What is laser fusion?

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Speaker 1: Hey, Daniel, I noticed a trend recently that kind of worries me. Oh, what's that? I feel like people are using the word laser to make things sound more signs. You mean, like laser vision correction. I actually think that's legit, isn't it? Well, to be honest, I've been doing this, I think since the seventies. But the deal I saw something that said quit smoking with lasers. I'm not sure about that. What are they zapping exactly? Maybe they zap you every time you smoke a cigarette ouch, or maybe they just zap your wallet. That wouldn't really stop you from smoking, though, wouldn't You wouldn't have any more money to buy cigarettes, but then your wallet would be smoking. Hi am or handmade cartoonists and the co author of Frequently Asked Questions about the Universe. Hi. I'm Daniel. I'm a particle physicist and a professor at UC Irvine, and I've never purposely zapped myself with a laser. Oh, but you've done it accidentally. I try to talk about that. What are you trying to do with a laser? I mean, you are a particle physicist, so I wouldn't put it past you to you know between around with giant lasers. Lasers are a low energy man for me, Lasers like whatever, what I guess nice to a particle collider, a laser is what like a tiny little you know, baby gun pew pew pew. You're like, give me the giant death star ray. But a laser beam is going at the speed of light. That's faster than what your gun is doing. At the large hadron collider, That's true. My accelerated protons would lose a race to lasers. Son, you know, high new and gunfight. You know, the guy with the laser would get to you first. He would fry me one bill a second before I zapp his brain with the proton beam. Yeah, they would have time to, you know, get out of the way. I don't think physics is nearly as exciting as you'd like to imagine. Well, you don't know my imagination, Daniel. Isn't it always high noon at the larger patron collider? This collidering big enough for the two of us. But anyways, welcome to our podcast Daniel and Jorge Explain the Universe, a production of I Heart Radio in which we try to zapp your brain with all of the amazing and incredible things going on in our universe. We heat up your cerebellum a little bit by talking about all the incredible mysteries about the nature of the universe, how it works, how it came together, how we can harness what we've learned to improve our everyday lives. Yeah, because it's a big universe and there's a lot going on in it. There are things out there exploding, sucking stuff into black holes, and also fusing together, taking lots of material out there in space and smushing them all together to make something new. Because the universe is not static, it's incredible. It's dynamic, it's chaotic. There are powerful things going on in the hearts of stars and the collisions of neutron stars, and mysterious things happening in the centers of black holes. And by understanding how those things work, we cannot just reveal the true nature of space and time and the universe itself, we can hope to better our lives down here on Earth. Yeah, and if anything at all, it's entertaining, sort of like a big battle in a Star Wars movie with lots of lasers. It is pretty fun to watch stars collide and imagine what else you could smush together. But as you said, it's interesting to understand things about the universe and know more about that because sometimes we can use that knowledge for our benefit. We can use it to create better medical devices and new procedures and better devices for our phones, and also maybe even in the future, solve all of our energy needs. That's right. Physics and particle physics is not just about abstract understanding of the nature of the universe, although that is a lot of fun, it also gives us the power to solve real world problems, and by understanding how energy flows in the rest of the universe, we can try to learn how to better harness and tap into it here on Earth. Yeah, because I guess humans, you know, use up a lot of energy. You know, we need to charge up our phones, we need to heat our bodies up in the winter, and so we consume a lot of energy. But so far, most of the energy we use sort of comes from pretty sloppy methods. That's right. Most of the energy produced in the universe is via fusion, squeezing together protons at the hearts of sun to release a little bit of energy as they become heavier. Elements, but down here on Earth were mostly doing other stuff like burning fossil fuels or or capturing the Sun's rays. We haven't yet managed to take advantage of the most common, the most prolific, the most amazing process out there. Yeah, it seems like we sort of use mostly chemistry for energy here down on Earth. You know, we combine moll kulls or break apart giant long molecules, and it seems like the universe has have a better idea for maybe a cleaner idea for how to create or release energy, and it's happening all the time in the sun, for example. Many of our techniques have advantages, but all of them have disadvantages. You know, renewable energy is wonderful, but it's not always easy to predict when the sun will shine or when the wind will blow. Even things like fission based nuclear power that we've talked about recently on the podcast can produce a lot of really toxic nuclear waste. So fusion is always been something we've hoped for, something we've strived for as an energy source of the future, but for a long time it's remains stubbornly in the future. Yeah, and it's an almost very elegant way of getting energy, right, Like, you just take two basic protons s mush them together and you get a slightly bigger atom. And it seems like a pretty clean way to get energy. It is, and the fuel that's required, it's not something complicated and nasty like uranium or even thorium you have to dig up from the Earth's crust. Protons are literally everywhere. It's the most common thing in the universe, so we're not going to run out of protons for fuel for fusion, and hardly produces any waste because the byproducts are also light elements, which are not dangerous. So there are so many advantages, so many reasons to hope that we might get fusion to work. It could basically make energy free. Imagine how our society would be transformed if energy cost literally nothing. Yeah, but as you said, fusion is hard to do. I mean, it's done at the center of the Sun, but that's hard to replicate here on Earth. But there is a sort of relatively new way to create fusion, an idea that's been around for a while that has been making a lot of progress lately. You're probably familiar with our attempts to replicate fusion by replicating the conditions at the heart of the sun, heating things up and storing them in magnetic bottles, for example. But that's not the only way to do fusion. We can also take advantage of lasers. So today on the podcast, we'll be tackling the question what is laser fusion and are you sure that's the way to pronounce it? Yeah? I know, right, it's two s. Is it should be laser fuse fusion. That sounds like a French thie restaurant where they what they cook your food with lasers. Yeah, it's new fusion cuisine with lasers and they lace it with thie basil. That sounds pretty good. Actually, yeah, I know. Alright, Suddenly I'm like Mayne, I'll go get some tie for lunch. I love when our jokes on the podcast are actually seriously good business ideas. Somebody out there, I hope is taking it. I'm not sure restaurants are great business ideas, but maybe one with lasers is maybe we should just have a food truck, right, Let's have a Daniel and Horror. Hey, explain the universe food truck where we try out all of these things is an experiment coming soon to a university near you. Mostly we just sell bananas, you know, every day. This special is something different, you know, black hole donuts, or we can use lasers to write the podcast logo on the banana skin. Oh interesting, So the bananas are lazed with lasers, lazier bananas and then it gets peeled also by lasers. Or just your graduated grand students have plenty to do when not putting them to work in the food truck. You gotta you gotta pay them somehow, physics paying the bills. That's true. Maybe a food truck will raise more money than my latest grand application to the National Science Foundation. Actually, you know, the National Science Foundation requires an outreach component. Maybe I should propose a physics based food truck as a way to reach the public. Yeah, yeah, yeah, there you go. But this is an interesting technique and maybe the way of the future. This idea of creating fusion with lasers. This is an idea that's been around for a little while, right, Yeah, this idea has been around almost as long as the other ideas for fusion. Back in the days when people were still really not sure how we could achieve the conditions necessary to squeeze protons together and release their nuclear energy. And I remember when I first heard about it, I thought, that's crazy, that will never work. That's just like throwing lasers at the problem to try to solve it. Isn't throwing lasers at the problem basically physics. I mean, did you use lasers for everything? I can't seem to fall asleep at night? Have you tried lasers that it works in every situation? I mean, like most physics experiments use lasers, right, My goo uses lasers. All these experiments use lasers. Right. Lasers are very cool. They're very clean. They're single frequency source of photons that are all in phase and highly collimated. So they're very powerful because they'd let you touch something really basic about the universe, right, which is that the speed of light is a constant. It's sort of like pure and clean and simple in that way. And also people like them. They're cool, and so it's a nice thing to write in your grand proposal. That doesn't necessarily mean that it solves every problem. Like you know, are your kids fighting? Not? Lasers are the answer, but they could be. Have you tried just give a couple of laser guns and they'll be quiet and entertained for hours, that's right. And when you smell charred flesh, maybe you know you've gone too far. Well, little powered lasers of course, right right, we'll try that in your kids first. But it is an intriguing idea, and that one that's been around for a while and one that maybe people will be surprised to learn is happening right here in the US in California. That's right. We are the world leader in zapping stuff with enormous big lasers. How american is that? But you can't have anybody else be the world leader of laser snapping. There'll be a national security risk, that's true. And actually these huge lasers are not just for studying fusion, are also for making sure that our nuclear weapons are not degrading as they sit on the stockpile. All right, we'll get into that. But as usually, we were wondering how many people out there had heard of laser fusion or knew how it works. So thanks very much to everybody who volunteers to answer these silly questions over the podcast. It's a lot of fun for us and very helpful for the listeners to hear what other people are thinking and if you'd like to participate, please don't be shy. Just right to us. Two questions at Daniel and Jorge dot com. We'd love to hear from you. Think about it for a second. How do you think laser fusion worked? Here's what people had to say. As I understand that laser is light amplification by stimulated emicious radiation, So I suppose that laser fusion can either amplify the laser further or somehow produce energy similar to solar power. I heard about this some lab achieved what was it, some benchmark recently with laser fusion, and it was all over this science news. Laser fusion is when several lasers are all pointed at one small spot containing the hydrogen itoms in that spot and heating them up. The heat causes the hydrogen atoms to move faster and faster, and they eventually crash into each other, merging, creating helium and fusion. Laser fusion is the fusion that is being done that just achieved a new energy level, and the laser provides the energy to help cause the hydrogen items atoms to bond together to form the helium. I have never heard of laser fusion. But if I were to guess, I would guess it's something where you can focus enough lasers um and get the conditions just right to meet the starting conditions of nuclear fusion, and then from there it's kind of a self sustaining process. I have no idea laser fusion. Probably the research this type of fusion for or future clean energy. Alright, a lot of great answers like the one that said it's fusion with lasers basically, and it's not. It's not wrong, right, Nobody thought it was a tie basil restaurant. That's surprising. That means it's a great idea that oh yeah, nobody's had this idea yet. It's fresh fresh laser fusion cuisine. Even better, organic fresh laser fusion cuisine. Yes, lasers to table. That's a very common thing people want. If he's ask something with a laser, is it still organic? Well, I don't know where did the energy that power the laser come from. Interesting from a free range horse on a treadmill. Maybe that's still organic. Free range horse a treadmill, that's your most organic source of energy, A free range horse from the treadmille brain storm I'm just bit balling here. Yes, in that case, it's an organic laser to table restaurant. Yeah all right, yeah, yeah, maybe ethnically questionable unless I guess the horse likes to work out on a treadmill and all the servers have very long beards that are elegantly trimmed with our new laser beard trimming technique. But then how do you power that laser? More horses? More? We need more horses, man, this this business idea is getting more complicated by the second. Maybe we should stick to our core competencies. I think we just need more layers to the spreadsheet. That's always the answer. I see more spreadsheets. Yes, yes, that's always the answer. But anyways, a lot of people seem to have no idea how this works, and some people had not even heard of the idea of laser fusion. I guess it hasn't been on the headlines a lot. Yeah, it doesn't seem to be as popular an idea as the other forms of fusion. And that's why I thought it'd be fun to dig into and to share people the basic ideas, the challenges, and the potential future. All right, well, you talked a little bit about what a laser is. So now let's um start at the basics and talk about what fusion is. So the basics of fusion are fairly simple. You start with two light elements like hydrogen. Take two protons for example. Those are just the nuclei of the hydrogen atom, and squeeze them together. Now, protons are positively charged, right, they had the same positive electric charge, which means they will repel each other the way to electrons would, and so it's not easy to squeeze them together. But if you squeeze them together close enough, then that repulsive charge gets overwhelmed by a new attractive force. The strong force, which only operates over these very short distances. Now pulls these protons together and squeezes them together to make a nucleus, bonds them together into something new. So now you get helium, and in the process you also release some energy. The state of two protons being bound together into a nucleus is lower energy than the protons flying around free m It's interesting to think that, you know, there's all this hydrogen out there in space, floating around here on Earth. There's hydrogen in the air and and and all that, and it has the potential to fuse together, Like it could at any moment fuse together and release a huge amount of energy. But it doesn't because, as you said, there's the electromagnetic force, which kind of keeps everything from squeezing together, keeps everything apart. Yeah, the strong force is so much more powerful than the electromagnetic force, but it typically only operates over very short distances or reasons that we talked about in some of our episodes about gluons and why quarks can't be alone. But if you get those protons close enough, then the gluons that are inside each of them start to talk to each other, and then they realize, hey, we actually do like to hang out next to each other. But it only happens when the protons really get squeezed together, Otherwise they repel each other and they never get close enough to discover this amazing potential they have. Yeah, it's like the strong force is super super duper strong, but it has a very short range, Like it only kicks in when the two protons are super duper close to each other. Yeah, and it's worth thinking for a moment about like why nuclei stick together at all? Right, Why, for example, can you have a lead nucleus with so many positive protons in it, what's holding it together? And it should be blown apart by the electromagnetic repulsive forces. And the answer is, while you can think of a nucleus as a bunch of protons, really those protons are talking to each other. The boundary between the protons is a little bit fuzzy. Each proton technically has no overall color charge from the strong force, but in reality it does leak out a little bit and that's enough to hold them together. So you can sort of think of a nucleus is like a really large bound state of all the quarks and protons inside, sort of grouped into protons, but that boundary becomes a little bit fuzzy once they're inside the nucleus. It's a little bit like your kids, you know, they always run away when you try to hug him. They're repelled by you once you hug him. Once they get close enough, you can grab him in your arms and then hug him and then they hug you back. Right, Yeah, sort of like that. And there's also an analogy in chemistry, right, like hydrogen and oxygen or independent atoms. But if you bring them close enough together you can form a new state water. And the boundary between the hydrogen the oxygen atom is a little bit fuzzy because now, for example, they're sharing an electron, and that's what a chemical bond is. Right here, in the case of the inside of the nucleus, we're talking about not a chemical bond, but a bond from the strong force. But still they're exchanging gluons, so the overlap between the protons is a little bit less crisp. And so that's what fusion is, is getting the protons close enough to take advantage of that and at least some of the energy that they otherwise have. Yeah. Yeah, and then this happens in stars all the time. That's what powers are a son. It's also what happens in nuclear bombs. Yeah, it happens in stars naturally. And that's for example, where all the heavy elements are made, the helium, the neon, the carbon, the oxygen. All this happens through steady progressions of fusion. You confuse more than just hydrogen. You confuse helium together, you confuse carbon together. You confuse things all the way up to iron. And as you said, we have replicated this process here on Earth we understand the physics of it. It's at the heart of our nuclear web. Yeah, and you know, one thing that I've never really repped my head around is the the idea of where does this energy come from? Like when you smosh two protons together, I know that um the end result has a lower energy state and so therefore energy has to be released. Where where does this energy actually come from? So it's like two hydrogen atoms are repelling each other by the electromagnete force, but once they get close enough to each other, the strong force grabs them and squishes them together. But where does the energy come from? Their energy comes from the original arrangement of the protons as separate objects. It costs more energy to build two separate protons than to build a pair of protons together into a nucleus. And you might think like, well, why is that. Let's just due to the complicated nature of the nuclear interaction. You can think about it sort of the other way, Like if you have a helium nucleus, which is like two protons stuck together, it costs energy to break them apart, to take them apart into separate protons. So reversing that taking two separate protons and turning them into a helium nucleus that releases that energy. Core idea there the is that it's just a lower energy state, and that's just due to the way that the quarks and the blue ones like to arrange themselves. Yeah, I know it sort of makes sense logically, but I still sort of wonder where the energy comes from, Like it just comes out of where, like what's getting transformed into energy or like photons that come out the original energy comes from the Big Bang, which is where these protons were ford You know, think about these protons is like a type bundle of springs. They have all this energy stored in them. Where does that energy come from? Well, whatever process made those protons in the very early universe be remember protons last basically forever those protons are flying around. They have that energy already inside them. And then you give them this option when they can relax a little bit. They can like let one of those springs go and hang out with one of their buddies and together it takes less energy for them to be in a stable state. So they can relax some of those springs and release that energy. In terms of very high energy neutrons which fly out during the fusion process. Oh. Interesting, that's a good way to put it. Yeah, Like at the beginning of the universe, protons were made with like maybe three springs holding them together. But once they meet up with another proton and they get close and they're like, hey, we only need you know, four between us or three between us. Let's throw away all these other springs and that's where the energy comes from. Yeah, we're releasing the energy of the Big Bang. That's a pretty cool way to put it. Yeah. And the sun that's pretty cool. Yeah, Like every time you walk outside and you get bathed by sunlight, part of that was that all came from the Big Bang. It's so much more efficient than the chemical processes that we usually rely on. Like, if you had a gram of fuel and you could efficiently use it for fusion, it would release as much energy as eighty thousand tons of oil. It's just mind boggling how much more energy is released in fusion than in burning oil. Whoa you mean, like a gram of hydrogen has as much energy as eighty tons of oil. Eighty thousand tons of oil eight Wow, And it's like freely available here on Earth, right Hydrogen is pretty easy to get relatively Hygroen is everywhere. It's in water, so you can just like takes sea water and split it up and you get hydrogen. I mean that takes a little bit of energy in order to do that, but the energy released from the hydrogen when you use it infusion is much much more When technical detail is that the most efficient fusion comes not from the kind of hydrogen that we find in our water, but comes from hydrogen isotopes like deuterium and tritium. We find that still here on Earth in terms of heavy water. But it's a bit of an overstatement to say you just like take a cup of sea water and all of that is fuel. But you can still find heavy water here on Earth to use for fuel infusion. Right, you have to do something to it, but at the end you sort of get enough energy to do that and also get energy to power your phone. All right, well, let's get into a little bit of the details of how fusion works and how you can use lasers to make it happen. But first let's take a quick break. Right, we are fusing to get other ideas here, we're having a mind meld. We are releasing a lot of energy and knowledge talking about fusion and how we could maybe do it with lasers because that would be I guess cool. It would be pretty cool. Anything with lasers is fun. Yeah, And it'd be nice to have a laser fusion source at the back of your laser based restaurant and barber shop. I mean, if you have lasers anyway, you might as well have like multiple businesses. Yeah, yeah, yeah, and you could uh, I don't know, they do a nice light show in the sky with your meal. Alright. We talked about how to make fusion happen. You're smushing together protons close enough that the strong force takes over, squeezes them together, releases all out of that pent up energy they don't need anymore. And that's the energy we get it from fusion. And that sounds awesome and great, and because hydrogen is relatively easy to get here on Earth, but it's it's hard because it's hard to squish them together that much. Right, You need to get them close in order to make it work. It's sort of like a really hard hole in mini golf. You need to roll the ball like up an incline. If you get it close enough, it'll fall in the hole. But if you just missed by a little bit, it's going to roll off in the wrong direction. So you gotta get these protons to shoot like right at each other really high speeds for this to happen. Otherwise they're just going to veer off in another direction. Wait what what what mini golf? What you mean? Like, um, it's hard to get them to smooth because they are being repelled by the electromenamtic force. And even if they're on a collection course with each other, the two protons, and they're even off by a little bit, then that electromagnetic force is gonna basically get worse and repel them right and veer them off course. In order to make it happen, you have to get really close, just like you've got to get the ball basically into the hole before you get any points anywhere, not exactly run on target, it's just going to roll right off. Imagine like a mini golf hole where the hole is at the top of a volcano. Whoa like a literal volcano, like a mini golf volcano. You know, like the paper michee covered in ast turf, and it's like allow, that'd be a really hard minigolf hole if you put it at the top of a volcano and you have to shoot it from the bottom or you have to climb up either one sounds difficult, but I guess it's sort of like putting two magnets together, right, Like, if you take two magnets and point them in the you know, the two plus sides together, it's really hard to like, you know, get them to touch right exactly, because the forces keep trying to like move into the side. They certainly do. Now, imagine that if you force them really close together, all of a sudden they stepped together and heat it up. That would be pretty incredible, But only when you really got them next to each other. So that's what we're talking about. And in order to make this happen, order to make protons fused together, you've got to get them close to each other. And to do that, essentially, you need to get them going fast enough, and you have to get them very close together, right, And in the sun that happens because of just the amazing gravity and the amazing pressure and density that's inside of the sun, right, that's right. The way fusion scientists think about it is that you need temperature, then city and time and stars solve this problem using gravitational confinement. They basically make a well in space itself and squeeze all that stuff into it, and then fusion happens. Because you've got lots of time and loss of density and really high temperatures. The temperatures were talking about are like a hundred million degrees kelvin is what's necessary to get these protons to fuse right and density. You need enough of them flying around that fast so that every once in a while some of them like crash head on right and fuse together. For example, there is gas in the universe that's a very high temperature, very low density, like the gas between galaxies can be at millions or tens or hundreds of millions of degrees kelvin, but it's very very dilute. So you're not going to get fusion there because protons aren't close enough together. They need to be crowded together and fast in order to get fusion to happen right, And then you need time, I guess also, because you know, these things don't happen all the time, even if they are going fast, and even if there are a lot of them, they still sort of miss each other or veer off core Earth. You need time for the for that one head on collision to happen every once in a while, right, And the goal, of course, is that you get fusion started, and then the energy released by the fusion spreads out and causes more fusion. And this is what physicists call ignition. It's sort of like when you start a campfire. You don't need to continuously start the campfire all evening. You can sit back and relax because the bit that you started ignites the next bit, which ignites the next bit, which ignites the next bit. It's a chain reaction. We want to get that same process started in a fusion reactor, for example, so you can switch it on by pouring in some energy, but then the energy released from the fusion maintains itself, right, And so that's in the Sun and then in here on Earth. We've try to sort of replicate or make those conditions happen, not with gravity, because we don't have the gravity of the Sun, but they try to do it with magnets, basically like a magnetic bottle. So this strategy, which is pretty widely known, it is called magnetic confinement fusion and the idea here is to get a long time is to build a plasma, making it really really hot, to start with a gas of hydrogen heated up, and then keep it confined for a long time using a magnetic bottle. Because remember that a plasma is charged particles. These are protons, so they have a charge, so we can bend their path using a magnet. We can they make a particle go around in a circle. That's what we do with a large hadron collider. We bend the path of particles using magnets, so without ever touching them directly. Because the plasma is super hot, you can try to keep a plasma contained by using magnets to sort of like make a current go around in a circle. Yeah, and there are active projects right there are. There's a big one in Europe called Eater. We've talked about that on the podcast, where they build basically these giant magnetic bottle and they are trying to get fusion going and they've come pretty close to right. There's a long series of these experiments. They're generally called tocamax, and there's sort of like a doughnut and you have like a tube of plasma flowing around inside of them. It's very challenging because plasma is very unstable. It's very hard to keep it flowing in a tube. It likes to break out and going crazy direct actions and interact with itself very powerfully because these are a lot of positively charged particles. So it's very challenging. But they are building Eater in France and they hope that when it's finished it will achieve fusion and actually create energy. But it's you know, it's a decades long project and it seems like it's always two decades away. Yeah, it's been two decades away for like three decades, right, So that's one way to achieve fusion. And it's hard because you're basically trying to create a son and then contain it in a bottle, which is gonna probably try to melt your bottle kind of. Yeah. So you're constantly battling keeping the plasma stable, trying to keep it going for long enough that you can get ignition and then take advantage of that and burn this thing over and over and over again, keep putting in fuel to your hot plasma so you can keep extracting energy. It's really hard, yeah, and so physicists I guess to hedge their beds have been trying another way to create fusion using lasers, all sort of at the same time. Right, these are two parallel paths of research, two totally different communities of folks with different expertise. And so this path using lasers takes a different approach to confinement. Instead of trying to heat a plasma and keep it confined for a long time, they take a different approach, and they say, we don't care about how long it's confined for. Let's just try to get fusion to happen really really fast by getting our fuel to be super duper dense. So this is called inertial confinement fusion. It's like, let's try to squeeze our fuel down and get fusion to happen sort of before it can blow itself up. Interesting, and I guess more philosophically, to like the ones with magnets, you're basically trying to create a son, like an ongoing sun burning sun. But with these laser fusions, it's sort of a different philosophy. It's more like a conveyor belt sun, or like if you take a son and you string it out into a long sort of line right exactly. You would start with like a pellet and you can use lasers and heat it and create fusion, and then you can use up that pellet and then you'd start again from scratch. So as you say, the plasma approach is like let's have a continuously burning plow when we can just chuck in more fuel like a campfire that lasts all night. This is more like setting off a series of small bombs to keep yourself warm, or like more like bullets right, look more like a machine gun kind of exactly. But you know, if you can get enough energy out of these fuel pellets and do this rapidly, then potentially that could work. All right, Well, let's step people through this here. So the ideas to use lasers to create fusion and you do it by using pellets. So talk to us about this. These pellets, like what are they? What are they made out of? So they're made out of the fuel you would need for fusion, you know, like hydrogen in its various isotopes, So they're like ices of deuterium and tritium. Those are isotopes of hydrogen with extra neutrons, and these are the fuels that fuse best and release the best energy. We're talking about really really small drops. You shouldn't be imagining like some guy shoveling a huge fuel pellet in or something. These things wait like milligrams, right, so like ten milligram hydrogen pellets, and they're they're like little tiny ones, right, like maybe like sinally the size of a babe right there are millimeters wide. They're really really small already, And the reason you don't make them bigger is that it's much more difficult to make it bigger to heat it up and have it be stable. Because what you're looking to happen is sort of similar to what happens in a hydrogen bomb, is that you want to compress the fuel. So you have this fuel is hydrogen in this deterium ice, and what you want instead of keeping it hot for a long time is you want to compress it to incredible densities, because fusion happens much more rapidly as density goes up, Like big stars out there in the universe have more dense cores, which is why they get hotter and fusion happens more rapidly. The idea is to somehow compress this pellet to make it really dense at the core, so the fusion is easier to happen and happens more quickly. Right, Well, maybe take a step back here, and you said it's made out of frozen hydrogen or of heavy water. What does that mean You actually have to make like little ice pellets. Yeah, you have little ice pellets because hydrogen by itself at room temperature is just a gas. So you need to cool this down. So you start with deuterium and treatium ices, right, and so like, yeah, this little frozen pellet of fuel at the heart of this enormous facility that's like the size of a football field. That's going to zap it with lasers, right, Because I guess liquid hydrogen maybe people have thought about, but I guess if you keep cooling, hydrogen will turn into ice. Yeah, everything in the universe eventually will cool down into a solid form, including hydrogen. And how do you make these little tiny ice hydrogen pellets? You just order them on Amazon like everything else. Oh yeah, okay, do you buy the molds. I guess you have to buy the molds first. You know, there's a whole industry now in making these things. It's really complicated, and you have to be really precise about it, because you want a very very smooth surface so that when things started happen simultaneously everywhere. So it's very high technology industry, and it's not something that happens for lots of other reasons. So they have to develop this kind of technology specifically for this industry. Makes it extra challenging. What's the name of that ice cream that comes in like little tiny pellets dipping dots, dipping dots? There you go, Is it like dipping dots. Yes, Yes, it's just like dipping dots, exactly. They're basically fusion dots, right. I always wonder how they make those, Maybe use the same technology, it's the same factory, Yeah, exactly. They taste a little kunchier sometimes, you know, and sometimes they mix it up and they actually again like chocolate chip hydrogen fuel, you know, and that's a big disaster. They're cleaning that out for weeks. They taste delicious, but they're a little explosive, I guess. So the idea is that you have these pellets of fuel and I guess, you know, just like anything else, if you squeeze it enough, things will start to fuse together inside of it and so the question is how do you squeeze it. I guess enough so that you get fusion, right, because you can't just like smash it with the hammer because that will just flatten it. You want to squeeze it from all directions. Yeah, So the idea is that use zapp its simultaneously in all directions using a laser, which turns the outer layer of this fuel pellet into a plasma that blows out, of course because it's a plasma, but it also blows in simultaneously and compresses the your or of the pellet. Again, this is the same basic principle of how a hydrogen bomb works. How do you achieve fusion at the core of a hydrogen bomb is that you surround it with a fission bomb, which goes off and compresses the fuel to cause fusion. So that's the same thing that's happening here, except we're not using fission bombs to start this. We're just using lasers to heat the outer shell, which heats up and explodes and compresses the inner part of the fuel pellet. Right, And I think the idea is that you shoot this little pellet with a laser from all directions or at least like six six or seven dement directions right, like, you have giant lasers pointing at it from different directions like up and down, left and right, you know, a little bit of at an angle here and there, and so it's basically getting squished together by all these lasers down to even smaller side. The lasers themselves are not doing the compression. They're heating up the outer layer, and that rapid expansion of that outer layer is then triggering the compression. And in the most modern facilities they have like a hundred and ninety two lasers, which is pretty awesome. A hundred and ninety two lasers, which makes me wonder like about the design process with somebody like, no, we want a thousand twenty four lasers, let's go with four thousand lasers. And they had some compromise that got them down. May they aim for a two hundred, but they run out of money at the very last moment. But the idea is to get this thing heated up on the outside so it compresses it very rapidly. And this compression happens in like, you know, tens of nanoseconds in order to trigger this. And when it's happening. It's a shock wave that's going in, sort of like in a supernova. You know, you have a shock wave going in that's compressing the core, and the velocity of this stuff is like three hundred and fifty kilometers per second compression waves towards the core of this pellet, right right, But I think you skipped a step. Okay, So, um, you have this pellet, you shoot it with lasers, and if you just shoot it with lasers, it'll just heat up. But I think the idea is that you code the pellets with another material. You code it with various types of material that trigger this implosion. It can be like a plastic coating or other kinds of things. You just need something which is going to heat up enough and expand rapidly so that it compresses the internal core of the pellet. What if you don't code it, like what if the lasers just hit the hydrogen directly, the frozen hydrogen directly? What happens. One of the major challenges here is to get a smooth compression, like you're only going to get fusion and very high pressures if it's being squeezed simultaneously from all sides and so a lot of the research they do is to find the best material which heats up sort of smoothly and expands smoothly in order to get that compression. And that's why they prefer plastics, for example, instead of just more hydrogen, because it tends to have this property to remove instabilities. A lot of times, actually they have another step between the laser and the fuel pellet because they don't want the lasers touching the fuel pellet directly because it tends to cause hotspots, which then cause instabilities. So sometimes they surround the pellet with like a gold tube, and the lasers hit the gold tube. The gold tube then heats up and bathes the pellet in very powerful X rays because of its high temper and then not triggers the expansion of the outer core, which then triggers the collapse, which then gets you the fusion I see. So the pellets are really sort of more like Eminem's kind of right. It's like there's a core of a hydrogen field, but then there's a coating of something else, like a hard coating of of something else, and that's what the lasers hit and actually um basically like burn up right ignite. Yeah, there's direct to drive laser fusion where it directly hits the outer layer, and then there's the indirect where you put it in like a little gold tube and you hit the tube itself and then the X rays from that tube hit the outer layer. So there's two different varieties of laser fusion there. And so the idea is that the lasers basically make the candy shell explode, right, because you got all this energy hitting in the candy layer explodes and then that explosion basically comprises the chocolate enough to that then get fusion. Yes, And the ideas that it happened so rapidly that the chocolate doesn't have a chance to blow up, that it fuses before it blows up. What do you mean, like it fuses and then it doesn't blow up then, or what it fuses and it blows up, But the fusion happens faster than the blowing up. If the material is dense enough, then fusion happens much more rapidly. You can get the whole pellette to have a little self sustaining reaction that lasts like a hundred trillions of a second and get fusion to happen before it has time to sort of blow itself up. Because remember, not only does fusion happen more rapidly when the fuel is dense, but also compressed fuel. Much more dense fuel means that it keeps the fusion energy inside. If you have like a little bit of fusion starting at the center and the fuel around it is very, very dense, it's going to absorb that energy and lead to more fusion rather than letting that energy leak out. Oh, I see what you're saying. You're saying, we zapped with the laser, we kick start diffusion, But then you want it to sort of create a chain reaction inside of the eminem before I guess the eminem breaks apart. It's gonna blow up for sure. Like that's definitely the end game. You're gonna be left with a little smoking pile of ash. But you wanted to fuse before it blows up, or you want to fuse as much of the fuel as possible, right, because that's kind of what could happen if you if you don't get a chain reaction, is you'll just get a little bit in the middle of fusing, and then that will blow the rest of the fuel away without igniting or fusing together. You want like the little bit of fusion to ignite more fusion for the rest of the fuel before it all sort of blows apart, exactly. And so the key there is high density, because high density means fusion happens more rapidly and more energy is devoted to making more fusion. So it's that density that they think will lead to the ignition because otherwise you could just heat up a pellet of lower density, but as you say, it would just blow itself up before it fuses. So you get that condition going that chain reaction. You really need the very high density, but you don't need it for very long. So that's the idea behind inertial confinement. Instead of long time confinement like you have in plasmas, you have short time but high density confinement. I guess you're saying that the aminem is big enough and heavy enough that there is time for the chain reaction to form before it all breaks apart, exactly. But this whole thing happens in like hundreds of nanoseconds, right, I see, So by time you mean like a few not a seconds, By a long time you mean a few nine a seconds, But you achieve incredible density. You know, this stuff goes from like the density of water to like a hundred times and the dense is lead, all in a very short amount of time. You mean, like when the outer candy shell explodes and compresses the chocolate down, it's like super compresses it. Yeah, it's super chocolate. Yeah, it's it's laser chocolate will cure your smoking addiction, and then you need to be zapped in a different place to cure your chocolate addiction. Yeah, I think that. I think they have that in plastic surgery. Yes, all right, well that's the basics of how laser fusion works. Let's get into how well it actually works and have people actually created this on Earth? But first let's take another quick break. All right, we're talking about Eminem's. I guess that's the future of energy on our not that you do they have to beat green Eminem's or can they be any color? Does the color of the laser fusion pellets matter? Can you write that in your writer contract? Yeah? I think that that's a topic for the future. It's not yet something that they have explored the flavor of these pellets, but you know, maybe your future dipping dots laser fusion crossover restaurant research topic will explore that, oh, that would be the perfect dessert for our laser fusion restaurant dipping dots. But then we bring lasers to your table and zap them, zap them in your in your mouth, table side lasing. That sounds fantastic. But these are pretty impressive facilities, the ones that try to do this, right, because I mean, it's a tiny two millimeter pellet, but you can imagine like a tiny little ball surrounded by basically like a giant warehouse of lasers, right, because you need not just like one laser, you need a hundred and nine two lasers pointed at this one little tiny pellet. Yeah, and the leading facility for doing this is in California at Lawrence Livermore National Labs. It's called the National Ignition Facility or NIFF, and they started building and turned it on two thousand nine. And as you said, it's enormous. This thing is like the size of a football field, filled with all the optics and the chambers you need to make very high powered lasers, and a lot of them. Yeah. Yeah, I know, I've been there. I got a tour of it one time, Oh did you stick your head in the beam? I did, Yes, that is where I get all my superpowers. So you weren't nearly as funny before that trip, and but now laser funny. But if you're curious, Actually, an interesting fact is that they use this facility in the movie Star Trek, you know, like the reboot by J. J. Abrahms, and when Scotty's down in the engine room and he's say, she kind of take anymore, Captain, they actually filmed it or they feeled a replica of it. And if I have no idea, that's awesome when science makes a cameo in science fiction. So check that and I guess. But we talked about how fusion works and how laser fusion works, and basically you need to zap these little fuel pellets so that they implode and then that creates fusion. But I guess my question is how do you make it sustainable? You know, like give you zab one pellet, the pellet explodes, and then how do you harness that energy. That's a really hard problem and not something that's been worked on very well. That's also true for other kinds of fusion. Remember for magnetic confinement fusion, the energy comes out as very high speed neutrons, and that's difficult because neutrons are not charged, and so capturing the energy from high speed neutrons is tricky. They have these techniques to like surround it with these lipium blankets that can absorb the neutrons and turn into other more accessible forms of energy. The same problem exists here for inertial confinement fusion is that the energy comes out in the form of high speed neutrons, which has to be somehow captured. For a long time, the fusion community has sort of seen that. It's like, well, that's a downstream engineering problem. Will produce the energy in terms of neutrons, and then somebody will figure out how to take advantage of it. Yeah, just a small problem of how do you how do you capture a nuclear bomb. The other problem, of course with neutrons is that if you don't capture them, they make your whole facility radioactive, right, because high speed neutrons will trigger radioactive decay and lots of stuff, and so you're basically blowing up a neutron bomb at the heart of your very expensive, very delicate facility. I think the idea for these laser fusion reactors. Is that not that you suggest that you use have one little pellet, but it's like you have a stream of pellets right Like it's almost like an assembly line of pellets, and the pellets are moving along in the line, and then one of them gets in the you know, the center of all these lasers, explodes, and then it moves on, and then the next one comes in, moves into the middle of the lasers, explodes, and so on. It's on almost like if you like a conveyor line, right like a factory reactor. Yeah, the idea in the future, if we prove that this works and figure out how to make it viable, is to have like several pellets per second. The good news is that these pellets don't take very long diffuse and blow up release their energy, So on principle, you could do a lot of them over time and produce enough energy to be useful. Is sort of the hope and the dream making that actually work has a lot of technical issues. Wait, wait, several pellets per second, Like you're shooting a machine gun of these pellets and they're flying through the middle of the lasers, exploding, and then somehow you're capturing that energy. Yeah, so far our facilities are like you set up one pellet, you spend days tweaking it. Everybody gets set up SIPs her coffee boom, you do an experiment, you analyze it for weeks or months, right, But the dream is to make it reproducible, to make it straightforward, so you could do several per second. Wow. And so the idea isn't you have the stream of pellets going into the middle of the lasers and somehow it releases all this energy and you're capturing somehow that energy because the energy comes out as photons or neutrons. What the energy comes at as high speed neutrons. When you fuse two protons together, you get helium, but you also get neutrons leaving with a lot of energy, and so you have to capture those neutrons and steal their energy somehow, which is tricky. And you don't also want those neutrons to interfere with your lasers or the other targets or anything else. And so it's not a small problem to solve. But you know, we still haven't figured out how to actually make fusion work and these things, and so we're not even really there yet. Boy, it seems like a big part of it, and you know, it sounds like something you might want to be thinking about. Right now. People are thinking about it, but you know, it's not as sexy a question, and it's not the first question. It's that question number four. You gotta answer all the questions to make fusion work and to make it viable and to you know, get to your final goal of providing cheap or free energy for humanity. But we're not even there yet. We're still working on question number one. All right, Well, so then where are we on question number one? Have we achieved fusion and how big of a deal was it? So NIFF turned on in two thousand and nine, and they have achieved fusion. Like they have pellets and they have lasers and they have zapped it and there has been fusion. There has been energy produced in that reaction. They have gotten energy out of those pellets. I mean, they produced the energy. Didn't like use it to charge their phone or anything, but fusion has occurred at the heart of those pellets. So they put a pellet in the middle of the lasers. It exploded, The eminem exploded. So that's it, right, wouldn't that mean that you you get they could get it working, So early on they achieved getting some energy out, and then in two thousand and thirteen it was very exciting because they got more energy out of the fusion than went into the fuel. So they're like bathing this fuel pellet in these X rays from this gold tube that's being zapped by the lasers, right, And how you determine whether it's a success depends a lot on how you're doing the accounting. So the energy that comes out of the pellet was more than the energy that went into the pellet, and that's good news. It's like you started a fire. You released some energy. But there's a huge amount of energy that went into the whole process that was sort of lost along the way that isn't being accounted for, you know, So they haven't reached break even where they're getting more energy out of the whole process than they put into the whole process. For example, there's a lot of energy that went into the gold that never made it into the pellet, and there's a lot of energy in the laser losses and amplifying these lasers is very very inefficient. So in two thirteen they reached a milestone of sorts in that they got more energy out of the pellet than they put into the pellet. They didn't get more energy out of the pellet than they put into the whole process, right, because you also have to account for making that coffee for the physicists too, right, Like that's that's the energy that goes in. Yeah, exactly, you know, and all the dipping dots and stuff. Yeah, all that desserts too. I mean that all count. But I think maybe what's confusing is that this idea that you're not getting enough energy out of it. And I think it goes back to this idea of like how much of the eminem are you actually burning up? I think it's what you're saying, Like they can shoot the pellets with laser and you can get fusion to happen in the middle, But maybe the fusion isn't sustained enough to fuse the whole eminem out. Maybe we all need to open in the middle fuses and then the whole thing breaks apart, in which case you don't get as much energy as you could. Exactly, And what they're trying to do is make the fusion happen a little bit longer inside to use more of the fuel to release more of that energy. And so then they spent a lot of time tweaking it and trying to improve it. You know, they change like the material of the container, this hygrogen deterium container with change to diamond in order to increase the absorbency of the secondary X rays created by this laser burst. They also did all sorts of other stuff like smoothing the surface of the fuel capsule, shrinking the holes in the capsule where they injected, shrinking the holes in the gold cylinder that's surround the capsule to reduce energy loss, making the laser pulse last a little bit longer. They spent years tweaking it, and then in two thousand and twenty one they got a big increase in the energy output, so it's much more than they had in two thousand and thirteen, and they reached up to seventy percent of the break even point, meaning now the energy that's coming out of this little pellet is seventy of all the energy that was required to run the whole process, including you know, powering the lasers and the energy lost due to X rays that wins somewhere else right, because I guess the goal is to basically burn up the entire eminem, right, like use up all the chocolate and the fuel pellet, Like, do you have a sense of how much of it we've been able to get into fusion or is it still only a little bit in the middle, or have we sort of maybe are getting close to using up the whole eminem. We're not getting close to using up the whole eminem. Even these successful chain reactions is still pretty short lived. There, like a hundred trillions of a second, and we get them to go a little bit longer, we'd be able to burn more of the fuel. They think that there's a much higher potential. In principle, you could make this implosion happen the same way all the way around the capsule, and you get higher densities, you get faster fusion, you get to burn more of the stuff. So there's a lot of really small details, these technical hiccups that have prevented them from reaching like the maximum power output, which they think is probably a lot higher than what they've achieved so far. I see there's like even a little imperfection in the pellet, or if maybe one of the lasers is a little bit stronger or off by a little bit. You're saying, like the pellet doesn't compress evenly, like squeezes more on one side, which then I imagine, you know, squeezes things out the other end, and so you don't get this like perfect little compressed ball that's that's ideal for fusion. Yeah, and it's hard to know exactly what's going to work because now we're talking about very high speed, very high temperature, very high pressure conditions. They're difficult for us to solve like with our equations, and also very challenging for us to solve with our computers to like model what should work. You might imagine, why don't the physicists just figure out what the best arrangement is and do that, And we don't know how to figure that out, and so we just have to sort of like tinker and explore and to figure out what might work. So they have these very high speed cameras they used to take pictures of these pellets as they're imploding, trying to figure out exactly what happened. It's a real forefront of research to try to understand high temperature, high pressure conditions. And when you say break even point. I think what you mean is, like, you know, once a pellet explodes, it releases certain amount of energy, but it took a certain amount maybe a more energy to squeeze that pellet, you know, to power all those lasers, to create the pellets, to set it up, and so that even if the pelletics fuses and explodes, it doesn't release as much energy as it took to actually get it to fuse. Right Exactly, if you want to run a power plant, you wanted to produce energy, right, not cost energy. And so if it takes more energy to run your power plant then it's producing then you're not going to make any money. You're not gonna help anybody. And so right now what they're doing is trying to push that output up. And you know there at sev of break even point, which also doesn't even really account for all of the upstream details of how you power all of these lasers and everything. So sometimes this accounting can even be a little bit too optimistic, But I guess the main point is that the energy is there, right like in even in these like two millimeter pellets of how digen fuel, there's you know, eighty thousand tons of oil worth of energy, right, and so like, it's definitely possible in theory that if you if you get to release all of the energy inside of these tiny little pellets, you would have way more energy than what you need to heat up the pellet. Absolutely, the energy is there. They think that they need a factor of ten or more improvement in performance to approach like economically feasible conditions. And that's not even without solving the problem of like how you do this multiple times per second and how you get the energy out just in terms of like theoretical production of the energy. But you're right, it's there, it's harnessed. It's inside these pellets, and you know it's inside me and you, like all the atoms in our bodies have all of this energy stored inside their protons. It's just a question of harnessing it, of creating the right conditions forcing the universe to release all of that energy. Yeah, no, I know my body is full of von ms on any given day. If only I could harness that energy for good And another challenges you have to make these pellets right, and these pellets can't be super duper expensive if you're gonna use many of them. Per second. So people have done calculations to suggest that like each pellet can cost more than a few cents. Otherwise the electricity that comes out would be much more expensive than like solar power. And so to keep it economical, you need to find a way to manufacture these like heavy water pellets that are perfectly smooth for less than ten cents a pop. How much should they cost now? Probably thousands of dollars kind of right, because it's still in the research phase. Yeah, well, you know, they spend billions on this facility. I don't know how many pellets they've made, but it's not a nice number. But I guess if it does show that you can get more energy out of it, and it does replace all of our you know, oil and solar and wind, then it would be a huge industry and probably they would be mass producing these pellets like crazy, exactly, And nobody's really working on figuring out how to make that cheap yet, as you say, if there really was an energy opportunity here, there'd be a huge market and a lot of effort there, and I'm sure people could figure it out because hey, there's lots of smart engineers out there, ones that haven't had their head zapped by a big laser, for example. Maybe they should and they would figure it out. That's been the problem the whole time. Yeah, yeah, Do you need those ideas diffuse together in your head, you know, and then to leak out of a little hole in the back of your head made by the Yeah, so that people can make use of it, you know. But you can always plug it up with a little eminem al Right, Well that's laser fusion. I guess it's a work in progress. You know. It seems super duper difficult and maybe even impossible, but hey, if you get it working, you could solve all of our energy needs for eternity basically, right, or at least until hydrogen runs out in the universe it does end. For a while, maybe twenty years ago, it seemed really promising and really exciting and like we might really make this work. The fact that it hasn't achieved the success that people hoped has put a little bit of damper on the enthusiasm for this. But there's still lots of people out there who think that it's the right way forward. I see people are getting a little miffed at their expectations have been zapped. Yeah, maybe that the dreams are growing up in smoke. Maybe it's zapping their enthusiasm. But good luck to them, and and please keep on working on it because you know the world needs a cleaner and better source of fuel. I mean, you know, we can't sort of keep burning up stuff and in ruining our environment. It's absolutely vital. Let we figure that out, all right. Well, we hope that zapped your curiosity and you learn more about an interesting idea for the future. And maybe some of you listening could be the engineers to the scientists that figure out how to make all of this work. Please get to it. That's right. There's plenty of mysteries out there for you to solve and plenty of impacts for you to make. You hope you enjoyed that. Thanks for joining us, See you next time. Thanks for listening, and remember that Daniel and Jorge Explain the Universe is a production of I Heart Radio. 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