems actually happened. And so I look to that less as a A failure of the engineering, of the power plants, and more of the humans around those systems that we should be operating these plants as designed, and then I believe they're safe. And that gets to some of the atomic weapons questions that I think are the other part around nuclear reactors and fission reactors that are concerning for me.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“So, with Chernobyl and Fukushima, I actually put Three Mile Island in a different category. In fact, some of the recent news in the last year is that we're going to be restarting Three Mile Island because there's such a need for clean baseload power. So that's actually a very interesting other topic we should talk about is why and how we're doing that. But more than that, going back to the accidents that did happen, in both of those systems, you can point to the human failure rather than the engineering failures of those systems that in Fukushima specifically there were multiple nuclear fission reactors on the same site that successfully kept running through the tsunami, totally successfully, and were only later shut down for more political reasons. But the old one, the oldest of them that had been on site for a long period, and maybe too long, I think some experts have looked at this.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“The engineering actually. I believe the engineers have solved these problems. The problem comes from humans, and the problem comes from other things around nuclear power. You have to enrich that uranium to put it in a plant. And the plant's safe, but you had to enrich that uranium. And that is some of the problem. Or a plant is designed to run for a certain number of decades safely. But do we run it longer than that? And so those are where I think the real challenges happen is more with the humans around these systems than the engineering of the power plants themselves.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, we've been talking about the reaction processes themselves. But I think fundamentally let's take a step back and look a little broader and say, let's look at what we care about, which is the power plant, making electricity. And I look at this from a nuclear engineer's point of view. I spent a lot of years studying these systems. And modern vision reactors, I believe, are engineered to be safe. They're engineered in ways where as those reactions may be speed up and those systems get hotter, they actually are built to expand and cool down passively and natively. And there's protection systems in place that modern systems are quite safe from an engineering perspective. And so I believe that we have figured out how to build nuclear fission reactors in a way where the engineering of the power plant is safe. I would say that I look back at the history of what we've built over time and the challenge hasn't come to”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“And then the key is at the same time, you want to make sure that the whole thing is in water is typically the cooling fluid. There's some more advanced fission reactors that have different cooling fluids. But water typically, where then that absorbs both the heat and those extra neutrons. And so you use the water and the fluid to then run a steam turbine to do traditional electricity generation and output electricity through your steam turbine. You end up with complicated systems of flowing liquids and flowing water, balancing the heat. A lot of fission reactor design comes from that thermal balance of keeping this reaction going, making sure it doesn't speed up, because that's an uncontrolled chain reaction, which you would not want, and balancing the cooling and the output of getting the water out of it.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“People design fission reactors such that you have just the right balance of enough neutrons are made such that the reaction is continuing, but not so many neutrons are made that it speeds up because you don't want it to speed up.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“In a nuclear fission reactor, you put enough of this fissile material, your uranium plutonium together such that as these unstable molecules, these unstable atoms crack open and break apart, they release heat that the component parts of those are actually quite hot. And so not only are the component parts that the uranium breaks into, and it's a whole spectrum of different atoms and atomic nuclei are hot, but it also releases neutrons. It also releases more of these uncharged particles. And if you do it right, this fissile material will be next to other fissile material. And so that neutron will then go and bombard another uranium nucleus, again, opening that up and releasing more heat and more of these neutrons. And that's how you have those reactions of a self-supporting chain reaction. And that chain reaction then continues.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“Fundamentally, as a source of energy, in fusion, you're taking these lightweight isotopes, you're bringing them together, you're releasing energy, and that energy is in the form of charged particles. It's already in the form of electricity. Fusion itself has electricity built into it without a lot of the steam or thermal system requirements. And so that's a really nice fundamental benefit of fusion itself. Also, this reaction that's really hard to do turns itself off. So you end up with that fusion is fundamentally safe. And that's really a key requirement of any industrial system is that it turns itself off and is safe. You turn the key off on your car. You know it's going to turn off.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“Obviously, fusion is not that. We've talked about why, but also the self sustaining part and that a reactor is self-sustaining. You take your hands off of it and it keeps going. In fusion, that doesn't happen. And we know because we have to do it every day and it's really hard to do. And so we actually use the word generator because we don't talk about, for instance, a natural gas reactor is that if you stop putting in fuel, it turns off. And the same thing happens in fusion. And so we're pretty careful about making sure we talk about that as a generator where you're putting in fuel, you're getting electricity out, and then when you stop putting in fuel, it just shuts off. And you can go even one step further and say, what am I going to do with this fusion that powers the universe? And what does humanity want out of this? And what we want is electricity. We don't simply want a set of reactions or even heat and energy. That's great. But what I really want is electricity.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“But we have other forces we get to use. We can use the electromagnetic force, which the sun doesn't get to do to apply those forces. And I actually want to take a pause right there and point out a word. Historically, we've used the word reactor around fusion, but I don't think that's right. And for me, we're really careful about this terminology when we look to how that word is defined. And we can look to how the experts define it. It doesn't really apply to fusion. So the nuclear regulatory commission, the NRC, defines reactor as, I have it right here, a nuclear reactor is an apparatus other than atomic weapon designed or used to sustain nuclear fission in a self-supporting chain reaction. And there's two big parts to that. That one, fission reaction.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, and I think fundamentally it's that in a lot of ways fusion is hard and fusion is easy. Nuclear fission happens at room temperature that this uranium and plutonium is so likely to break apart already that simply the adding of one of these neutrons, one extra particle, will then break it apart and release energy. And if you have a lot of them together, it will create a chain reaction. Fusion, that doesn't happen at all. Fusion is actually really hard to do. You have to overcome those electromagnetic forces to have a single fusion reaction happen. And so it takes things like in our sun, we have what is called gravitational confinement, where the gravity, literally the mass of the fuel itself is pulling to the center of the sun and it's pulling. So there's a large force that's pulling all that fuel together and holding it and confining it together such that”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“And then once you get within a very close distance, on the order of the scale of those nuclei themselves, of those atomic nuclei. So the tiniest thing you could imagine and probably way smaller than that, these particles then are And that mass equals mc squared is energy.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“So, in fusion, you take these lightweight isotopes like hydrogen and deuterium. And as you combine them and take these molecules and get them closer and closer together, some really interesting fundamental physics happens. So first these atomic nuclei are charged. They have an electric charge. And they like charges repel. And I think everybody is familiar with that, where you take two positive charges and you try to push them together and the electromagnetic force between them repels them. So you have a force that's actually pushing against them. So infusion, you work to get your fuel very hot, very, very high temperatures, 100 million degree temperature. Temperature really is kinetic energy. It's motion, it's velocity, so that these particles are moving so fast that even though they're coming together and there's this repulsive electromagnetic force, they can still come close enough that another force comes into play, which is the strong force.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“That's correct to say at today's power level. I think what's interesting is the idea that as we deploy the same power source that power is the universe here on Earth as humans, can we do more? Can we have access to much more electricity and much more energy and do really interesting things with that? And still there's large amounts, millions and millions of years of power, even at much higher output power levels for humanity.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“We use an isotope of helium. The nucleus is called the helion, which is what we base the company after, which is two protons and one neutron. It's a light helium molecule.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“And mostly that's just in water. Mostly that it's a mix of, we call this actually heavy water where you have normal water that you're used to. We talk about and you learn in school is H2O, where there's two hydrogens and oxygen in a nucleus in the molecule. And deuterium or heavy water is D2O to deuteriums and an oxygen. In reality, it's actually an interesting mix where you have some HDO, some mix of hydrogen and deuterium. You also have other hydrogen in a species. Tritium is another one, or you add a second neutron to that hydrogen, and then you can have T2O tritiated water. And that's something that comes up and we need to talk about it. at some point. And there's other, as you go up the periodic table, you get add two protons and you get helium. And so helium, the most common helium, is helium-4, which is two protons and two neutrons.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“Everywhere, and we particularly use a type of hydrogen called deuterium, which is a heavier isotope of hydrogen. Hydrogen is typically one proton and one electron atomic mass of one. Deuterium is an atomic mass of two, which is a proton, which is charged particle, and it has a neutron in its nucleus, which is an uncharged particle. And so that's deuterium as the fuel. Now, deuterium is also found in all water on Earth, in the water I'm drinking right now. It's in my body. It's in Coca-Cola. It's everywhere. And safe and clean, and one of those fundamental particles that was born in the cosmos. And we estimate that in seawater here on Earth, we have, if we powered at our current use of electricity. All of humanity on fusion, somewhere between 100 million years and a billion years of fuel in hydrogen and deuterium here on Earth.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“So for fission, uranium, and plutonium, we don't make those nuclei. Those right now for humanity, those have been made in the primordial universe through supernova and Big Bang and the initial formation of the universe where matter was created. And so we dig those up. We dig up uranium, plutonium out of the ground. And in fact, most plutonium we make from uranium. And we can talk about how to enrich uranium if we want to go down that road. But that's how we get those molecules and nuclei. For fusion materials, hydrogenetic species or hydrogens are primordial in the universe also only the most common things that are in the universe. The suns and stars are made up of hydrogens and heliums. And so the vast majority of atoms in the universe still are hydrogen.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“A hydrogen and an oxygen, and you burn them and you combine them into water, there's a change in mass. Now, that change per atom and per molecule is actually so small that it's extremely hard to measure, but it's still there. And that's the energy that is released. And you can quantify that. We use units of electron volts as a unit of what is the energy in atomic processes or chemical processes.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“Equals MC squared is a fundamental relationship that a patent clerk, Einstein, discovered and unlocked an entire new realm of physics and engineering and has shown us atomic physics, what happens inside the nucleus, and unlocked our understanding of the universe and paved the way for many of the physics advancements that came after that we think about mass as these particles, but in reality also at the same time their energy and there's a direct quantitative relationship between how much energy is in all of that mass. And in fact, all of the energy that is released even by atomic physics, certainly in atomic reactions, is equals mc squared. And that I think most people have heard of and are used to, but also in chemistry and in chemical bonds that in those chemical bonds there is a change in mass when you take”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“I think about, and I look at that process in stars, in that our star is fundamentally an early stage star that's burning just hydrogens. But when it burns and does fusion, those hydrogens combine into heliums and later stage stars can then burn those heliums. And they can fuse those together to form even heavier elements and carbons. And those carbons can fuse together and form heavier elements. And that whole stellar process is something that inspires us at helion to think about what our fusion fuels, not just the simplest ones, but more advanced fusion fuels that we see in stars throughout the universe. I want to say, so first, maybe zooming out to the biggest possible picture. If we look across hundreds of millions, billions of years and all the my opinion,”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“Going from the lightest elements hydrogen to the heaviest elements, those uranium, plutonium, and others. And fusion happens up to iron. Iron is the magical point in between where lighter elements than iron fuse together and heavier elements fizz or are fissile and break apart and release energy.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“You're taking the heaviest elements in the universe, uranium, plutonium, things that are so heavy and have so many internal protons and neutrons and electrons that they're barely held together at all. They're fundamentally unstable or radioactive. And those elements are very close to falling apart. And as they do that, if you take a uranium-235 or a plutonium-239 nucleus and you add something new, usually it's a neutron, a subatomic particle that's uncharged, that unstable, that very large nuclei will then break into pieces. Many pieces, a whole spectrum of pieces. But if you add up all of those pieces, they also have slightly less mass than the initial one did, the initial uranium or plutonium. And in that process, again, equals MC squared, a tremendous amount of energy is released. There's a very famous curve in atomic physics fusion or fission looking at the periodic table.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“And helium, and fusing those together to make heavier elements. In that process, as you combine atomic nuclei and form heavier nuclei, those nuclei are slightly lighter than the sum of the parts. And that comes from a lot of the details of quantum mechanics and how those fundamental particles combine and interact. We also talk about the strong nuclear force that holds the atomic nucleuses together as one of the fundamental forces involved in fusion. But that mass defect E equals mc squared, we know from Einstein, is also energy. And so in that process, a tremendous amount of energy is released. And the actual reactions, I think, is a lot more interesting than simply it's a little bit lighter and therefore energy is released. But that's the fundamental process infusion is you're bringing those lightweight atomic nuclei, those isotopes together. Fission is the exact opposite.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“Let's start with a big picture. What is nuclear fusion and maybe what is nuclear fission? Let's lay out the basics. So fusion is what powers the universe. Fusion is what happens in stars and it's where the vast amount of energy that even that we use today here on Earth comes from the process of fusion. It also is what powers plants and those plants become oil and those become fossil fuels that then powers the rest of human civilization for the last hundred years. And so fusion really underpins a lot of what has enabled us as humans to go forward. However, ironically, we don't do it actively here on Earth to make electricity yet. And so fundamentally what fusion is, is taking the most common elements in the universe, hydrogen and lightweight isotopes of hydrogen.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
“Who I believe is on the border of Shopify or at the very least is the ambassador of the technology stack at Shopify utilizes in order to deliver incredible services at scale, low latency. It works, it's stable, huge number of transactions, just the insanity that they have to pull off to know that underpinning it is beautiful code is wonderful to learn. Anyway, sign up for a $1 per month trial period at shopify.com slash lux. That's all lowercase. Go to shopify.com slash Lux to take your business to the next level today. This is Alex Friedman podcast to support it. Please check out our sponsors in the description where you can also find links to contact me, ask questions, give feedback, and so on. And now, dear friends, here's David Curtley.”
2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
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2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
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2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source
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2025-11-17 · Lex Fridman Podcast · #485 – David Kirtley: Nuclear Fusion, Plasma Physics, and the Future of Energy · IDENTIFIED FROM THE TRANSCRIPT · source