Is Cold Fusion impossible?

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And for decades now, physics have been promising to unleash the energy source of the stars. Fusion, the thing that makes our sun glow, but brought down to earth and mastered for our empire. So exciting and so just around the corner. It's been 20 years away for about 80 years now. So if hot fusion isn't just around the corner, is there another way? What if we don't need to replicate the conditions inside the sun? What if we could do it all at room temperature? What is the physics of cold fusion? Is it all just charlatans and nonsense? Or is there real science there? And if not, why is DARPA funding it? We'll dig into all of that today on Daniel and Kelly's Extraordinary Universe. Hello, this is Kelly Wintersmith. I study parasites and space. And in Virginia right now, it is so cold that your fingers fuse to anything you touch that is slightly wet. Hi, I'm Daniel. I'm a particle physicist and my wife's favorite piece of physics is a terrible movie called Cold Fusion, starring Keanu Reeves wearing a University of Chicago sweatshirt. Oh, you know, my favorite movie is Keanu Reeves wearing anything because he's such a cutie. That movie is so bad and so full of plot holes, but Keanu Reeves is great and he looks great in that shirt. And hey, if he makes physicists look good on the screen, I'm all for it. No, I've never seen that particular movie, but I like Keanu Reeves. I don't recommend it. OK, all right, I'll skip that one. But yeah, so today we're talking about Cold Fusion, which I'm excited about because I was under the impression and I'll lay it out there now. My impression is that Cold Fusion is an absolutely never going to work almost on the edge of conspiracy theory kind of thing. And that is my preconceived notion. And when I was looking at your outline, I was like, oh, maybe, maybe I'm going to be wrong. This will be an interesting conversation. And then I was like, you know what, I don't want to ruin it. I'm not going to do my homework. I'm not going to look at this outline anymore. And so I stopped looking at the outline. And so here's what I want to know from you today, Daniel. There are lots of different routes that people talk about for how we might make fusion work. If you had to put your money on one route for how fusion might eventually pan out as a way to run toasters, for example, which route would you guess is the most likely to work? And I'm going to guess it's not Cold Fusion. No, how much of my money am I being forced to invest in fusion in this terrible scenario? All of it. Oh, my gosh. I think Cold Fusion is a dark horse there, and I would not invest all of my family resources in it. So I'd have to go for some variant of hot fusion. I think eventually we will make some kind of magnetized fusion work, something like the Tokamax or Eater. Eventually, I think we will figure that out. So you're betting against the many, many, many lasers all at once. I am betting against. I love those and they're really fun. And I want to flip that switch one time. I imagine this like some really big, heavy red lever you get to pull and it's really satisfying. And then they go zap. And I want to do that. But I don't think that that's the most likely way to make energy. Yeah. Wouldn't it be disappointing if it was just like a normal light switch or something? Or a touchscreen button. You know, I'm all about the tactile buttons. You know, it's going to give that haptic response. Yeah. No, I want it to be a big red button that says lasers and you slam your hand down on it or something. All right. Well, today we're not here to talk about Kelly's fantasies of pushing big red buttons, though I share that with you. Have you ever visited CERN in the control room to have a big red emergency button and it's so tempting when you're on shift, you want to press it. And then in the visitors lounge, they have a mockup of it that you can actually press that like turns lights and makes sounds that it's so fun. That's awesome. But no, I haven't. My daughter has been to CERN, but I have not yet. You should come sometime. Anyway, we're not talking about pressing red buttons today. We are talking about trying to achieve cheap and plentiful energy here on earth via fusion, specifically cold fusion. Is it just a Ponzi scheme? Is it real? Could it ever actually work? That was the question we posed to our listeners who volunteer for this audience participation segment of the podcast. So think about it for a moment. Do you think cold fusion is impossible? Here's what people had to say. Couldn't you select cold fusion as a power source in Sim City? Well, then there you go. I guess it's possible. And to Daniel's credit, you also then get alien invasions. So everybody wins, I guess, except for the Sims. Cold fusions are lie because of physics. It's a thing that we know because we can't do fusion here. I wouldn't know. No, I don't think it's impossible. Only as a plot device in a subpar movie. Nothing is impossible. I say so because I have a deep faith in humanity's ability to grow and progress using the scientific method. I know there was a kerfuffle about this before, but can't sob. I loosely remember hearing that cold fusion might be possible inside a giant gold doughnut. Cold fusion is absolutely possible if you stick your tongue to a flagpole in the dead of winter. I don't believe we should say impossible to anything. Someone someday will figure out how to overcome that hurdle. It probably is, but I'm ever the optimist. If cold brewing coffee is possible, so is cold fusion. I would say never say never. I think hot fusion requires high temperatures the same way my golf game requires a very large number of strokes. If I were better at it, I would need fewer attempts, which is kind of the equivalent of lower temperatures. I suspect that cold fusion is impossible because in order to fuse, the particles have to be moving very quickly, meaning high energy, which means probably hot. I liked only as a plot device in a subpar movie. Does that mean reality is a subpar movie? Oh, I mean, it's a pretty, pretty sub, sub, subpar movie. If so. These were great answers. I love that there are people out there who believe, you know, the optimism. Somebody someday will figure this out. It frustrates me that cold fusion has been sort of polluted by a few scam artists and bad experiences that the public had. So it's seen as a totally disreputable line of research, even though there are some possibilities there, as we'll talk about later. Are we going to talk about those scam artists at some point? Oh, yes, we are. We're going to dig into the conspiracies. OK, good, because I think I've heard about those scam artists mostly. And that that's the news that's gotten to me. All right, so let's let's start at the beginning. What is fusion? Yeah, so fusion is the opposite of fission, right? So fission, what happens in most nuclear reactors that we have really mastered and produces huge amounts of reliable, stable energy for humans on earth is when you take heavy nuclei and you split them up like uranium splits up into smaller, lighter nuclei and produces energy. Fusion is the opposite. That's when you take two light nuclei like hydrogen, the lightest possible thing, just protons and you squeeze them together to make something heavy like helium and then you confuse helium together to make something even heavier. So fusion is when you stick stuff together. And the interesting thing is that when you stick stuff together, it releases energy as long as that stuff is lighter than iron. If it's heavier than iron, then when you break it apart, it releases energy. Basically, moving your nuclei closer to iron always releases energy. Fun, Kelly fact. I memorized the words fusion and fission, like their definitions in reverse initially. And then I was so worried I was going to get it wrong that there was like a solid year there where I would do everything I could to avoid needing to say the words fusion or fission for fear of getting it wrong. And then I finally got it straight in my head, but now I'm going to be worried that I'm going to get it mixed up again. But anyway, it's an episode on fusion, so I'm pretty safe if I say fusion. All right, well, should we have a buzzer if you ever get it wrong? No, no. So most of the time, fusion is hard to do because protons are positively charged and they don't like to be near each other. Like they repel each other very strongly, right? Electromagnetism is a powerful, powerful force. And so making this happen is not easy. And yet it happens a lot like our star is an enormous ball of fusion. People say it's an enormous ball of fire. That's kind of misleading because fire is combustion, which requires oxygen and atmosphere. The sun is not burning in that sense. The sun is fusing. Well, actually. Well, actually. I mean, here, accuracy is our game, right? That's right. That's right. I love when people write in and send us well-actually emails like I sincerely, unironically love that. Please do it. Same. Yes. Yes. So we want to strive for total accuracy here. And so what's happening in the sun is that the sun is mostly protons, right? Mostly hydrogen ions, and those are fusing to make helium. And it's not quite as direct as like two protons make one helium atom because helium also needs neutrons to be stable. Because you just had two protons in the helium nucleus. It wouldn't be stable as protons would bust each other apart because of the strong columbic repulsion there. And so you need neutrons to like buffer them a little bit. So to make one helium nucleus, you need four hydrogen protons. You start with four protons, two of them convert into neutrons, and you end up with helium four, which is two protons and two neutrons. So that's the biggest process in the sun, hydrogen burning. And does that release a lot of energy? That does release a lot of energy. It comes out in terms of gamma rays and there's neutrinos also. This is why the sun is like such a bright source, not just of light, but also of neutrinos. And neutrinos are super cool because the sun is mostly transparent to neutrinos. So you make a neutrino infusion, it flies out of the sun. If you have a neutrino detector, you're seeing that neutrino from inside the sun. The sun is opaque to photons. So it makes photons when it fuses, but those photons are absorbed and they just sort of heat up the sun. And then the reason the sun is bright in the sky, like why we see photons from the sun, it's not because you're seeing photons from the fusion, you're seeing photons because the sun is hot and it's like a black body and it glows. So here's another well actually moment for you. There's this bit of pop side that says like it takes a photon 60,000 years to get from the center of the sun to the surface, which is like, I don't even know what they're trying to calculate there. Photons don't go from the center of the sun to the surface. They just like heat up the sun and then the sun is hot. So it glows the way that like iron in a furnace glows, right? Everything that's made of charged particles and has a temperature glows. So there's your well actually moment. We got to have a button for that, too, or at least a little like ticker thing to keep track. Well, actually. OK, and so when I first started hearing about this, I felt a little confused about how you go from that fact to running a toaster. And so could you like make the little jump there for us? Oh, yeah. So fusion releases that energy, right, in terms of photons or neutrons or gamma rays, all sorts of stuff. And then you got to capture it. So if you wanted to build a device that would power your toaster, you need to capture that energy and turn it into electricity, right? And so this is actually a big puzzle for fusion, for like even hot fusion. Even if we got like fusion to work in some of the technologies we're going to talk about later, people have not spent a lot of time or enough time thinking about exactly how to transform that gamma ray or that neutron into Kelly's toast. This is important. Yeah. So that's a hard problem. We'll get to that in just a minute. First, we have to understand the difference between the fusion reaction that happens in the sun and the fusion reactions that we're trying to do here on earth, which are slightly different. And the reason is that fusion is really hard to make happen. Like in order to get two protons to fuse together, you have to squeeze them really hard because they don't want to be together. So essentially, fusion requires high density and high temperature. You got to get those protons going really fast and you need a lot of them near each other. And even still in the sun, fusion is rare. It's not like fusion is happening all the time. Fusion is not like a fire, which will rapidly consume all of its fuel. Even in the sun with very high temperatures and very high density, fusion is rare, which is why the sun is going to last for billions and billions of years, right? It doesn't just like all burn up in an afternoon. And the rate of fusion is very nonlinear with temperature. So like the hotter the star is, the easier it is for it to make fusion happen. The denser and the hotter it is. And so bigger stars, which are hotter and denser at their core, have much more fusion happening at their core. So like twice the temperature doesn't mean twice the fusion. It's like four times the fusion. It's something nonlinear. And so this is why really big stars burn up much faster than really small stars. Because really small stars just have a little itty bit of fusion. They're barely fusing, whereas big stars have a much larger fraction of their fuel actually turning into fusion. I guess I had assumed. I mean, I knew that. But I guess I still assumed that fusion in our sun wasn't rare. I guess I still assumed it was happening pretty darn often. No, if you're a proton in the center of the sun, you can go for billions of years without fusing with anybody. Whoa, lonely. Exactly. It's like Daniel wandering around a party and nobody will talk to him. Oh, I would talk to you, Daniel. I would talk people. I bet there's lots of people wanting to talk to Daniel at parties. And this is a self-sustaining process, right? Because the heat from fusion keeps the sun hot, keeps the core hot. And this is what we call ignition. When the conditions created by fusion make it favorable for fusion. And this is exactly what we want to achieve here on earth, right? We want to have fusion not just like once or twice, but we want fusion to happen often enough that the heat produced by fusion. Heats up the whole system and it makes fusion more likely. And then it just runs on its own. That's what we call ignition. Sort of like the way at a campfire, you don't have to burn every individual stick one at a time, right? Once sticks that's the next one on fire, which sets the next one on fire. It's a chain reaction. What is the other word that they're trying to achieve? Brake even. Brake even, yeah, exactly. It costs energy to get this thing going, right? You got to heat this thing up. You got to start it. And so you got to put in a huge amount of energy to warm this plasma up. To create these conditions. And so what they want is that you get more energy out than you put in. Obviously, otherwise, why are you even building this reactor? OK, so we've hit ignition, but hitting break even is much harder. So that's a little complicated. We'll talk about it in a minute. There's two ways to do fusion. There's the lasers and the magnets and the lasers claim to have achieved ignition, which is cool. Magnetized fusion, which has like the plasma, has not yet achieved ignition. But neither of them have achieved break even where they're generating more energy than they put in. And there's always some like accounting fuzziness there, like which energy do you account? Do you count just the energy that directly landed on the fuel? Or do you count like all the energy needed to run the whole system? We'll get there. But here on Earth, we're not trying to replicate exactly the same reaction that happens in the sun, because that requires really high density and really high temperatures. And so here on Earth, we try to fuse deuterium and tritium, which are particular isotopes of hydrogen. So deuterium is a proton plus a neutron and tritium is a proton plus two neutrons. And so these are advantageous because fusion can happen at a lower temperature for deuterium and tritium than they can for just like pure protons. So those are the ones that we're trying to achieve here on Earth. And you led an absolutely fascinating episode on whether or not we have enough deuterium and tritium on Earth to be able to power the whole Earth using fusion. So listeners should go back and listen to that again, because I remember thinking that that was like totally fascinating, all kinds of stuff that I didn't know before. So I'm going to hit the Daniel is awesome button. Daniel is awesome. And I love that we're making a bunch of work for our amazing audio engineer, because I think every time we've mentioned a button, our audio engineer probably is going to come up with a different button sound. Thanks, Matt. Very cool. And so to answer the question you asked earlier, like how do we use this energy and actually turn it into toast? Well, it depends a lot on the fuel that we're using. Like, for example, if you have helium three, then your fusion doesn't produce neutrons. And so the output of the reaction depends on exactly the fusion you're making. The reactions we're making in like magnetized fusion do tend to produce a lot of neutrons. And so people are working on like, how do you take these neutrons and turn them into electricity? And the idea is to have like a lithium blanket, like to wrap your reactor in lithium. And because what happens when you hit the lithium blanket with these high speed neutrons is it turns the lithium into tritium, which is fuel for your reactor. Plus a bunch of photons, which are basically heat, which then you can use to heat up steam and turn a turbine and create electricity for your toast. Oh, yeah. And I hope there's avocado on that. Yes. And maybe we can even grow those avocados using heat lamps powered by the fusion. And when we get back, we're going to go into more detail about how exactly we are trying to do hot fusion back here on Earth. The people of Britain love their fancy blenders. They bought loads of them. And luckily, if they bought them with Barkley card, they earned rewards. In fact, they'll earn rewards on all their eligible purchases. What you buy is your business. Giving you rewards on purchases is ours. Barkley card back in your future. 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And we're back. And we are talking about ways that we do hot fusion because we don't have the benefit of being as hot as the sun here on Earth. And actually, that's probably great because I really like being alive. And so, Daniel, how do we try doing fusion here on the Earth? So one strategy for the hot form of fusion is to try to replicate the sun as much as possible, right? So, Daniel, how do we try doing fusion here on the Earth? So one strategy for the hot form of fusion is to try to replicate the sun as much as possible, right? So, unfortunately, we don't have the sun's massive gravity, which self contains the fusion reaction over there in the center of the solar system. So instead, we try to use magnets. Essentially, the strategy is make a little magnetic bottle, try to contain the reaction because the reaction would be so hot that like any other device you put it in would melt it. So you need some way to hold it together kind of without touching it. And so a magnetic bottle is very cool. And a magnetic bottle works because the plasma you need for fusion is charged, right? You take a gas, you heat it up, it becomes charged particles. And now you have another way to control those particles because you can push and pull on them with electromagnetic fields. So if you build magnetic fields in such a way that charged particles are always bent sort of the way they are at a super collider, then they just zoom around in a circle. And so the magnetic fields of a tokamak create these helical paths that keep the plasma from hitting the walls. Instead, they spiral around. And so you get this doughnut shaped chamber where the plasma zooms around really high temperature, but it's also contained and so it maintains its density. I kind of love the idea that like I still think about magnets as like a thing that kids play with, you know, like a kid's toy. But it does also end up being the case that like if you can create the most amazing magnets on Earth, you can probably create the cleanest power source that would like save the planet. And I think that's kind of awesome. Yeah, if you could build super powerful magnets, not only could you make fusion much easier, but particle physics would be much easier. We are like limited by the strength of our magnets. Our magnets were a thousand times stronger than we would need huge tunnels, right? And so you would learn so much about the universe if you invented amazing magnets. So, yeah, somebody get on that. Yeah. Remember the most powerful magnets on Earth are the explosive kind. Oh, that's right. The ones where they like blow them up. But yeah, that won't work for regular fusion power. That's not going to help my avocado toast. But the theme here is somehow you got to get your protons to fuse. And the way you do is by getting them close together, which is hard to do. And so the strategy for magnetic fusion is squeeze them, get them hot and get them dense. And that's hard to do here on Earth. And so we do by squeezing our plasma with magnetic fields. And the goal here is to get the plasma to last a long time. If you can get it stable and you can get it zooming around, then those protons will bounce into each other because they have lots of opportunities. And then eventually they will fuse and they will produce energy and you'll reach ignition and then it'll be hot and other protons will fuse. And Kelly will get her toast. OK, so you told me that fusion doesn't even happen that often in the sun, that you could have a proton live for like a billion years without fusing. And so now I'm feeling way more negative about our prospects for fusion here on Earth because that seems crazy. And so our plasma needs to be like hotter and more dense than the sun to have a chance for this to work. Those are those are long odds. No, it doesn't have to be hotter or denser than the sun, because remember, we're going for an easier kind of fusion. Deuterium fusion can be colder. That's right. Yeah, exactly. But the challenge here really is keeping the plasma going because plasma is a bunch of really hot particles and they're going really, really fast. And it's unstable. Like, yes, you have magnetic fields, but these things are a gas with magnetic charges and like gases already have turbulence in them. Now you add electric magnetic fields internal to them. And the magnetic fields are trying to control the particles. A little instability very rapidly turns into a big instability. And so getting a tokamak to build a plasma and keep it going has been the big challenge. The record I've seen is twenty two minutes is the longest I've ever had a stable plasma, which is amazing, because I actually did plasma research. One of my first experiences back when I was in college and back then it was like less than a minute. So to see that progress is encouraging. Yeah, that's awesome. And this is basically the leading form of fusion research. There's a huge project called Eater, which is being built in France, which plans for its first plasma in the mid 2030s, eventually a power plant in the mid 2050s. It's costing like billions and billions. So the plan is make it work, demonstrate, actually can produce energy and then somehow figure out how to shrink the costs. But there's also a lot of exciting private companies jumping into this area. This company called Commonwealth Fusion. And folks are trying exciting ways to sort of bring the scale down, you know, lasers, plus plasma, all sorts of crazy ideas, which are a lot of fun. So there's a possibility that like a fusion startup might crack this problem before the sort of big government project. I'm rooting for him. No, Commonwealth Fusion. The other approach for getting protons together is not to go for time, but to go for increased density. So this is a laser approach and it's called inertial confinement. Rather than getting the conditions you need for plasma and having them last for long enough that the protons fuse, just go for like really high density. Very, very briefly. And the idea here is you have like a little pellet of fuel and you zap it on all sides with a laser, which explodes the outside of it and implodes the inside. Right. So it's like a little compression way that shoots down towards the core of this little pellet. And then at its density, remember, fusion really depends on the density and the temperature. So now fusion happens really fast in the core after like 30 nanoseconds of compression. It goes from like the density of water to like 100 times the density of lead. And the fusion happens faster than this pellet can blow itself apart. It's really incredible. Wow. And then that would just happen over and over and over again. And you would collect. It happens once, right? You zap this pellet, you get a little burst of fusion and then it's done. So in that sense, they've achieved the ignition that like the pellet has used itself up, but then you got to start all over again with a new pellet, right? And so this is the real challenge is like you need like a production chain of all of these pellets. You have to account for the energy you spent building these pellets in your accounting of like, are we getting output? And you got to start over and over again. So it's like a series of these little mini reactions. Yeah. So like if you were going to have a power plant, you'd have to like over and over again, be like, and collecting that sounds like it would be complicated. That's actually what the laser sound like. Have you been there? It's incredible, Kelly. No, I'm just really smart. So the current leading edge here is the National Ignition Facility has 192 lasers and it's been doing really, really well. And this year in 2026, they reached a gain of 4.13, which means the energy that came out relative to the energy that they put in. But there's a couple of big asterisks there. Asterisk number one is that's not energy they capture. That's just like theoretically energy produced. Some of which would be hard to capture and some of which easier to capture. So they're definitely not getting all of it. There's going to be some efficiency factor in front of the energy that comes out. And they don't really account for all the energy they put in. They account for all the energy that landed on the target and was absorbed. Right. Not all the energy they spent producing that energy, some of which landed on the target. So it's like you have a tiny pixie cup and you empty the swimming pool on top of it. And then you only counted the water that landed in the cup. It's like, all right, yeah, but the energy required to run the lasers is like more than 100 times the energy that's delivered on the target. So, you know, there's some nice accounting here. And I'm all for salesmanship and science, but also let's be clear. They're not producing energy. All right, we're not we're not ready to make our toast using this method yet. Exactly. And so both of these are trying to do the same thing, which is squeeze protons together. How do you get protons close enough that they will fuse? So either magnets or initial confinement with lasers. Both of those are trying to do the same thing. And both of those require a lot of heat, right? And so naturally, people have wondered for a long time, is it possible to do fusion without that heat? Can we have some other way to squeeze protons together at room temperature? And that's the promise. That's the dream of cold fusion. And cold fusion is not just a silly movie starring Keanu Reeves or a scam from the 80s. It's a real area of research. And there are some possibilities here. Oh, man, I imagine if you are studying cold fusion, you probably get a lot of a lot of people who are skeptical. OK, all right, so let's let's dig into the science here. OK, so it's true. Cold fusion gets a lot of flak. And I've heard it described as confusion instead of cold fusion. But confusion. Yeah, exactly. All right, so I'm guessing we're not talking about deuterium and tritium anymore. No, we're not. We're just talking about wasting of protons closer together at room temperature. So one idea is to use muons. So the idea is that if you take a hydrogen atom and you take off the electron and you replace it with a muon, then the orbit of the muon is going to be smaller than the electrons orbit. And that means essentially the atom is closer. And so you can get these things closer together. So protons with muons around them are electrically neutral, so they get close to each other. And the muons are close to the protons. And so that can effectively get the protons closer together. And you still get the same amount of power out. You still get the same amount of power out. And the reason that muons get closer to the protons and the electrons is that muons are a much higher mass. They're like 200 times the mass of the electron. And the radius of the lowest energy level depends on the mass. And don't think about these things in terms of orbits, because orbits are misleading. You know, this is a quantum object in the lowest stationary state, but still there's a distribution of expected radii there. And it depends on the mass of the particle. So muons get much closer to the protons because they are heavier. And this is actually something that's pretty well established. Like you can make muonic hydrogen. You can squeeze these things together. In the 70s and 80s, they did these experiments and you get fusion and you get energy out. So why not do that? Well, it's hot. Wouldn't that make everything work better? Well, the problem is if you make this hot, then the muons are no longer bound to the protons, right? You get plasma and then you're back to the same situation. So that actually only works at lower temperature when the muons are low energy and they're bound to the protons. Right? OK. So you might be wondering, why aren't we all eating muon toast right now? Right. Well, I'm not listening to this podcast powered by muonic fusion. This Daniel says they've made this work. And the answer is the same as sort of laser fusion. It works, but it doesn't produce energy because it costs a lot of energy to make muons. Muenons are not something you can find around the way you can find protons. Protons are just hydrogen. Hydrogen is the most abundant thing in the universe. It's literally all around us. It's not hard to find hydrogen. And so making a hydrogen source is not hard, although, as we said earlier, for like magnetic fusion, you actually need tritium, which is harder to find. Anyway, muons are not everywhere. You got to make them and you got to build these muonic hydrogen essentially one at a time and put them together. And so nobody's cracked that puzzle. Like, how do we make enough muonic hydrogen cheap enough so we can actually recoup some of this energy and make money? And there are companies. There's a company called Accelera and Fusion that's working on making high efficiency muon sources and dense fusion cells. And they've claimed like hundreds of hours of continuous fusion in their prototypes. But they still haven't cracked the puzzle of making it produce more energy than it costs to build the fuel. Wow. Because if you're spending a lot of money and energy making the fuel, then, you know, you're not actually producing energy. You're losing it. OK, so definitely not conspiracy theory, but not making toast efficiently. Exactly. Yeah. And this is like not a huge research effort, but there are definitely people working on this. It's the kind of thing where like one big breakthrough could really change the game for sure. So, you know, cold fusion is a legitimate area of research, especially in the muonic direction. OK, but this isn't the end of the outline. So I'm guessing that means there's other ways to do cold fusion. Oh, yes, there are. So let's take a break. And when we come back, let's talk a little bit more about the history of cold fusion and how it got its bad name. OK, and we're back. And as we mentioned at the top of the show, Kelly thought cold fusion was like conspiracy level bad science, which now she feels real. Well, and she being me. Now, I feel really bad about because it turns out there are actually people studying cold fusion and now I feel like a jerk. So, Daniel, how did cold fusion end up getting such a bad name? Well, there's a famous 1989 experiment that claimed to have achieved energy production. And they didn't use muon. They used another approach, which is again a legitimate concept. And this is using palladium. So palladium is just an element and it forms a crystal and has this really weird property that it will absorb hydrogen very happily, like a lot of hydrogen. If you have like a cubic centimeter of palladium, it can absorb 900 times that volume of hydrogen into that crystal. Wow. It like loves packing in the hydrogen, which is weird. And chemistry nerds would be like, yeah, cool. This is fascinating. But from a physics point of view, this is important because this brings protons together, right? It like holds them together. The whole goal of fusion is like bring protons together in some way, either make them hot so they overcome the colombic barrier or compress them with inertial confinement fusion or make them neutral and bring them close with muons. Palladium says, hey, I can bring protons together. No problem. So for like more than 100 years, people have thought this might be a way to achieve fusion at room temperatures. Just jam a bunch of protons into your palladium crystal and see what happens. And there's actually an experiment in the 1920s. Panette and Peters claim to have achieved fusion, cold fusion, using palladium later. They had to retract these results because they couldn't be repeated. But there's like a history of overblown cold fusion claims that go back more than a century. But who are Panette and Peters? Were they like serious physicists or were they just like, what do you got to tell me more than that? Were they just dinguses who didn't like collect their data well or were they trying to like trick everybody? These were real Austrian scientists. And I think they were doing careful work. Later, they retracted their own report because they realized they didn't understand the background of what they were measuring from the air. They were turning hydrogen to helium, right? And they weren't measuring the heat output. They were just measuring the helium and they mismeasured essentially how much helium there was in the air. And so it turns out the air was just it was just naturally occurring helium. They were measuring so like pretty big oops, but not scam artists, as far as I know. OK, all right. Good on them for retracting their own paper. We all make mistakes sometimes. Sorry, Panette and Peters. And then a few years later, a Swedish scientist, John Trangberg, was trying to use palladium also and he applied for a patent based on his efforts. But because of Panette and Peters' retraction, nobody was going to believe in cold fusion. And so his patent application was denied. Oh, yeah. What, but had he actually made his measurements correctly? Or should his patent application have been denied? Because there was no good science to back it up. Well, it turns out he was doing work which is very similar to the work that was done in 1989, where cold fusion became famous. So this is the work of Fleischmann and Ponds, and they used a palladium electrode and deuterium. And the idea is to electrolysis of heavy water. So you have the palladium lattice and deuterium. And deuterium is just that isotope of hydrogen, right? And so you force the hydrogen into the palladium lattice and then you put it under a current. So that's why it's an electrode. And it makes these very high densities. And maybe that deuterium can overcome that columbic barrier. That's the idea. So this is what Ponds and Fleischmann did in 1989. They had this heavy water, which means water with deuterium in it. So the deuterium is there to be absorbed into the lattice. And then they run the current. And what they claim was to see huge spikes in the heat produced. So unlike Panthopeters, they weren't measuring the helium. They were looking for the heat. And they calculated like how much heat could potentially be produced by any chemical reaction they're aware of. And this was much more heat than anything they could expect from chemistry. So they're like, wow, look at this, we have an experiment which is fusing and producing heat. And yet it's running at room temperature. OK, well, so if it's if it couldn't be explained by chemistry, I guess they're saying that then it's explained by physics. But aren't physics isn't physics and chemistry like, you know, like. It's kind of the same thing, isn't it? You know, you know, I see what you mean by chemistry. I mean, like any non fusion process, right? OK, OK, because you expect you have like heavy water here, you have electricity. You got some stuff is going to happen and you can get heat produced. But we're talking about heat that could not be produced by anything other than fusion. OK. And so these guys went out with the story and University of Utah, where they were working, was very excited. And they put out a press release and it got a lot of coverage. And for a moment, everybody thought, oh, wow, maybe cold fusion has been achieved. And so other labs in the United States very quickly went to replicate these results, because as we talked about in our episode about how science works, it's not just like peer review where you like read the article and say, does this make any sense? But the gold standard for science really is replication. Can other people independently in a different laboratory would like slightly different assumptions and different details and like different temperatures in the outside and you're in New Jersey instead of in Utah? If this is real physics, it should happen everywhere. But no replication attempts succeeded. There are a couple where people are like, oh, wait, maybe no. And so nobody could reproduce these results. But of course, this is still a big deal. Cold fusion is like a very exciting and the claims are very strong. So the Department of Energy put together a whole panel to review this in detail, like what is going on? They studied this for a long time and they found that, like on one hand, nobody could reproduce these results, like all the experiments that tried to reproduce this setup and the conditions exactly. None of them saw these heat flashes and the guys who worked on the theory couldn't get the calculations to support what these guys were claiming. Like even in theory, you shouldn't get enough fusion to produce really any significant heat in this setup. And so the whole thing sort of fell apart and it was a tragedy because they got a lot of press and so a lot of the public thought, wow, this is the wave of the future. And then we discovered, oh, it turns out it's not real. So in the earlier case, it sounds like it was a measurement error. They didn't measure something that they should have. But here it sounds like they are measuring something that didn't exist, like heat that nobody else is finding. But surely they must have expected that people were going to try this and then would also not find the heat. And so what what what happened? Did they like not account for the lighter that someone was holding underneath the device? Like what is what's going on here? It's a good question. The answer comes down to chemistry is really hard. And effectively, they didn't correctly calculate how much heat could be produced by non fusion chemistry effects. And it turns out there's more heat that can be produced by chemistry in this situation than they expected. And this led to them to underestimate the basically the chemistry contribution and to attribute the rest of this to fusion. Well, if the answer is chemistry is really hard, then they have my sympathy. So I'm all right, it's poor guys. Yeah, exactly. On the other hand, check your work before you make a huge read or you release a huge result. Yeah, exactly. And, you know, they never saw like the smoking gun of fusion. They saw heat produced, but they also should have seen like neutrons produced, but they didn't. So it's not like they had a unique setup and it was doing cold fusion and nobody else was replicated because of some detail of their experiment. It just didn't even coherently make sense. And digging into it later, people discovered like the way they calibrated their device and the way they were calculating what they expected from non fusion sources was just wrong. And so that's too bad. But, you know, there was still a lot of excitement about this. And the ponds and flashmen didn't have any more support in the United States. There was excitement around the world. And these guys got like 10 million dollar piles of money from the government in France or in Japan to go do their research and follow up, which I think is great. Like, you know, at the time, maybe there was some other way you could do it. Maybe they were on the right track. Like this definitely is a prospect. But unfortunately, they never achieved any results that were useful at all. Bummer. Yeah. All right. And but there are some people who still had the guts to push forward, even though the field had sort of gotten a bad name at that point. There are still people working on this stuff. Google recently had a 10 million dollar multi-year project to test some of these things. They're like, let's do this rigorously. That's really calibrate our calorimeters. Let's really understand the chemistry. And in 2019, they published a paper in Nature saying there was no evidence of cold fusion, but they did improve their experimental techniques. And they were able to understand how you would measure it if it was there. And so it showed that like you can do careful science here, although there are still a lot of challenges. There's still work happening in Japan and in Italy. There's private companies working on this kind of stuff. Other people exploring. So there are definitely people working on this. And just last year, I saw a call from DARPA for grant proposals about cold fusion. Oh, great. You know, like DARPA is famous for being out there and like funding crazy things. So there's definitely like active interest and people are working on it. And if you have a good idea, there is money for it. But there's also the dark side of cold fusion, you know, which is the conspiracy theories. There is some segment of folks out there pushing a story that Ponds and Fleischmann did achieve cold fusion, that it was real. And it was for some reasons that never made sense to me, covered up by the government. I think the story is like the hot fusion folks were getting a lot of money and the cold fusion would threaten that. And so the hot fusion people had a conflict of interest and they were criticizing cold fusion because it challenged the mainstream narrative about hot fusion, et cetera, et cetera. And therefore it was pushed aside. And if you're working on cold fusion, nobody would take you seriously. And, you know, the real story is like, no, there was money for cold fusion. There is money for cold fusion. If you have an idea, people are interested. There's private money, there's government money. There's definitely people looking into it. And Ponds and Fleischmann's work was analyzed. It was they tried to replicate it. They tried to understand it was given a fair shake. And yet there's still this conspiracy. There's like whole documentaries out there about like how the results were real and they were ignored by mainstream physics. And it's just this like extension of anti science conspiracy theory nonsense. But, you know, it's pushed by your usual set of grifters. OK, well, let's do that. It's too bad. And so, you know, mainstream science is skeptical about this. Like nobody's ever done this in an effective way. But also people are skeptical about magnetic fusion and inertial confinement fusion, right? Like neither of these have shown that they actually will produce energy in any realistic way. And there's money for both directions. There's definitely more money for hot fusion than there is for cold fusion, because I think it's shown more promise. And there's like at least a theory of how it would work. People are still struggling to understand on the cold fusion side, how in principle you even would make this work. Like it's more than just the engineering challenges. It's like, could you even produce enough energy in theory if you overcame all the engineering challenges? And so there's definitely some obstacles there for cold fusion. But I would say it's not impossible, right? It's a dark course, but it's still possible and there are opportunities there. And people are following up on them and they're getting money for it. So, hooray. And so if you want to make Keanu Reeves look good and make the premise of that movie sound maybe more realistic than, hey, invest in cold fusion or make it work yourself, you could change the world. Daniel Keanu Reeves is doing a fine job looking good on his own. He doesn't need anyone's help. Because, you know, the promise of cold fusion is amazing. If we could achieve cold fusion, then it might be possible to have really small, very safe reactors. You know, you wouldn't have to have a bunch of lasers or a bunch of hot gas. You could miniaturize them. You could have like fusion inside your toaster, not just getting electricity from the grid, from some massive power plant. You could have like tiny little fusion reactors and everything. Instead of batteries, you could have fusion reactors. That would be awesome. You know, your phone can have a fusion reactor in it and basically burn forever. That would be incredible. But we're still far from that. Yeah, that's right. This is a serious science show. Yes, that would be amazing. And and and I am excited that people are working on a lot of this stuff from a lot of different angles, because you never know what's going to end up being the angle that works. And so it's good to have a lot of different brains working in a lot of different ways. Yeah, exactly. And we benefit from a diversity of curiosity and a diversity of optimism. And so get out there, people solve this problem for us. Kelly needs her toast. I do. I do. And I'd like it to be made in a clean way. All right. Thanks everyone for coming along on this latest journey of curiosity. Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We would love to hear from you. We really would. We want to know what questions you have about this extraordinary universe. We want to know your thoughts on recent shows, suggestions for future shows. If you contact us, we will get back to you. We really mean it. We answer every message. Email us at questions at dangleandkelly.org. Or you can find us on social media. We have accounts on X, Instagram, Blue Sky, and on all of those platforms. You can find us at D and K Universe. Don't be shy. Write to us. This is an iHeart podcast. Guaranteed human.