why weren't we pushing towards economic fusion and new materials and new methods of heat extraction and so forth because everybody knew Fusion was 40 years away and now it's four years away the following is a conversation with Dennis white nuclear physicist at MIT and the director of the MIT plasma science infusion center this is the Lex Friedman podcast to support it please check out our sponsors in the description and now dear friends here's Dennis White let's start with a big question what is nuclear fusion is the underlying process that powers the universe so as the name implies it fuses together or brings


together two different elements technically nuclei that come together and if you can push them together close enough that you can trigger essentially a reaction what happens is that the the element typically changes so this means that you change from one element to another chemical element to another underlying what this means is that you change the nuclear structure this rearrangement through equals mc squared releases large amounts of energy so Fusion is the fusing together of lighter elements into heavier elements and when you go through it you say oh look so here are the initial elements typically hydrogen and


they had a particular Mass rest Mass which means just the mass when they're with no kinetic energy and when you look at the product afterwards it has less rest mass and so you go well how is that possible because you have to keep Mass but mass and energy are the same thing which which is what equals mc squared means and the the conversion of this comes into kinetic energy namely energy that you can use in some way and that's what happens in the center of stars so Fusion is literally the reason life is is viable in the universe so Fusion is happening in our sun and what are the elements the elements are hydrogen that are coming together it goes through a


process which just probably gets a little bit too detailed but there's it's a somewhat complex catalyzed process that happens in the center of stars but in the end stars are Big Balls of hydrogen which is the lightest it's the simplest element the lightest element the most abundant element most of the universe is hydrogen and and it's essentially a sequence through which these processes occur that you end up with helium so those are the primary things and the reason for this is because helium has features as a nucleus like the interior part of the atom that is extremely stable and the reason for this


is helium has two protons and two neutrons these are the things that make up nuclei that make up all of us along with electrons and because it has two pairs it's extremely stable and for this reason it when you convert the hydrogen into helium it just wants to stay helium and it wants to release kinetic energy so stars are basically conversion engines of hydrogen into helium and I mean this also tells you why you love Fusion I mean because our sun will last you know 10 billion years approximately that's along the fuel will last but to do that kind of conversion you have to have extremely high temperatures it is one of the


criteria for doing this but it's the easiest one to understand and why is this it's because effectively what this requires is that these hydrogen uh ions or which is really the bare nucleus so they have a positive charge everything has a positive charge of those ones is that to get them to to trigger this reaction they must approach within distances which are like the size of the nucleus itself because the nature in fact what it's really using is something called the strong nuclear force there's four fundamental forces in the universe this is the strongest one but it has a strange property is that it while it's


the strongest force by far it only has impact over distances which are the size of a nucleus so to get put that into what does that mean it's a millionth of a billionth of a meter okay incredibly small distances but because the distances are small and the particles have charge they want to push strongly apart namely they have repulsion that wants to push them apart so it turns when you go through the math of this the average velocity or energy of the particles must be very high to have any significant probability of the reactions happening and so the center of our sun is at about 20 million degrees Celsius and on Earth this means it's one of the


first things we teach you know entering graduate students you can do a quick you can do a quick basically Power Balance and you can you can determine that on Earth that it requires a minimum temperature of about 50 million degrees Celsius on Earth to perform Fusion to get enough Fusion that you would be able to make get energy gain out of it so you can trigger Fusion reactions at lower energy but they become almost vanishingly small at lower temperatures than that first of all let me just link around some crazy ideas so uh one the strong force just stepping out and looking at


all the physics is it weird to you that there's these forces and they're very particular like it operates at a very small distance then gravity operates at a very large distance and and they're all very specific in the standard model describes uh three of those forces extremely well and there's and this is one of them and yeah this is one of them and it's just all kind of works out there's a big part of you that's uh you know an engineer that used to step back and almost look at the philosophy of physics so it's interesting because as a scientist I see the universe through that lens of essentially the interesting


things that we do are through the forces that are get used around those and everything works because of that Richard Feynman had I don't know if you've ever had Richard fine it's a little bit of a tangent but she's never been on the pocket he's never been on the podcast he was unfortunately passed away but wanted like a like a hero to almost all all physicists and then part of it was because of what you said he kind of looked through a different lens at these but typically look like very dry like equations and relationships and he kind of I think he brought out the Wonder of it in some sense right for for those he posited what would be if you


could write down a single not even really a sentence but a single concept that was the most important thing scientifically that we that we knew about that in other words you had only one thing that you could transmit like a future or past generation it was very interesting it was um so it's not what you think it wasn't like oh strong nuclear force or Fusion or something like this and it's very profound which was he was that the reason that matter operates the way that it does is because all matter is made up of individual particles that interact each other through forces that was it so just that atomic theory basically yeah


which is like wow that's like so simple but it's not so simple it's because like who thinks about atoms that they're made of like I I this is a good this is a good question I give to my students how many atoms are in your body like almost no students can answer this but to me that's like a fundamental thing by the way it's about 10 to the 28. out of 28. so that's uh you know trillion or you know million trillion trillion or something like that yes so one thing is to think about the number and the other is to start to really Ponder the fact that it all holds together yeah it all holds together and you're actually that you're more that than you are anything


else yes exactly yeah no I mean there are people who do study such things of the fact that if you look at the for example the ratios between those fundamental forces people have figured out oh if this ratio was different by some Factor like a factor of two or something I was like oh this would all like not work and I look you look at the sun right it's like so it turns out that there are key reactions that if they had slightly lower or probability no star would ever ignite and then life wouldn't be possible it does seem like the universe set things up for us that it's possible to do some cool things but it's challenging so that that keeps it fun


for us yeah yeah that's the way I look at it I mean the you know the Multiverse model is an interesting one uh because there are you know Quantum scientists who look at and figure I was like oh it's like oh yeah like Quantum science perhaps tells us that there are almost an infinite you know variety of other universes but the way that it works probably is it's almost like a form of natural selection it's like well the universes that didn't have the correct or interesting relationships between these forces nothing happens in them so almost by definition the fact that we're having this conversation means that we're in one of the interesting ones by


default yeah one of the somewhat interesting but there's probably super interesting ones we I I tend to think of humans as incredible creatures our brain is is an incredible Computing device but I think we're also extremely cognitively limited I can imagine alien civilizations that are much much much much more intelligent uh in ways we can't even comprehend in terms of their ability to come to construct models of the world and to do physics to do physics and Mathematics I would see it in a slightly different way it's actually it's because we have um we have we have creatures that live


with us on the earth that have cognition right that understand and move through their environment but they they actually see things in a way or they sense things in a way which is so fundamentally different it's really hard like the TR it's the problem is the translation not necessarily intelligence so it's the perception of the world so I have a dog and when I go out and I see my dog like smelling things there's a realization that I have that he sees or senses the world in a way that I can never like I can't understand it because I can't translate my way to this we get little glimpses of this as humans though by the way because there are some parts of it


for example Optical information which comes from light isn't now because we've developed the technology we can actually see things you know I've had I get this you know as a one of my areas of research is spectroscopy so this means the study of light you know and I and I get this quote unquote see things or representation of them from you know the far infrared all the way to like hard hard x-rays which is several orders of magnitude of the of the light intensity but our own human eyes like see a teeny teeny little sliver of this yeah so that even like bees for example see a different place than we do so I don't I I think if you think of there's already


other intelligences like around us in a way in a limited way um because of the way they can communicate but it's like those are already baffling in many ways yeah so if we just focus in on the senses there's already a lot of diversity but there's probably things we're not even considering as possibilities for example uh whatever the heck Consciousness is could actually be a door into understanding some physical phenomena we're not I haven't even begun understanding so just like you said spectroscopy there could be a similar kind of spectrum for Consciousness that we're just like we're like these dumb uh


the descendants of Apes like walking around it sure feels like something to experience the color red but like we don't have it's the same as in the ancient times you experience physics you experience light it's like oh it's bright and you know yeah yeah and you construct kind of uh what's interesting we might actually experience this faster than we thought because we might be building another another kind of intelligence yeah and that that intelligence will explain to us how silly we are there was an email thread going around the professors in my department already of uh so what is it going to look like to figure out if


students have actually written their term papers or it's chat chat GPT um uh it was so as usual as it is where you we tend to be empiricists in my field so of course they were in there like trying to figure out if uh if it could answer like questions for a qualifying exam to get into the PHD program T which was it they didn't do that well at that point but of course this is just the beginning of it so we have some interesting ones to go eventually both the students and the professors will be replaced by Chad GPT yeah and we'll sit on the beach I really recommend you know


this I don't know if you've ever seen them it's called the day the universe changed James Burke he's a science historian based in the UK um he had a had a fairly famous series on on public television called connections I think it was but the one that I really enjoyed was the day the universe changed and the the reason for the title of it was that um he says the universe is what we know and perceive of it so when there's a fundamental insight as to something new the universe for us changes of course the universe from an objective point of view is the same as it was before but for us it has changed so he walks


through these these moments of perception in in in in the history of humanity that like changed what we were right and so as I was thinking about coming to to discuss this you know people see Fusion oh it's still far away or we've been it's been slow progress It's like when my when my godmother was born like people had no idea how Stars worked so you talk about like that day that Insight the universe changed it's like oh this is the I mean and they still didn't understand all the parts of it but you know they basically got it it's like oh because of the because of the understanding of these processes it's


like we unveiled the reason that there can be life in the universe that's probably one of those days the universe changed right yeah and uh remember 1930s yeah it seems like technology is developing faster and faster and faster I tend to think just like with your gbt I think this year might be extremely interesting just with how rapid and how profitable the efforts and artificial intelligence are that just stuff will happen where our whole world is transformed like this and we're there's a shock and then next day you kind of go on and you adjust immediately uh you probably won't have a similar kind of thing with uh nuclear


fusion with energy because there's there's probably going to be an opening ceremony and stuff yes an announcement it'll take months but with uh with digital technology you can just have a immediate transformation of society and then it'll be this gasp and then you kind of adjust like we always do and then you don't even remember just like with the internet and so on how the days were before and how did it worked before right yeah I mean Fusion will be because it's energy it's it's nature is that it will be um and anything that has to do with energy use tends to be a slower transition but they're the most I would argue for some of the most profound


transitions that we make I mean the reason that we can live like this and sit in this building and have this podcast and people around the world is is at its heart is energy use and it's intense energy use that came from the evolution of starting to use intense Energies at the beginning of the Industrial Revolution up to now it's that it's like it's a Bedrock actually of all of these but it doesn't tend to come overnight yeah and some of the most important some of the most amazing Technologies one we don't notice because we take it for granted because it enables this whole thing yeah which is energy which is amazing for how


fundamental it is to our society and way of life is a very poorly understood concept actually just even energy itself people confuse energy sources with energy storage with energy transmission these are different physical phenomena which are very important for so for example you know you buy an electric car and you go oh good I have an emission free car and uh ah but it's like so so why do you say that well it's because if I draw the circle around the car I have electricity and it doesn't emit any anything okay but you plug that into a grid where you follow that wire back there could be a coal power plant or a gas power plant at


the end of that oh really I mean so this isn't like carbon free oh and it's not their fault it's just you know they don't like the car isn't a source of energy the underlying source of energy was the combustion of the fuel back somewhere plus there's also a story of how the raw materials are mined in which parts of the world uh with sort of basic respect or or deep disrespect of human rights that happens in that money so the whole supply chain there's a story there that's deeper than just the particular electric car with a circle around it in the physics or the science of it too is the energy use that it takes to do that digging up which is


also important and all that yeah anyway so yeah we wandered away from Fusion but yes it's beautiful but it's very important actually to in the in the context of this just because you know those of us who work in infusion and these other kinds of um sort of disruptive Energy Technologies it's it's interesting I do think about like what would it what is it going to mean to society to have an energy source that is like this that would be like you know which has which is such completely different characteristics for example you know free unlimited access to the fuel but it has technology


implications so what does this mean geopolitically what does it mean for how we how we distribute wealth within our society it's it's very difficult to know but probably profound yeah we're gonna have to find another reason to start wars uh for instead of resources we've done a pretty good job of that over the course of our histories yeah uh so we talked about the forces of physics and again sticking to the philosophical before we get to the specific technical stuff E equals MC squared you mentioned how amazing is that to you that energy and mass are the same and what does that have to do in your


clear Fusion so it has to do with everything we do it's the fact that energy and mass are equivalent to each other they're just the way we usually comment to it is that they're Just Energy just in different forms can you intuitively understand that yes but it takes a long time I um having for all but usually often I've I teach the um the introductory class for incoming nuclear engineers and and so we put this up as an equation and we go through many iterations of using this uh to how you derive it how you use it and so forth and then you usually in the final exam I would give I would basically take all the equations that


I've used before and I flip it around I basically instead of thinking about energy is equal to mass is sort of mass is equal to energy and I asked the question in a different way and usually about half the students don't get it it takes a while is to get that intuition yeah um so so in the end it's interesting is that this is is actually the source of all free energy because that energy that we're talking about is kinetic energy if it can be transformed from Mass so it turns out even even though we we used equals MC square this is burning coal and and burning gas are and burning wood is actually still equals mc squared the


problem is that you would never know this because the relative change in the mass is incredibly small by the way which comes back to Fusion which is that E equals m c squared okay so what does this mean it tells you that the the amount of energy that is liberated in a particular reaction when you change Mass has to because c squared is that's the speed of light squared it's a large number it's a very large number and it's totally constant everywhere in the universe which is which is another weird thing which is another weird thing and in all rest frames and the actually the relatively stuff gets more difficult conceptually even until you


get through it anyway so you go you go to that and and it's in what that tells you is that it's the relative it's the relative change in the mass we'll tell you about the relative amount of energy that's liberated and this is what makes fusion and you asked about Fusion as well too this is what makes them extraordinary it's because the relative change in the mass is very large as compared to what you get like in a chemical reaction in fact it's about it's about 10 million times larger and that is at the heart of why you use something like Fusion it's because that is a fundamental of nature like you can't beat that so of whatever you do if


you're thinking about and why do I care about this well because Mass is like the fuel right so this means Gathering the resources that it takes to gather a fuel to hold it together to deal with it the environmental impact it would have and fusion will always have 20 million times the amount of energy we lease per reaction that you could have those so this is why you know we consider it the ultimate like environmentally friendly energy source is because of that so is it is it correct to think of mass broadly as a kind of storage of energy yes you mentioned it's environmentally friendly so


nuclear fusion is a source of energy it's cheap Clean safe so easy access to fuel and virtual Unlimited Supply no production of greenhouse gases little radioactive waste produced allegedly uh can you can you sort of elaborate why it's cheap clean and safe I'll start with the easiest one cheap it is not cheap yet because it hasn't been made at a commercial scale right flies when you're having fun yes yeah yeah but yes not yet but we'll talk about it actually we'll we'll come back to that because it it this is cheaper or or a more technically correct term that is economic that it's economically interesting is is really the primary


challenge actually a fusion at this point um but really we can get back to that so what were the other ones you said um so cheap actually when we're talking about cheap we're thinking like asymptotically like if you take it Forward yeah several hundred years uh that's sort of because of how much availability there is of resources to use of the fuel you have the fuel we should separate those two the fuel will all the fuel is already cheap it's basically free right what do you mean by basically free so if if we were to be using fusion um fuel sources to power your and it's like that's all we have is fusion power


plants around and we were doing it the fuel cost per person or something like 10 cents a year it's like it's free okay this is why it's hard to in some ways I think it's hard to understand Fusion because people see this and go oh if the fuel is free this means the energy source is free because we're used to energy sources like this so we you know we spend resources and drill to get gas or oil or we chop wood or we make coal we find coal or these things all right so Fusion this is what makes fusion and it's also um it's not an intermittent renewable energy source like wind and solar so say but this is this makes it hard to


understand so as you're saying the fuel is free why isn't the like why isn't the energy source free and it's because of the necessary Technologies which must be applied to basically recreate the conditions which are in stars in the center of stars in fact so there's only one natural place in the universe that fusion fusion energy occurs that's in the center of stars so that's going to bring a price to it depending on the the cost and sorry the size and complexity of of the technology that's needed to recreate those things and we'll talk about the details of double Technologies and which parts might be expensive today and which parts might be expensive in


200 years exactly it will have a revolution I'm certain of it um so about clean so clean is at its heart what it does is convert it basically converts hydrogen into it's it's it's heavier forms of hydrogen the one the most predominant one that we use on Earth and converts it into helium and some other products but primarily helium is the product that's left behind so helium safe inert gas you know in fact that's actually what our sun is doing is eventually going to extinguish itself because it'll just make so much helium that it doesn't it doesn't do that so in that sense clean because there's no there's no emissions of of carbon or


pollutants that come directly from the combustion of the fuel itself and safe safe we're talking about very high temperatures yeah yeah so this is also the counterintuitive thing so you I told you temperatures which like 50 million degrees or it actually tends to be more like about 100 million degrees is really what we aim for so how can 100 million degrees be safe and it's safe because it is this is so much hotter than anything on Earth where everything on Earth is at around 300 Kelvin you know it's around a few tens of degrees Celsius and what this means is that in order to


get a medium to those temperatures you have to completely isolate it from anything to do with terrestrial environment it can have no contact like with anything on Earth basically so this means what we this is the technology that I just described is it fundamentally what it does is it takes this Fuel and uh it isolates it from any terrestrial condition so that it has no idea it's on Earth it's not touching any object that that's at room temperature including the walls of the containment even including the walls of the containment building or containment device or even air or anything like this so so it's that part


um that makes it safe in this and there's there's actually another aspect to it but that that fundamental part makes it so safe um in in the main lines approach diffusion is also that it's very hot but there's very very few particles in at any time in in the thing that we view the power plant and the actually the more correct way to do it is you say there's very few particles per unit volume so in a cubic centimeter and cubic meter or something so we can do this so right now we're although we don't think of air really as there's atoms floating around us and there's a


density because if I wave my hand I can feel the air pushing against my face that means we're in a fluid or a gas which is around us that has a particular number of atoms per cubic meter right so it's about this actually turns out to be 10 to the 25th so this is one with 25 zeros behind it per cubic meter so we can figure out like cubic like cubic meters about like this yeah the volume of this table like the whole volume um okay very good so like Fusion there's a few of those so Fusion like the mainstream one of fusion like what we're working on at MIT will have a hundred thousand times less particles per unit volume than that so this is


very interesting because it's extraordinarily Hot 100 million degrees but it's very tenuous and what matters from the engineering and safety point of view is the amount of energy which is stored per unit volume because this tells you about the the scenarios and that's what you worry about because when those kinds of energies are released Suddenly It's like what would be the consequences right so the consequences of this are essentially zero because that's less energy content than boiling water because of the low density because of the low density so if you take water is at about 100 million to a billion times


more dense than this so even though it's at much lower temperature it's actually still it has more energy content so if for this reason um you know one of the ways that I explain this is that if you imagine a power plant that's like powering Cambridge Massachusetts like if you were to which you you wouldn't do this directly but if you went like this on it it actually extinguishes the fusion because it gets too cold immediately yeah so that's the other one and the other part is that it does not and because it works by staying hot rather than a chain reaction it can't run out of control that's the other part of it


so by the way this is what very much distinguishes it from fission it's not a process that can run away from you because it's it's basically thermally stable what does thermostable mean that means is that you want to run it at the optimization in temperature such that if it deviates away from that temperature the reactivity gets lower and and the reason for this is because it's hard to keep the reactivity going like it's a very hard fire to keep going basically also it doesn't it doesn't run away from you it can't run away how difficult is the control there to keep it at that it varies from from concept to concept but


in generally it's fairly it's fairly easy to do that and the easiest thing it can't it can't physically run away from you because the other part of it is that there's just at any given time there's a very very small amount of fuel available to fuse anyway so this means that that's always intrinsically limited to this so if it even if the power consumption of the device goes up it just kind of burns itself out immediately yeah so you are the just to take a tan another tangent on tangent you're the director of mit's plasma science at Fusion Center uh we'll talk about maybe you can mention some interesting aspects of the history of the center in the broader history


of uh MIT maybe brought a history of Science and Engineering in the history of human civilization but also just the link on the safety aspect you know um how do you prevent you know some of the amazing reactors that you're designing how do you prevent from destroying all of human civilization in the process what's the safety protocols Fusion is um interesting because it's not really directly weaponizable because what I mean by that is that you have you have to work very hard to make these conditions and which you can get energy gain from from fusion um and uh this means that the the when


we design these devices with respect to application in the energy field is that they you know you the while while they will because they're producing large amounts of power and they will have hot things inside of them this means that they have like a level of industrial Hazard which is very similar to like you would have like in a chemical processing plant or anything like that any kind of energy plant actually has these as well too but the underlying under underneath the core technology like can't be directly used uh in in a nefarious way because of the power that's being emitted it just basically will if you try to do those


things typically it just stops working so the safety concerns have to do with just regular things that uh like equipment malfunctioning uh melting of equip like all this kind of stuff that yeah it has nothing to do with Fusion necessarily yeah I mean usually what we worry about is the viability because in the end we build pretty complex objects to realize these requirements and so what we try really hard to do is like not damage those components which but those are things which are internal to the to the fusion device and and it's this is not something that you would um consider about like it would as you


say destroy human civilization because that release of energy is just inherently limited because of the fusion process so it doesn't say that there's zero so you asked about the other feature for that it's safe so it is the process process itself is intrinsically safe but because it's a complex technology you still have to take into account consideration aspects of the safety so it produces ionizing radiation instantaneously so you have to take care of this which means that you Shield it you think of like your dental X-rays or or treatments for cancer and things like this we we always Shield ourselves from this so we get the beneficial effects


but we minimize the harmful effects of those so there are those aspects of it as well too yeah so we'll return to mit's plasma science the future Center but let us Linger on the uh destruction of human civilization uh which brings us to the topic of nuclear fission what is that so the the process that is inside nuclear weapons and current nuclear power plants so it relies on the same underlying physical principle but it's exactly the opposite a few which actually the names imply Fusion means bringing things together fission means splitting things apart so fission requires the heaviest instead of the lightest and the most unstable versus


the most stable uh elements so this tends to be uranium or plutonium primarily uranium so take uranium so uranium-235 is one of the that this is one of the heaviest unstable elements and what happens is that this is a fission is triggered by the fact that one of these subatomic particles the neutron which has no electric charge basically gets in proximity enough to this and and triggers an instability effectively inside of this what is teetering on the border of instability and basically splits it apart and that's the fission right the fissioning um and so when that happens because the


products that are and kind of roughly splits in two but it's not even that it's actually more complicated splits into this whole array of lighter elements and nuclei and when that happens there's less rest Mass uh uh laugh than the original one so it's actually the same so it's again it's rearrangement of the strong nuclear force that's happening um but that's the source of the energy and so in the end it's like so this is a famous graph that we show everybody is is basically it turns out every element that exists in the periodic table all the things that make up everything have uh have a remember you asked a good


question it was like so should we think of mass as being the same as stored energy yes so you can make a plot that basically shows the relative amount of stored energy in all of the elements that are stable and make up basically the world okay in the universe and it turns out that this one has a maximum amount of of stability or storage at iron so it's kind of in the middle of the periodic table because this goes from you know it's roughly that and so this what that means is that if um if you take something heavier than iron like uranium which is which is more than twice as heavy than that and you


split apart if you somehow just magically you just split apart as constituents and you get something that's latter that will because it moves to a more stable energy state it releases kinetic energy that's the energy that we use kinetic energy meaning the movement of things so it's actually an energy you can do something with and fusion sits on the other side of that because it's also moving towards iron but it's do it has to do it through Fusion together so this leads to some pretty profound differences as I said they have some underlying physics or science um uh proximity to each other but


they're literally the opposite so Fusion why is this it actually goes into practical implications of it which is that fission can happen at room temperature it's because there's this neutron has no electric charge and therefore it's literally room temperature neutrons that actually trigger the reaction so this means um in order to establish uh what's going on with it and it works by a chain reaction is that you can do this at room temperature so Enrico Fermi did this like on a on a University campus University of Chicago campus the first sustained you know chain reaction was


done underneath the squash court with a big blocks of graphite you know it was still don't get me wrong an incredible human achievement right but that's you know and then you think about Fusion I have to build a Contraption of some kind that's going to get to 100 million degrees okay wow that's a big difference the other one is about the chain reaction that namely fission works by the fact that when that fission occurs it actually produces free neutrons free neutrons particularly if they get slowed down to room temperature trigger can trigger other fission reactions if there's other uranium nearby or physometers so this means that


the way that it releases energy is that you set this up in a very careful way such that every on average every reaction that happens exactly releases enough neutrons and slows down that they actually make another reaction one exactly one and what this means is that because each reaction releases a fixed amount of energy you do this and then in time this looks like just a constant power output so that's how our fission power plant works and so either the control of the the chain reactions is extremely difficult and extremely important for it's very important and when you intentionally design it that it creates more than one fission reaction


per per starting reaction that it exponentiates away but which is which is what a nuclear weapon is yeah so how does an atomic weapon work how does a hydrogen bomb work asking for a friend yeah yeah so um at its heart what it how what you do is you very quickly put together enough of these materials that can undergo fission with room temperature neutrons and you put them together fast enough that what happens is that this process can essentially grow mathematically like very fast and so this releases large amounts of energy so that's the underlying reason that it works


so you've heard of a fusion weapon so this is interesting is that it is it but it's dislike Fusion Energy in the sense that what happens is that you're using Fusion reactions to but it's simply it increases the gain actually of the weapon rather than um it's it's not a pure at its heart it's still a fission weapon you're just using Fusion reactions as a sort of intermediate Catalyst basically to get even more energy out of it but it's not directly applicable to to be used in an energy source does it terrify you just again to step back at the philosophical that humans have been able to use physics and


uh engineering to create such powerful weapons I wouldn't say terrify I mean we should be this is the this is the progress of human every time that we've gone access you talk again you know the day the universe changed those really changed when we got access to new kinds of energy sources but every time you get acts and typically what this meant was you get access to more intense energy right that's and that's what that was and so the ability to move from burning wood to using coal to using gasoline and petrol and then finally to use this is that


is that both the potency and the consequences are elevated around those things it's just like you said the the way that Fusion nuclear fusion would change the world I don't think unless we think really deeply we'll be able to anticipate some of the things we can create there's going to be a lot of amazing stuff but then that amazing stuff is going to enable more amazing stuff and more unfortunately or uh depending how you see on it more powerful weapons well yeah but see that's the thing Fusion breaks that Trend in the following way so one of them so Fusion doesn't work on


a chain reaction there's no Chain Reaction zero so this means it cannot physically exponentiate away on you because it works and actually this is why Star by the way we know this already it's why stars are so stable why most stars and suns are so stable it's because they are regulated through their own temperature and their Heating because what's happening is not that there's some probability of this exponentiating away is that the energy that's being released by Fusion basically is keeping the fire hot and these tend to be you know and when it comes down to thermodynamics and


things like this there's a reason for example it's pretty easy to keep of constant temperature like in an oven and things like this it's the same thing infusion so this is actually one of the features that I would argue Fusion breaks the breaks the trend of this is that it's it has more energy intensity than than fission on on paper but it actually does not have the consequences of control and sort of Rapid Release of the energy because it's actually it the physical system just doesn't want to do that yeah we're gonna have to look elsewhere for the weapons with which we fight World War III fair enough uh so


what is plasma that you may may have not mentioned you mentioned ions and electrons so what is plasma what is the role of plasma and nuclear fusion so plasma is a phase of matter or state of matter so unfortunately our schools don't it's like I'm not sure why this is the case but all all children learn the three phases of matter right so and what does this mean so we'll take like Waters an example so if you if it's cold it's ice it's in a solid phase right and then if you heat it up the temp it's the temperature that typically depends sets the phase although it's not it's not only temperature so you heat it up and


you go to a liquid and obviously it changes its physical properties because it can you can pour it and so forth right and then if you heat this up enough it turns into a gas and a gas behaves differently because there's a very Sudden Change in the density actually that's what's happening so it changes by about a factor of ten thousand in density from the from the liquid phase into when you make it into steam atmospheric pressure all very good except the problem is they forgot like what happens if you just keep elevating the temperature you don't want to give kids ideas they're going to start experimenting they're going to start


heating up the gas it's good to start doing anyway so you um it turns out that once you get above it's approximately five or ten thousand degrees Celsius then you hit a new phase of matter and actually that's the phase of matter that is for all pretty much all the temperatures that are above that as well too um and so what does that mean so it actually changes phase so it's a different state of matter and the reason that it becomes a different state of matter is that it's hot enough that what happens is that the atoms that make up remember go back to Feynman right everything's made up of these individual


things these atoms but atoms can actually themselves be um which are which are made of nuclei which contain the positive particles and the neutrons and then the electrons which are very very light very much less mass than than the nucleus and that surround this this is what makes up an atom so a plasma is what happens when you start pulling away enough of those electrons that they're free from the ion so almost all the atoms that make up us up and this water and all that the electrons are in tightly bound States and basically they're extremely stable once you're about five thousand or ten thousand degrees you start pulling off


the electrons and what this means is that now the medium that is there its constituent particles have mostly have net charge on them so why does that matter it's because now this means that the particles can interact but through their electric charge in some sense they were when it was in the atom as well too but now that they're free particles this means that they start it fundamentally changes the behavior it doesn't behave like a gas it doesn't behave like a solid or a liquid I mean he's like a plasma right and so why is this why is it disappointing that we don't speak about this it's because 99 of the universe is in the plasma


State it's called Stars and in fact our own Sun at the center of the sun is what clearly a plasma but actually the surface of the sun which is around 5500 Celsius is also a plasma because it's hot enough that is that in fact the things that you see sometimes you see these pictures from the surface of the Sun amazing like Satellite photographs of like those big arms of things and of light coming off of the surface of the Sun and solar flares those are plasmas what are some interesting ways that this forced state of matter is different than gas let's go to how a gas works right so the reason a gap and it goes back to


fireman's Brilliance and saying that this is the most important concept the reason actually solid liquid and gas phases work is because the the nature of the interaction between the atoms changes and so in a gas you can think of this as being this room and the things although you can't see them is that the molecules are flying around but then with some frequency they basically bounce into each other and when they bounce into each other the exchange momentum and energy around on this and so it turns out that the probability and the distances and the scattering of those of what they do it's it's those interactions that set the uh about how a


gas behaves so what do you mean by this well so for example if I take a a an imaginary test particle of some kind like I spray something into the air that's got a particular color in fact you can do it in liquids as well too like how it gradually will disperse away from you this is this is fundamentally set because of the way that those particles are bouncing into the probabilities of those uh the rate that they go at and the distance that they go out and so forth so this was figured out by Einstein and others at the beginning of the Browning motion all these kinds of things these are these were set um up at the beginning of the last century and


it was really like this great Revelation wow this is why matter behaves the way that it does like wow um um so but it's really like and also in liquids and in solids like what really matters is is is is is how you're interacting with your nearest neighbor so you think about that one the gas particles are basically going around until the until they actually hit into each other though they don't really exchange information and it's the same in a liquid you're kind of beside each other but you can kind of move around in a solid you're literally like stuck beside your neighbor you can't move like


yeah plasmas are are weird in the sense is that they're it's not like that so and it's because the particles have electric charge this means that they can push against each other without actually being in close proximity to each other it's not that's not an infinitely true statement which we go together it's a little bit more technical but basically this means that you can start having action or exchange of information at a distance and that's in fact the definition of a plasma that it says these have a technical name is called a coulomb collision it just means that it's


dictated by this Force which is being pushed between the charged particles is that the definition of a plasma is a is a medium in which the collective behavior is dominated by these collisions at a distance so you can imagine then this starts to to give you some Strange Behaviors um uh which I could I could quickly talk about like for example one of the most counterintuitive ones is as plasmas get more hot as they get higher in temperature then the collisions happen less frequently it's like like what that doesn't make any sense when particles go faster you think they would Collide more often


but because the particles are interacting through interacting through their electric field when they're going faster they actually spend less time in the influential field of each other and so they talk to each other Less in an energy and momentum exchange point of view it's just one of the count one of the counter-intuitive aspects of plasmas which is probably very uh relevant for nuclear fusion yes exactly so if I can try to summarize what a nuclear fusion reactor is supposed to do so you have what a couple of elements what are usually the elements usually deuterium and tritium which are the


heavy forms of hydrogen hydrogen you have those and you start heating it and then as you start heating it I forgot the temperature you said about 100 million no first first it becomes oh first it becomes a plastic so it's a gas and then it turns into a plasma at about 10 000 degrees and then so you have a bunch of electrons and ions flying around and then you keep heating the thing and uh I guess as you heat the thing the ions hit each other rarer and rarer Yes except oh man that's not fun so you have to keep heating it um such that uh you have to keep hitting into the probability of them colliding


becomes reasonably high and so and also on top of that I'm sorry to interrupt you have to prevent them from hitting the walls of the reactor that's exactly somehow so you asked about the the definitions of the requirements for Fusion so the most famous one or some sense the most intuitive one is the temperature and the reason for that is that you you can make many many kinds of plasmas that have zero Fusion going on in them and the reason for this is that the average so I mean you can make a plasma at around 10 000 in fact if you come by the way you're welcome to come to our laboratory at the psfc I can show you a demonstration of a plasma that you


can see with your eyes instead of about 10 000 degrees and you can put your hand up beside it and all this and it's like and nothing there's zero Fusion going on so you have uh so what was the temperature of the plasma about ten thousand degrees you can stick your hand in well you can't stick your hand into it but there's a glass tube you can basically see this yeah yeah and you can put your hand on the glass too because it's what's the colors of purple it's yeah it's purple yeah it is it is kind of beautiful um yeah plasmas are actually quite uh astonishing sometimes in their beauty actually one of the most amazing forms


of plasma is Lightning by the way which is is instantaneous form of plasma that exists on Earth but immediately goes away because everything else around it it's at room temperature yeah so there's different requirements in this so making a plasma takes about this but at 10 000 degrees even at a million degrees there's almost no probability of the fusion reactions occurring and this is because while the the charged particles can hit into each other if you go back to the very beginning of this remember I said oh these charged particles have to get to within distances which are like this size of a nucleus because of the strong


nuclear force well unfortunately as the particles get closer this the repulsion that comes from the charge the coulomb force increases like the inverse distance squared I don't know so as they get closer they're pushing harder and harder apart so then then it gets a little bit more exotic which you maybe you'll like though that it turns out that you people understood this and um at the beginning of the uh of of the age of after Rutherford discovered the nucleus it's like oh yeah I was like how are we going to how's this going to work right because how do you get anything within


these distances it's a good inquire extraordinary energy and it does and in fact when you look at those energies they're very very high um but it turns out quantum physics comes to the rescue because the particles aren't aren't actually just particles they're also waves this is the point of quantum right the you can treat them both as waves and as as particles and it turns out if you get if they get in close enough proximity to each other then the particle pops through basically this energy barrier through an effect called Quantum tunneling which is really just the transposition of the fact that it's


a wave so that it has a finite probability of this it's it's this by the way you talk about like do you have a hard time like conceptualizing this these are this is one of them yeah this is like throwing a ping-pong ball like at a a piece of paper and then every like you know 100 of them just like magically show up on the other side of the paper without seemingly breaking the paper I mean to use a physical analogy yeah that's phenomena is important is uh critical for the function of nuclear fusion yeah all kinds of fusions so this this is the reason why Stars can work as well too like the stars would have to be much much hotter actually to be able to


in fact it's not clear that they would actually ignite in fact without this effect and so we get to that so this is why there's another requirement it's it's not so you must make a plasma but you also also must get it very hot in order for the reactions to have a significant probability to actually fuse and it actually falls effectively almost to zero for lower temperatures as well too so there's some nice equation yes that gets you to 50 million degrees or like uh yeah the or that you said practically speaking 100 million so it's a really simple equation it's the ideal gas law basically almost so it's in the end you've got a certain number of


particle of these Fusion particles in the plasma state they're in the plasma State there's a certain number of particles and if the confinement is perfect if you put in a certain content of energy then basically eventually they just they come up in a temperature and they become they they go up they go up to high temperature this turns out to be by the way extraordinarily small amounts of energy and you go what it's like I'm getting something to like 100 million degrees that's gonna take the biggest flame burner that I've ever seen no and the reason for this is it goes back to the energy content of of this so yeah


you have to there's you have to get it to high average energy but there's very very few particles this is low density low density in the reactor is this so you the way that you do this is primarily again this is not exactly true in all kinds of fusion but in the in the primary one that we work on a magnetic Fusion this is all happening in a hard vacuum so it's like it's happening in outer space so basically you've gotten rid of all the other particles except for these specialized one at a time uh no actually it's even easier than that you you connect a gas valve and you basically leak gas into it in a controlled fashion yeah yeah well this


is beautiful the gas cylinder how do you get it from hitting the walls yeah so now you've touched on the other necessary requirements so it turns out it's not just temperature that's required you must also confine it so what does this mean confine it and there's two types of confinement as you mentioned you mentioned the magnetic one magnetic one and there's another one called inertial as well too but the general principle actually has nothing to do with in particular with what your what with the technology is that you use to confine it it's because this goes back to the fact that the requirement in this is high temperature


and thermal content so it's like Building A Fire Man and what this means is that if you when you release the energy into this or or apply heat to this if it just instantly leaks out it can never get hot right so you're familiar with this it's like you've got something that you're you're trying to apply heat to but you're just throwing the heat away very quickly this is why we insulate homes by the way and things like those right it's like you don't want the heat that's coming into this room to just immediately leave because you'll just start consuming infinite amounts of heat to try to keep it hot so in the end this is one of the


requirements and it actually has a name we call the energy confinement time so this means if you release a certain amount of energy into this fuel um kind of how long you sit there and you look at your watch how long does it take for this energy to like leave the system so you could imagine that in this room that you know these heaters are putting energy into the air in this room and you waited for a day a but all the Heat have gone to outside if I open up the windows oh there that's energy confinement time okay so it's the same concept as that so this is an important one so all Fusion must have confinement uh there's another more esoteric reason


for this which is that people often confuse temperature and energy so what I mean by that so this is literally a temperature which means that it is a system in which all the particles every particle has high kinetic energy and is actually in a fully relaxed State namely that entropy has been maximized and it gets a little bit more technical but this means that basically it is it is a thermal system so it's like the air in this room it's like the water it's the water in this these all have temperatures which means that there's a distribution of those energies because the particles have collided so much that it's there so we


this is distinguished from having high energy particles like what we have in like particle accelerators like CERN and so forth those are high kinetic energy but it's not a temperature so it actually doesn't count as confinement so we go through all of those you have temperature um and then the other requirement not too surprising is actually that there has to be enough density of the fuel enough but enough but not too much yes and so in the end um the way that it there's a fancy name for it it's called The Lawson Criterion because it was it was it was formulated by scientists in the United Kingdom


about 1956 or 1957 and this was essentially the realization of oh this is what it's going to take regardless of the confinement method these are this is the basic what it is actually Power Balance it just says oh there's a certain amount of heat coming in which is coming from the fusion reaction itself because the fusion reaction heats the fuel versus how fast you would lose it and it basically summarizes summarized by those three parameters which are fairly simple so temperature and then the reason we say 100 million degrees is because almost always in in for for this kind of fusion deuterium tritium Fusion the minimum in the


density and the confinement time product is at about 100 million so you almost always design your device around that minimum and then you try to get it contained well enough and you try to get enough density so you know so that temperature thing sounds crazy right that's what we've actually achieved in the laboratory like our experiment here at MIT when it ran it's Optimum configuration it was at 100 million degrees but it wasn't actually the the product of the density in the confinement time wasn't sufficient that we were at a place that we were getting high net energy gain but it was making Fusion


reactions so this is the sequence that you go through make a plasma then you get it hot enough and when you get it hot enough the fusion reactions start happening so rapidly that it's overcoming the the rate at which it's leaking heat to the outside world and at some point it just becomes like a star like a sun and our own our own son and a star doesn't have anything plugged into it it's just keeping itself hot through its own Fusion reactions in the end that's really close to what a fusion power plant would look like what does it visually look like does it does it look like like you said like purple plasma you know yeah actually it's it's


invisible to the eye because it's so hot that it's basically emitting light in frequencies that we can't detect it's literally it's invisible in fact light goes through it visible light goes through it so easy that if you were to look at it what you would see in in our own particular configuration what we make is in the end is a donut shaped um it's a vacuum vessel to keep the air out of it and when you in when you turn on the plasma it gets so hot that most of it just disappears in the visible spectrum you can't see anything and there's very very cold plasma which is between 10 and 100 000 degrees which


is out in the very periphery of it which is kind of so the very cold plasma is allowed to interact with the kind of has to interact with something eventually at the boundary of the vacuum vessel and this kind of makes a little halo around it and it glows this beautiful purple light basically and these are that's the um that's the that's what we can sense in the human Spectrum yeah I I remember reading on uh subreddit called shower thoughts uh which people should check out it's just fascinating philosophical ideas that strike you while you're in the shower and one of them was it's lucky that a fire when it burns communicates


that it's hot using visible light otherwise humans would be screwed um I don't know if there's a deep profound truth to that but nevertheless I did find it on shower thought subreddit actually I do have there this goes off in a bit of it you're right this is actually it's interesting because you know as a scientist you also think about evolutionary functions and how we got like why do we have the senses that we do yes interesting question right like why can bees see an UltraViolet and we can't then you go well it's natural selection for some reason this wasn't really particularly important to us right why can't we see


in the infrared and other things can it's like um because the people that could it's a fascinating question right obviously there's some there's some advantage that you have there that isn't there and even color distinguishing right of something safe to ease not say whatever it would be uh I actually go back to this because it's something like that I tell all of my my students when I'm teaching um ionizing radiation and radiological safety whatever you say there's a cultural concern or that when people hear the word radiation like what does this mean it literally just means light is what it means right but it's light in


different parts of the spectrum right and so it turns out besides the visible light that we can see here we are immersed in almost the totality of the electromagnetic spectrum there is visible light there's infrared light there is microwaves going around as that's how our cell phone works you can't it's way past our detection capability but also higher energy ones which have to do with ultraviolet light how you get a sunburn um and even X-rays and things like this at small levels are continually being like from the concrete in this in the walls of this hotel there's x-rays hitting our body continuously I can


bring out we can go down to the lab at MIT can bring out a detector and show you every single room will have and have these by our body you mean the 10 to the 28 atoms yeah the 10 to the 28 atoms and they're coming in and they're interacting with those things and those particularly the ones where the light is at higher average energy per per light particle those are the ones that can possibly have an effect on human health so we we have it's interesting humans and all animals of evolved on Earth where we're immersed in that all the time yeah there's natural sources of radiation all the time yet we have zero ability to detect it like zero


yeah and our ability cognitive ability to filter it all out and not it would not really overwhelm us actually if we could see all of it but my main point is it goes back to your thing about fire and self-protection if if these ionize if ionizing radiation was such a critical aspect of the health of organisms on Earth we would almost certainly have evolved methods to detect it and we have none and uh yes the physical world that's all around us yeah you're blowing my mind uh Dr Dennis white okay let's so you have experience with Magnetic confinement you have experience with inertial confinement most of your work has been a


magnetic economy but let's sort of um talk about the the the the sexy recent thing for for a bit of a time there's been a breakthrough in the news uh uh that uh laser-based inertial confinement was used by Doe's National ignition facility at the Lawrence Livermore National Laboratory can you explain this breakthrough that happened in December yeah so it goes to the set of criteria that I talked about before about getting high energy gain so in the end what what are we after in Fusion is that we we basically assemble this plasma fuel in some way and we provided a


starting amount of energy think of lighting the fire and what you want to do is get back like significant excess gain from the fact that the fusion is is making more is releasing the energy so it's it's like the equivalent of like we want to have a match a small match light a fire and then the fire Keeps Us hot it's like this is very much like that so as I said we've we've made many of the and what I mean by we it's like the fusion Community has pursued aspects of this through a variety of different confinement uh methodologies um is that the um the key part about what happens what was the threshold we had never


gotten over before was that if you only consider the plasma fuel not the not the total engineering system but just the plasma fuel itself we had not gotten to the point yet where basically the size of the match was was smaller than the amount of energy that we got from the fusion is there a good term for when the output is greater than the input yes yes it there is well there's several special definitions of this so one of them is that if you if you like in a fire if you light a match and you have it there and it's an infinitesimal amount of energy compared to what you're getting out of the fire we call this ignition which makes sense right this is like what the


what our own sign is as well too so that that was not ignition in that sense as well too so what we call this the scientific what the one that we I just talked about which is for for some instance when I get enough Fusion energy released compared to the size of the match we call this sign to Civic break even break even break even and it's because you've gotten past the fact that this is Unity now at this point what is a fusion gain or as using the notation Q from the paper overview of the spark Tacoma before talk using just the same kind of terms yeah actually so the technical term is Q capital Q people actually use Cube we actually use


capital Q or sometimes it's called Q is taken Q sub P or something like this okay okay so this is which which means what what it means is that it's in the plasma so all we're considering is is the energy balance or a gain that comes from the plasma itself we're not considering the Technologies which are around it which are providing the containment and so forth so why why the excitement and so well because for one reason it's a rather Sim it's a rather simple threshold to get over to understand that you're getting more energy out from the fusion even the theoretical sense than you were from the you know from the starting match do you


mean consent actually simple it's conceptually simple that you get past one that everyone under like when you're less than one that's much less interesting than getting past one because that's a really big you started to get fast but it's it's really it really is a scientific threshold because what QP actually um denotes is the relative amount of self-heating that's happening in the in the plasma so what I mean by this is that in the end in these systems for and what what you want is something that where the the relative amount of of heating which is keeping the fuel hot is dominated by from the fusion reactions


themselves and and so it becomes it's it's sort of like thinking like a bonfire is a lot more interesting physically than just holding a blow torch to a wet log right there's a lot more Dynamics it's a lot more self-evolved and so forth and what we're excited as a scientists is that it's clear that the the in that experiment that they actually got to a point where the fusion reactions themselves were actually altering the state of the plasma I was like wow I mean we'd seen it in glimpses before in magnetic confinement at relatively small levels but apparently it seems like in this


experiment it's likely to be a dominant dominated by self-heating that's a very important that's a very interesting that makes it a self-sustaining type of it's more self-sustaining it's more self-referential system uh in in a sense and it sort of self-evolves in a way again it's not that it's going to evolve to a dangerous State it's just that we want to see what happens when when the fusion is the dominant heating source and we'll talk about that but so there's also another element which is the inertial confinement uh laser-based initial confinement is kind of a little bit of another dog okay so a lot of the broad nuclear fusion


Community has been focused on magnetic confinement can you explain just how laser-based inertial confinement works so it says uh 192 laser beams were aligned on a deuterium tritium DT Target smaller than a p yes uh this is like actually yeah okay well you know it depends not all P's are made the same but uh this is like throwing a perfect strike in baseball from a pitch this is like a journalist wrote this I think this is like oh no it's not a journalist it's do yeah yeah we try to use all these analogies this is like throwing a perfect strike in baseball from a pitcher's Mount 350 miles away from the plate there you go Department of energy


the United States Department of energy wrote this okay so can you explain interesting what the what the lasers what what actually happens yeah actually there's usually Mass confusion about this so um so what's going on in this form over so the fuel is is is delivered in a discrete the Fusion fuel the deuterium and tritium is in a discrete spherical it's more like a BB let's call it a BB so it's a small one and all the fuel that you're going to try to to burn is basically there okay and it's about that size so what's hap so how are you going to get and it's that literally it's like at 20 degrees


above absolute zero because the deuterium and tritium are kept in in a liquid in a solid state so the fuel is injected not as a gas as a solid it's actually and it's very and these are particular experiments they can introduce one of these you know these targets once per day approximately something like that because it's very it's very it's kind of amazing technology actually that I know some of the people that worked on this uh back in the is um they actually make these things out of BB size of this frozen fuel it's actually a cryogenic temperatures and they're almost like Smooth to the atom


level I mean they're amazing pieces of Technology so what you do in the end is think what you have is a spherical assembly of this fuel like a ball and what what is the purpose of the lasers the purpose of the lasers is to provide Optical energy to the very outside of this and what happens is the that energy is absorbed because it's it's in the solid phase of matter so it's absorbed really in the surface and then what happens is that when it's absorbed in something called the ablator what does that mean it means it goes instantly from the solid phase to the gas phase so it becomes like a rocket engine and but


you hit it like very uniformly so all there's like rocket engines coming off this surface think of like an asteroid almost where there's like rockets coming off and all this thing so what does that do what does a rocket do it actually pushes by Newton's Laws right it pushes the other thing on the other side of it equal and opposite reaction it pushes it in so what it does is it that the lasers actually don't Heat this is what was confusing people think the laser oh we're gonna get it to 100 million degrees in fact you want the exact opposite of this what you want to do is get essentially a rocket going out like this and then what happens is that the


sphere like and this is happening in a billionth of a second or less actually this rapidly that that Force like so rapidly compresses the fuel that what happens is that you're squeezing down on it and and and you know it's like what was the CBB that's bad actually B I should have started with a basketball basket goes from like a basketball down to something like like this and then billionth of a second and when that when that happens I mean you scale that in your mind so when that happens and in this this comes from almost from classical physics so there's some Quantum in it as well too but basically if you can do this


um like very uniformly and so-called adiabatically like you're not actually heating the fuel what happens is you get adiabatic compression such that the very center of this thing all of a sudden just spikes up in temperature because it's it's it's actually done so fast so why is it called inertial Fusion it's because you're doing this on such fast time scales that the inertia of the hot fuel basically is still finite so it can't like push itself apart before the fusion happens oh wow so how do you make it so how do you make it so fast this is why you use lasers because you're applying this energy in very very short periods of


time like under a fraction of a billionth of a second and so basically that and then the force which is coming from this comes from the energy of the lasers which which is basically the rocket action which does the compression which is the force is the inward facing Force is is that is that increasing the temperature no exponential you want to keep the fuel cold and then and just literally just ideally compress it and then in something which is at the very center of that compressed sphere because you've compressed it so rapidly the laws of physics basically require for it to increase in temperature so the the effect is like if


you know the thing so adiabatic cooling were actually fairly familiar with if you take a spray can right and you push the button when it when it rapidly expands it cools this is the nature of a lot of cooling technology we use actually well the opposite is true that if you would take all of those particles and jam them together very fast back in they want to heat up and that's what happens and then what happens is you you basically have this very cold compressed set of Fusion fuel and at the center of this it goes to this 100 million degrees Celsius and so if it gets to that 100 million degrees Celsius the Fusion fuel starts to burn


and when that Fusion fuel starts to burn it wants to heat up the other cold fuel around it and it just basically propagates out so fast that what you would do ideally you would actually burn in a fusion sense most of the fuel that's in the pellet so this was very exciting because what they had done was they it's clear that they propagated this they got this what they call a hot spot and in fact that this heating can propagate it out into the fuel um and that's that's the science behind inertial Fusion so the idea behind a reactor is based on this kind of inertial uh uh confinement is that you would what have a new BB every like 10


times a second or something like and then there's some kind of yeah so there's a incredible device that you kind of implied that kind of has to create one of those BBS that did so you have to make the BBS very fast there's reports on this but about what what does it mean you know the starting point is can you make this game so this was a scientific achievement primarily because and the rest is just engineering no no no the rest is incredibly complicated engineering well in fact there's still physics hurdles to overcome so so where does this come from and it's actually because if you want to make an energy source out of this


um this had a gain of around 1.5 that namely the Fusion Energy was approximately was 1.5 times the the laser input energy okay this is a fairly significant threshold however from the from the science of what I just told you is that there's two fundamental efficiencies which come into it which really come from physics really one of them is hydrodynamic efficiency what I mean by this is that it's a rocket so this just has a fundamental uh efficiency built into it which comes out to orders of like 10 percent so this means is that your your ability to do work on the system is just limited by that okay and then the other one is the


efficiency of laser systems themselves which if they're wall plug efficiency is 10 you've done spectacularly well in fact the wall plug efficiency of the ones using experiments are like more like one percent right so when you go through all of this the approximate you know place that you're ordering this is for for fusion power plant would be a gain of a hundred not 1.5 so you still you know and hopefully we see experiments that keep climbing up towards higher and higher gain but then the whole fusion power plant is a totally different thing so it's not one it's not one BB and one laser pulse per day it's like ten times five or ten


times per second like that right so you're doing it there and then then and then comes the other aspects so it's making the targets delivering them being able to repeatedly get them to burn and then we haven't even talked about like how do you then get the Fusion Energy out which is mainly because these things are basically micro you know implosions which are occurring so this energy is coming out to some medium on the outside that you've got to figure out how to extract the energy out of this thing how do you convert that energy to electricity so in the end you have to basically convert it into heat in some


way so most of the pro what you in the end what Fusion makes mostly is like very energetic particles from the fusion reaction so you have to slow those down in some way and then make heat out of it so basically the conversion of the kinetic energy of the particles into heating some engineered material that's on the outside of this and that's from a physics perspective is a somewhat solved problem but from an engineering is is still it's still yeah physics I can draw the I can show you all the equations that tell you about how it slows down and converts kinetic energy into heat and then what that heat means you know you can write out like an ideal thermal


cycle like a carnosis so the physics of that yeah great the integrated engineering of this is a whole other thing a last case of maybe talk about the difference between a natural magnetic uh but first we'll talk about magnetic but let me just Linger on this breakthrough you know it's nice to have exciting things but in a deep human sense there's no competition in science and engineering well like you said we were broad first of all we are a Humanity all together and you talk about this it's a bunch of countries collaborating it's it's really exciting uh there's a nuclear fusion Community broadly but then there's also


MIT there's colors and logos and it's exciting and there's a that you uh you have uh friends and colleagues here that that work extremely hard and done some incredible stuff is there some sort of how do you feel seeing somebody else uh get a breakthrough and uh using a different technology is that exciting uh is this does the competitive fire uh get uh all of the above I mean I mean the ignition you know I have so uh you know to you know just to wave the wave the flag a little bit so MIT was a central player in in this in this accomplishment um interesting I would say it showed our two some of our two best traits so one of them was that the


like how do you know that this happened this measurement right so one of the ways to do this is if I told you is that the in the DT Fusion what it actually the product that comes out is helium I would call an alpha but it's helium um and a free Neutron right so the neutron contains 80 percent of the fusion of the energy released by the fusion reaction and it also because it has lack it lacks a charge it basically tends to just escape and go flying out so this is what we would use eventually for that's mostly what Fusion Energy would be but so what um my my colleagues my scientific colleagues at uh at the plaza


science Infusion Center built were extraordinary measurement tools of being able to see the exact details of not only the number of neutrons that were coming out but actually what energy that they're at and by looking at that that configuration it reveals enormous I'm not gonna I'm not gonna scoop them because they need to publish the paper but it it reveals enormous amounts of scientific information about what's happening in that process that I just described so exciting I mean and I there you know I have colleagues there that have worked like for 30 years on this for that moment of course you're excited for them I mean and there's one of those


like there's there's nothing it's hard to describe to people who aren't they haven't it's like almost addicting to be a scientist when you get to be at the Forefront of research of anything like when you see like an actual discovery of some kind and you're looking at it particularly when you're are the person who did it right and you go no human being has ever seen this or understood this it's like it's pretty thrilling right so even even in proxy it's it's incredibly thrilling to see this it's not I don't know it's rivalry or jealousy it's like I can tell you already Fusion is really hard so anything that keeps pushing the needle


forward is a good thing but we also have to be realistic about what it means you know to making a Fusion Energy System that's that's and then but that's the fun I mean these are the are still the early steps you maybe you can say the early leaps uh so let's talk about the magnetic confinement uh what is how does uh magnetic confinement work what's the takamak uh yeah how does it all work so go back to that so why inertial confinement works on the same principle that a star works so like what is the confinement mechanism in the star is gravity because it's it's it's it's its own


inertia of the something the size of the sun basically pushes a literally a force by gravity against the center so the center is is very very hot 20 million degrees and literally outside the sun it's essentially zero because it's vacuum of space how the hell does that do that it does that by and is out of through like why doesn't just leak all of its heat it doesn't leak its heat because it all held together by the fact that it can't escape because of its own gravity so this is why the fusion happens in the center of the Tsar like we think of the surface of the Sun as being hot that's the coldest part of the star so if our own sudden this is about


in 5500 degrees a beautiful Symmetry by the way it's like so how do we know all this because we can't of course see directly into the interior of the Sun by knowing the volume and the temperature of the surface of the Sun you know exactly how much power it's putting out and by this you you know that this is coming from Fusion reactions occurring at exactly the same rate in the middle of the Sun is it possible as a small tangent to build uh an inertial confinement system like the sun is it possible to create a sun it is of course possible to make a sun although he's even have stars but it is not impossible on Earth because for


the simple reason that it takes the gravitational force is extremely weak and so it takes something like the size of a star to make fusion occur in the center well I I didn't mean on Earth I mean if you had to build like a second sun how did you do it you can't there's not enough hydrogen around yeah so the the limiting factor is the the just the hydrogen yeah I mean the the forces that an energy that it takes to assemble that is just mind-boggling all right so we would do that to be continued yeah to be continuous so what are we doing it with so in the one that I just described it's like you say so you have to replace this with some Force which is better than


that and so what I'd mean by is it's it's stronger than that so when I talked about the laser Fusion this is coming from the force which is enormous compared to gravity like like from the rocket action of pushing it together so in magnetic confinement we use another force of nature which is the electromagnetic force and that's very it's orders and Orders of magnitude stronger than the gravitational force and the key force that matters here is that if you have a Charged particle that namely it's a particle that has an electric net electric charge and it's in the proximity of a magnetic field then there is a force which is exerted on


that particle so this is called the Lowrance Force for those who are keeping track so that is the force that we use to replace physical containment so and so this again confuses how do you hold something at 100 million degrees it's impossible in a physical container this is not like you know it's not this plastic bottle holding in this liquid or a gas chamber what you're doing is they're using and you're immersing the fuel in a magnetic field that it basically exerts a force at a distance this comes back again to again like why plazas are so strange it's the same thing here and if it's immersed in this


magnetic field you're not actually physically touching it but you're making a force go onto it so that's the and that's the inherent feature of of magnetic confinement and then magnetic confinement devices are like a Toca Mac are basically uh configurations which exploit the features of that magnetic containment there's several features to it one is that the stronger the strength of the magnetic field the stronger the force and for this reason is that if you increase the strength of magnetic fields this means that the containment because namely the force which you're pushing against it is more effective


and the other feature is that there is no Force so for those magnetic fields what are these things they're also invisible but you know if you think of a permanent magnets or your fridge magnet there are there are field lines which we actually designate as arrows which are going around you sometimes see this in school when you have the you know the iron filings on a thing and you see the directions of the magnetic field lines or or when you use a compass right so that's telling you nor because we're living in an immersed magnetic field made by the Earth which is at very low intensity magnetic but it's strong enough we can actually see what


direction is so this is the arrow that the magnetic field is pointing it's always pointing North and for us is that so an interesting feature of this force is that there is no Force along the direction of the magnetic field there's only force in the directions orthogonal to the magnetic field so this by the way is a huge deal in in in in in in a whole other discipline of plasma physics which is like that the study of like our near atmosphere so the study of aurora borealis what's happening in the near atmosphere what happens when solar flares hit the magnetic in fact remember I said Fusion is the reason that life is responsible


in the universe where you could also argue so is magnetic confinement because the the charged particles which are being emitted from from the Galaxy and from our own star would be very very damaging to on Earth so we get two layers of protection one is the atmosphere itself but the other one is the magnetic field which surrounds the Earth and basically traps these charged particles so they can't get away it's the same it's the same it's the same deal how do you create a strong magnetic field yeah so with a giant magnet giant magnet yeah so it's it's basically true engineering there's essentially there's essentially two ways to create a magnet


so one of them is that we're familiar with like fridge magnets and so forth these are so-called permanent magnets and what it means is that Within These the atoms arranged in a particular way that it produces the electrons basically arranged in a particular way that it produces a permanent magnetic field that is set by the material so those 10 those have a fundamental limitation how strong they can be and they also tend to have this like circular shape like this so we don't use we don't typically use those so what we use are so-called electromagnets and what is this it's like um so the other way to make a magnetic field also go back to your you


know your your Elementary School physics uh or science class is that you take a a nail and you wrap a copper wire around it and connect it to a battery then it can pick up iron filings this is an electromagnet at its simplest what it is it's an electric current which is going in a pattern around and around and around and what this does is it produces a magnetic field which goes through it by the laws of electromagnetism so that's what an electro that's so that's how we make the magnetic field in these in in these configurations and the key there is that you it's not limited by the magnetic property of the material


the magnetic field uh amplitude is set by the amount of the the geometry of this thing and the amount of electric current that you're putting through and the more electric current that you put through the more magnetic field that you get the closest one that people maybe see is one of my one of my favorite skits actually was Super Dave Osborne on YouTube it's probably probably past years again a show called bizarre Super Dave Osborne which is a great comedian cult he was a stunt man and one of his tricks was that he was he gets into a car and then one of those things in the junkyard comes down you know and picks up the car and then puts it into the


into the crusher this is his stunt which is pretty hilarious anyway um but that thing that picks him up like how does that work that's actually not a permanent magnet it's a it's an electromagnet and so you can turn by turning off and on the power supply it turns off and on the magnetic field so this means you can pick it up and then when you switch it off the magnetic field goes away and the car drops okay so that's that's what it looks like speaking of giant magnets MIT and Commonwealth Fusion systems CFS built a very large high temperature superconducting electromagnet that was ramped up to a field strength of 20


Tesla the most powerful magnetic fields of its kind ever created down Earth because I enjoy this kind of thing can you please tell me about this magnet yeah sure oh it was it's fun yeah there's a lot to parse there so maybe uh we so we already explained an electromagnet which in general is what you do is you take electric current and you force it to to follow a pattern of some kind typically like a circular pattern around and around and around around it goes the more time the more current and the more times it goes around the stronger the magnetic field that you make okay and as I pointed out it's like really


important in magnetic confinement because it is the the force that's produced by that magnet in fact technically it goes like the magnetic field squared because it's it's a pressure which is actually being exerted on the plasma to keep it contained uh just just so we know for a magnetic confinement what is usually the geometry of the magnet what are we the geometry yeah so the geometry is typically that typically is what you do is you want to produce a magnetic field that Loops back on itself and the reason for this was goes down to the nature of the force that I described which is that there's no there's no


containment or Force along the direction of the magnetic field so here's a magnetic field in fact what what it's more technically or more graphically what it's doing is that when the when the plasma is here's plasma particles here there's a magnetic field what it does is it forces all those because of this this Lorenz force it makes all of those charged particles execute circular orbits around the magnetic field and they go around like this but they stream freely along the magnetic field line so this is why the nature of the containment is that if you can get that Circle smaller and smaller it stays further away from Earth temperature


materials that's why the confinement gets better but the problem is is that because it free streams along so we just have a long straight magnetic field okay it'll just keep leaking out the ends like really fast so you get rid of the ends so you basically Loop it back around so what these look like are typically donut shaped or more technically toroidal shape but donut shaped um things where this collection of magnetic fields Loops back on itself and it also for reasons which are more complicated to explain basically it also twists it also twists slowly around in this direction as well too so that's what it looks like that's what the


plasma looks like because that's what the fuel looks like so then this means is that the um the electromagnets are configured in such a way that it produces the desired magnetic fields around this so they precise does this have to be you were probably listening to our conversation with some of my colleagues yesterday so it's actually it's it depends on the configuration uh about how you're doing it the configuration of the plasma the configuration of the electromagnets and about how you're achieving this this requirement um it it's it's fairly precise but it doesn't have to be in particularly in


something like a Tokamak what we do is we produce planar coils that just mean they're flat and we situate them so if you think of a circle like this what does it produce if you put current through it it produces a magnetic field which goes through the circle like this so if you align many of them like this this this this this there's things online you can go see the picture to to you keep arranging these around in a circle itself this forces the magnetic field lines to basically just keep executing around like this so you tend to align that one tends to re well it requires good confine or good alignment it's not like in insane alignment


because you're you're actually exploiting the symmetry of the situation to to help it there's another kind of configuration of magnetic of this kind of magnetic confinement called a stellarator which is we have these names from for historic reasons which is different than a Taco Mac it's different than a token that actually works on the same physical principle that namely in the end it produces a plasma which Loops in magnetic fields which loop back on themselves as well but in that in that case the totality basically the totality of the confining magnetic field is produced by external three-dimensional magnets so they're Twisted


um and it turns out the Precision of those is is more stringent yeah so are taco Mac's by far more popular for research and development currently than Stellar Raiders of the concepts which are there of the token Mac is by far the most mature in terms of its breadth of performance and um and thinking about how it would be applied in a Fusion Energy System in the history of this was that many in fact you asked about if we go back to the history of the Plato science infusion center the history of fusion is that people scientists had started to work on this in the 1950s it was all hush-hush and


you know Cold War and all that kind of stuff and and it's like they realized holy cow they're like this is like really hard like we actually don't really know like what we're doing in this because everything was at low temperatures they couldn't get confinement it was interesting and then the the they Declassified it and this is one of the few places that the the west and the Soviet Union actually collaborated on was a science even during the Cold War even during the middle of the Cold War it was really and this actually perpetuates all the way till now for we we can talk about the the project that that is sort of


captured in now um uh but and and the reason they Declassified it is because like everything like kind of like sucked basically you know about trying to make this confinement in high temperature plasma and then the Russians then the Soviets right came along with this device called the Tokamak which is a Russian acronym which basically means uh magnetic coils arranged in the shape of a donut and and um they said holy holy cow like everyone was stuck at like a meager like half a million degrees or half a million degrees which is like in Fusion terms of


zero basically um and then they come along they say oh we've actually achieved a temperature 20 times higher than everybody else and it's actually started to make fusion reactions and everyone just go oh you know no way it's just hype from this it's like there's no way because we failed at this um it's a great story in the history of fusion is that then but this insisters said no look you can see this from our data it's like this thing is really hot and it seems to be working this is you know late 1960s and there was a uh there was a team that went from the United Kingdom's Fusion development lab and


they brought this very fancy amazing new technology called a laser and they use this laser and they shot the laser beam like through the plasma and by looking at the scattered light that came from the they go that basically the scattered light gets more broadened in its Spectrum if it gets hotter so you could you could exactly tell the temperature of this and even though you're not physically touching the plasma it's like holy cow you're right it is like it is 10 million degrees and so this was one of those explosions of like everyone in the world then wanted to build a token back because it was clearly like wow this is


like so far ahead of everything else that we tried before um so that actually has a part of the the story to MIT in the Plato science infusion center was why is there a strong Fusion in a major Fusion program at MIT it was because we were host to the Francis bitter magnet laboratory which is also the National High field magnet laboratory well you can see where this goes right from this you know we're kind of telling the stories backwards almost but you know the the the Advent of a Toca Mac along with the fact that you could makes very strong magnetic fields with the technology that had been developed at


that laboratory that was the origins of sort of pushing together the physics of the of the plasma containment and the magnet technology and put them together in a way that I would say is you know a very typical MIT success story right we don't do just just pure science or pure technology we sort of set up this intersection between them and there were several Pioneers that of of my of the of people at MIT like Bruno copy who's a professor in the physics department and Ron Parker who was a professor in electrical engineering and nuclear engineering it's like even the makeup of the people right has got this blends of Science and Engineering in them and


that's actually was the origin of the Plato science infusion center was was doing those things so anyway so back to this so why so yes tokamax have been have achieved the highest in magnetic Fusion by far like the the the best amounts of these of these conditions that I had talked about and in fact pushed right up to the point where they were near QP of one they just didn't quite get over one so can we actually just Linger on the uh on the collaboration across different nations just um yeah maybe looking at the philosophical aspect of this even in the Cold War there's something hopeful to me besides


the energy that these giant International projects are a really powerful way to ease some of the geopolitical tension even military conflict across Nations there's a war in Ukraine and Russia there's a brewing tension and conflict with China just the world is still um seeking military conflict cold or hot what can you say about sort of the lessons of the 20th century and these giant projects uh in their ability to ease some of this tension so it's it's a great question so as I said there was a reason because it was


so hard that was one of the reasons they they Declassified it um and actually they started working together in some sense on it as well too and I think it was really there was you know and are you ristic or or altruistic um aspect to this it's like this is something that could change you know the future of humanity and its nature and its relationship with energy isn't this something that we should work on together right and and and that went along in those ones and in particularly that any kind of place where you can actually have an open exchange of of of people who are sort of at the


intellectual frontiers of your Society this is a good thing right of being able to collaborate I've I've had the I mean I've had have had an amazing you know career I've worked with people from it's like hard to throw a dart at a country and on the map and not hit a country of people that I've been able to work with how amazing is that and and even just getting small numbers of people to bridge the cultural and societal societal uh um you know divides is a very important thing even when it's a very teeny action of the overall populations it can be held up as as an example of that but it's interesting that if you look at then that continued


collaboration which continues to this day is that it was it this actually played a major role in fact in East-West relations or like so Soviet West relations Is that um back in the uh the Reagan Gorbachev days which of course were interesting in themselves of all kinds of changes happening you know on both sides right um and but still like a desire to you know push down the stockpile of nuclear weapons and all that within that context there was um a very fairly significant historic event that at one of the the Reagan Gorbachev Summits is that they had really they didn't get there like they


couldn't figure out how to bargain to the point of the of the some some part of the tree dick anymore the details of it anymore but they needed some kind of a symbol almost to say but we're still going to keep working you know towards something that's important for all of us whether they pick a fusion project and that was in the mid-1980s and actually then after so they basically signed an agreement that they would move forward to like literally collaborate on on a project whose idea would be to show large net energy gain infusions commercial viability and work together on that and very soon after that Japan


joined as did the European Union and now um that project it evolved over a long period of time and had some interesting political ramifications to it but in the end this actually also had South Korea India and China join as well too so you're talking about make major a major fraction of and now Russian of course instead of the Soviet Union um and actually that Coalition is holding together despite the obvious political you know uh turmoil that's going around on all those things and that's a project called eter which is in under construction in the south of France right now can you actually before we return to the giant magnet and maybe


even talk about spark and this stuff going to all amazing stuff going on at MIT what is theater what what is this International nuclear fusion Mega project uh being built in this in the south of France so it's scientific purpose is a worthy one then it's essentially an any Fusion device the thing that you want to see is more and more relative amounts of self-heating and this is something that had not been seen although although we have made Fusion reactions and we'd seen small amounts of the self-heating we never got to a dominant this actually goes to this QP business okay the goal of eater and it shifted around a little


bit historically but very you know fairly quickly became we want to get to a large amount of self-heating so this is why it has a its primary feature is to get 2qp of around 10 and through this this is a way to study this plasma that has more higher levels of self-determination around on it but it also has another feature which was let's produce fusion power at a you know relevant scale and and actually they're linked together which actually makes sense you think about it is that because the fusion power is the heating Source itself this means that they're linked together and so either makes it is projected to make


about 500 million watts of fusion power so this is a significant amount like this is what you would use you know for powering cities so it's not just the research that really it is the development of really trying to achieve scale here so self-heating and scale yeah yes so this this meant then too is the the development of an industrial base that can actually produce the Technologies like the electromagnets and so forth and to do it with it is a Tokamak it is it is one of these yes but very interesting it also revealed limitations of of this as well too well it is it's interesting is that it is clearly a


um on paper and in fact in in practice as well too the world the world you know and very different political systems and you caught you consider at least geopolitical or economic rivals or whatever you want to use like working towards a common cause and one that we all think is Worthy is is very like okay that's very satisfying but it's also interesting to see the limitations of this it's because well you've got seven you know chefs in the kitchen so what is this what does this meant in terms of the speed of the project and the ability to to govern it and so forth it's just been a challenge uh honestly around this and this is I mean it's very


hard technically what's what's occurring but when you also introduce such levels of I mean this isn't just me saying it there's like GAO reports from the US government and so on this is It's hard to like steer all of this around um and what that's tended to do is make it it's it's not the fastest decision making process you know my own personal view of it was it was it was interesting because you asked me you said about the magnet and Commonwealth Fusion systems it was I worked most of my career on eater because when I came into the field in the early 1990s when I completed my PhD and started to work this was one of the most like you can't imagine being


more excited about something like we're going to change the world with this project we're going to do these things and we just like Port like an entire generation and afterwards as well too is just poured their imagination and their creativity about making this thing work very good but at also at some point though when you know when it got to being another five years of delay or a decade of delay you start asking yourself well is this what I want to do right am I going to wait for for this so it was a part of me starting to ask questions with my students I was like is there another way that we can get to this extremely worthwhile goal that


maybe maybe it's not that that maybe it's not that pathway and the other part that was clearly frustrating to me because I I'm an advocate of fusion you asked me about was I you know I was like well it's laser Fusion or inertia or inertial Fusion or magnetic Fusion I just want Fusion Energy okay because I think it's so important to the world is that but the other thing if that's the case then why do we have only one attempt at it on the entire planet which was either it's like that makes no sense to me right we should have multiple attempts at this with different levels of whatever you want to think about a


technical schedule scientific risk which are Incorporated in them and that's going to give us a better chance of actually getting to the goal line with that Spirit your leading mit's effort to design spark a compact High field DT burning takamak how does it work what is it what's the motivation uh what's the design what are the ideas behind it yeah at its heart it's exactly the same concept as eater this is basically a configuration of electromagnets it's arranged in the shape of a donut and within that we will do we would do the same thing that happens in all the other token Max and including an eater and in this one is


that namely you put in gas make it into a plasma you heat it up it gets about 100 million degrees the differentiator in spark is that we use the actual deuterium tritium Fuel and because of the access to very high magnetic fields it's in a very compact space it's very very small what I mean by small so it's 40 times smaller in volume than either but it uses exactly the same physical principles so this comes from the high magnetic field so in the end like what is why does this matter what it does is it does those things and it should get to the point where it's producing over 100 million watts of fusion power


but remember it's 40 times smaller so either was 500 megawatts technically our design is around 150 megawatts so it's only about a factor of three difference despite being 40 times smaller um and we see um QP large order of 10 or something like this at that at that at that state is very important scientifically because this is basically matches what eater is looking to do the plasma is dominated by its own heating that's very very important and it does that for about 10 seconds and the reason it's for 10 seconds is that in terms of that that basically allows everything to settle in terms of


the fusion in the plasma equilibrium everything is nice and settled so you know you have seen the physical state at which you would expect a power plant to operate basically for for magnetic Fusion like wow right but it's more than that and it's more than that it's because about who's building it and why and how it's being financed um so that scientific pathway was made possible by the fact that we had access to a next generation of magnet technology so to explain this real quick why do we call it you you said it in the words a superconducting magnet what does this mean


superconducting magnet means that the materials which are in the electromagnet have no electrical resistance therefore when the electric current is put into it the current goes around unimpeded so it could basically keep going around and around you know technically for infinity and what that means are for eternity and what that means is that the um when you energize these large electromagnets they're they're using basically zero electrical power to maintain them whereas if you would do this in a normal wire like copper you basically make an enormous toaster oven that's consuming enormous amounts of power and getting hot which is the problem that was the


technical breakthrough that was realized by myself and at the time my students and postdocs and colleagues at MIT was that we we saw the Advent of this new this new superconducting material which would allow us to access much higher magnetic fields is basically the next generation of the technology and um and it was quite disruptive diffusion that namely what it would allow that if we could if we could get to this point where we can make the round 20 Tesla We Knew by the rules of tokamax that this was going to be is going to allow us to vastly shrink like the sizes of these devices so it wouldn't take um although although it's a worthy goal


it wouldn't take a seven nation International you know treaty basically to build it you could build it with a company and a university it's the same kind of design but now using the superconducting magnets yeah and if in fact if you look at it's like it's if you just expand the size of it they're like they look almost identical to each other because it's based on the and actually that comes for a Reason by the way is that it also looks like a bigger version of the Toca Mac that we ran at MIT for 20 years where we established the scientific benefits in fact of these higher magnetic fields so that's the pathway that runs so always say so what


does this mean the context is different because it was made because it's primarily being made by a a private sector company spun out of MIT because the way that it raised money and the purpose of the entity which is there is to make commercial fusion power plants not just to make a scientific experiment this is actually why we have um that's why we have a partnership right is that our purpose at MIT is not to commercialize directly but boy do we want to advance the technology and the science that comes along this and that's the reason we're sort of doing it


together so it's MIT and Commonwealth Fusion systems so what's what's interesting to say about financing and this seems like from a scientific perspective maybe not an interesting topic but it's perhaps an extremely interesting topic I mean you can just look at the testing between SpaceX and NASA for example yes it's just clear that there's different financing mechanisms can actually significantly accelerate the development of Science and Engineering it's great that you brought that up we use several historic analogs and one of them is around SpaceX which is an


appropriate one because space you know putting things into orbit has a just a has a minimum size to it and integrated technological complexity and budget and things like this so you know our point when we were like talking about starting like a fusion commercialization you know company people look at you like like isn't this still really just a science experiment you know but are one of the things that we pointed to was SpaceX to say well tell me like 25 years ago how many people would have voted that you know the the leading entity on the planet to put things into orbit it's a private company people would have thought you were not so right it's like


and what is interesting about SpaceX was that it proved it's more than actually just financing it's really the purpose of the organization so the purpose of a gun and I'm not against Public Finance or anything like that but the purpose of a public entity like in like NASA correctly you know speaks to the political because because the cost comes from the political you know uh assembly that is there and and I guess from us eventually as well too but its purpose wasn't about like making a commercial product it's about fundamental Discovery and so forth which is all which is all really great


it's like why did why did SpaceX it's interesting because why did SpaceX succeed so well is because the idea was it's like the the focus that comes in the idea that you're going to relentlessly like reduce cost and increase efficiency is a drive that comes from the commercial aspect of it right and this also then changes um the people in the teams which are doing it as well too and in fact trickles throughout the whole thing because the purpose isn't while you're while you're advancing things like it's really good that we can put things in orbit a lot less more cheaply like in advance of science which is an


interesting Synergy right and it's the same thing that that we think is going to happen in fuse that namely these this is a bootstrap effect that actually that when you start to push yourself to think about near-term commercialization it like allows the size to get in hand faster which then allows the commercialization to go faster into an up we go by the way we've seen this also in another like again it's a you have to watch out with with analogies because they only can go so far but like biotech is another one like you look at the Human Genome Project which was it's sort of like it's it to me that's like like mapping the human genome is


like like that we can make net energy from Fusion like it's one of those like in your drawer that you go this is a significant achievement by Humanity right in the century and there's the Human Genome Project fully government funded it's going to take 20 25 years because we basically know the technology we're just going to be really diligent keep going and then all of a sudden what comes along disruptive technology right you can sequence you you know shotgun sequencing and computer you know recognition patterns and basically oh I can do this a hundred times faster like wow right and so so that's really the uh you know to me that the story


about why we started why we launched Commonwealth Fusion systems was more than just about another source of funding which is a different source of fun because it comes it's also a different purpose which is very important but there's also something about a mechanism that creates culture so giving power to like a young student ambitious student to have a tremendous impact on the progress of nuclear fusion creates a culture that actually makes progress more aggressively like like you said when Seven Nations collaborate it gives more incentive to the bureaucracy to slow things down to kind of have let's have first have a discussion and


certainly don't give voice to the young ambitious Minds that are really pushing stuff forward yeah and there's something about like the private sector that rewards encourages inspires young minds to say in the most beautiful ways Fu to the just for the boss yeah just to like we'll make it faster we'll make it simpler we'll make it better we'll make it cheaper yeah and sometimes that brashness doesn't bear out you know that's an aspect that you just take a different risk profile as well too but you're right it's this you know of them I mean it was interesting our our own trajectory at the at the fusion Center


was like we were pushed into this place by necessity as well too because I told you we have and we had operated for a long time a Tokamak at uh on the MIT campus achieve these World Records like 100 million degree plasma and so I was like wow this is fantastic but you know somewhat ironically I have to say is that it was like oh but we're not this isn't the future of fusion anymore like we're not we're just gonna stop with small projects because it's too small right so we should need we need to really move on to these much bigger projects because that's really the future of fusion and so it was defunded um and this basically put at risk like


like we were going to essentially lose MIT in the ecosystem really a fusion both from the research but also clearly important from the educational part of it so we you know we push back against this we got a Lifeline we were able to go it was in this it was in this time scale that we basically came up with this idea it's like we should do this and in the end it was all of those the the people who were in the sea level of the company were all literally students who got caught in that they were PhD students at the time so you talk about enabling another generation it's like yeah there you go right so spark gave a lifeline


but it's way more than that it was it wasn't just about like surviving for the sake of surviving it was like in the end for me it became like this I remember the moment when you talk about these moments as a scientist and we were just like we were working so hard about figuring out like does this really would this really work like in this it's complex like does the magnet work does the interaction with the plasma work does all these things work and it was just a grind push push push push and I remember the moment because I was sitting in my office in Brookline and and and and there was just like I read like and


I was in I don't know whatever the 20 or 40th slide or something into it and it was sort of that moment like it just came together and I like I I got I couldn't even sit down because all I was just like my wife was like why are you walking around the apartment like this like I just couldn't she I said it's going to work like it's going to work like holy that moment of realization is like kind of amazing but it also brings the responsibility of making it work as well so you mean like that magic realization that you could have this uh this modern uh Magnum technology and you can actually like why do we need to work with either we can do it here yeah yeah


but it's interesting that eater is um that one one of one of the reasons that like that we started with a group of six of us at MIT and then it's once we got some funding through the through the establishment of the company it became a slightly larger but in the end we had a rather small team like this was like a a team of order of like 20 to 25 people design spark and like a like about two years right how does that happen well we're clever but you have to give eater it's due here as well too that again this is an aspect always of the bootstrap up like I go back to the Human Genome Project so modern day genomics would not be possible without


the underlying basis that came from setting that up it had to be there it had to be curiosity driven public program is the same with either but we because we had the tools that were there to understand either we also have the tools to understand spark so we we parlayed those in an extremely powerful way to be able to tell us about what was going to happen so these things are never simple right it's like people look at this go oh this means we should like should we really have a public-based program about Fusion or should we have it all in the private it's like no no the answer is neither way because in all these complex Technologies you have to


keep pushing on all the fronts to actually get it there so you know the natural question when people hear breakthrough with the with the inertial confinement with the magnetic confinement is so when will we have commercial yeah um reactors power plants that are actually producing electricity what's your sense um looking out into the future when do you think you can Envision a future what we have actual electricity coming from nuclear fusion partly driven by us but in other places as well too so there's the Advent what's you know what's so


different now than three or four years ago like we launched around four years ago what's so different now is is the Advent of a very nascent but seemingly robust like commercial Fusion you know Endeavor so it's not just Commonwealth Fusion systems there's something like 20 plus you know companies there's a sector now there's a sector they actually they actually have something called the fusion industry Association which if your viewers want to go see this this describes the difference and they've got this plethora of approaches like I haven't even described all the approaches I've basically described the mainline approaches


um you know and they're all at varying degrees of Technical and scientific maturity with very huge different you know balances between them but what they share is that because they're going out and finding getting funding from the private sector is that their stated goals are about getting fusion into place so that both it meets the investors demands which are interesting right in the time skills of that but also it's like well there's going to and why it's because it's easy there's gonna there's this enormous push driver about getting carbon-free energy sources out into the market and whoever


figures those out is going to be both very it's going to be very important geopolitically but also economically as well too so it's a different kind of a bat I guess or a different kind of gamble that you're taking with Fusion but it's so disruptive that it's like there's there's a essentially a class of investors and teams that are ready to go after it as well too so what do they share in this they typically share um getting after Fusion on a time scale so that could it have any relevance towards climate change baling climate change and I would say this is difficult but it's it's fairly easy because it's math so what you do is you actually go


to some Target like 20 50 or 2060 something like this and say I want to be blank percent of the the world's market of electricity or something like that and you and we know historically what it takes to evolve and distribute these kinds of Technologies because every technology takes some period of time so-called s-curve it's basically everything follows a logarithmic exponential type curve it's a straight line a log plot and um like you look at winds solar fission they all follow the same thing so it's easy you take that curve and you go that slope and you work backwards and you go if you don't start in the early 2030s like


it's not going to have uh you know it's not going to have a significant impact by that time so all of them share this idea and in fact it's not just the companies now the U.S federal government has a program that was started last year that said we should be looking to try to get like the first and what I mean by like what does it mean to start that you've got something that's putting electricity on the grid a pilot what we call it and if that can get started like in the early 2030s you know the idea of ramping it up you know makes sense that's math right so that's the ambition then the question is and and actually this is different because the government


program and that they vary around in this so for for example the United Kingdom's government idea was to get the first one on by 2040. and China has Ambitions probably middle 2030s uh or maybe a little bit later and Europe uh you know Continental Europe is it's a little bit I'm not exactly sure where it is but it's like later it's like 2050 or 2060 because it's mostly linked to the eater timeline as well too um the fusion companies which makes sense it's like of course they've got the most aggressive timelines it's like we're going to map the human genome faster as well too right so it's interesting about where we are and I


think you know my we're not all the way there but my intuition tells me we're probably going to have a couple of cracks at it actually uh on that timeline so this is where we have to be careful though you say commercial Fusion you know what does that mean commercial Fusion to me means that you're actually have a known quantity about what it costs what it costs to build and what it costs to operate the reliability of putting energy on the grid that's commercial Fusion it's like so it turns out that that's not not necessarily exactly the first Fusion devices that put electricity on the grid because you got it there's a learning curve to get


like better and better at it but that's probably I would suspect the biggest hurdle is to get to the first one the work I've done uh the work I continue to do with autonomous vehicles and semi-autonomous vehicles there's an interesting parallel there where a bunch of companies announced a deadline for themselves in 2020 21 22 and only a small subset of those companies have actually really pushed that forward this Google with waymo or alphabet rather uh is do and and then there's uh uh Tesla with semia Thomas driving in their autopilot full self driving mode and those are different approaches so Tesla is achieving much much higher


scale but the sort of the quality of the drive is semi-autonomous right I I don't know if there's a metaphor or an analogy here and then there's waymo that's focusing on very specific cities but achieving real full autonomy with actual passengers but the scale is much smaller so I wonder like just like you said there would be these kinds of similar kind of really hard pushes absolutely so actually this is what I it's why I'm encouraged about Fusion now so Fusion is still hard let's let everyone be clear because of the signs under underneath it of us of achieving the right conditions for the plasma basically is a is a is a yardstick that you have to put up


against all of them what's encouraging that I see in this and it's actually what happens when you sort of let loose the creativity of this is maybe I'll go back to First principles so Fusion is a also a fairly strange so if you think about building a coal Point like burning wood and coal and gas is actually not that much different from each other because they're kind of about the same physical conditions and you get the fuel and you light into the fusion is very remember I told you that there's this condition of the temperature which is kind of universal but if you take the density of the fuel between magnetic fusion and inertial


fusion they're different by about a factor of 10 billion so this and the density fuel really matters that actually so does the this means energy confinement time is also different by a factor of 10 billion as well too because it's the product of those two so one's really dense and short lived and the other ones really long-lived and and actually under dense as well too so what that means is that the way to to the the way to the to get the underlying physical state is so different among these different approaches what it lends itself to is does this mean that eventual commercial products will


actually fill different needs in the energy system so it sort of goes to your comment about because anything that is high tech and is like a really important thing in our economy tends to never find its way as one only one manifestation like look at Transportation as well too we have scooters Vespas you know uh Overland trucks cars electric cars of course we have these because they meet different demands in it so what's interesting you know that I find fascinating now is that we have infusion it's going to look like that that probably there's the while the near-term focuses on electricity


production there might even be different kinds of markets that actually make sense in some places less than others it comes to trade-offs because we haven't really talked about the engineering yet but engineering really matters like to them to the operation of the device and so it could be um that that you know I suspect what we'll end up with is several different configurations which have different features which are trade-offs basically in in the energy Market whether he says the major engineering or general hurdles yeah that are in the way yeah um so the first one is just the cost of


building a single unit so Fusion has and is actually interesting you talked about the about the different models that you have so Fusion has um one of its interesting limitations is that it's very hard almost at some point becomes physically impossible to actually make small power units like a kilowatt a thousand Watts you know which is like a personal home like you know this is about a thousand dollars or your personal use of an energy of electricities but like a thousand Watts um this is basically impossible and if


for a single you know unit to do this um so like you're not gonna have a fusion like power plant like is your furnace in or your electric heater in your home and the reason for this comes from the fact that Fusion relies on it being it's not just that it's very hot it says that the fusion power is the heating source to keep it hot so if if you get if you go too small it basically just cannot keep it hot that's um so it's interesting is that this so this is one of the hard parts so this means that the individual units you know and it's it varies from concept to concept but the the national academies report that came out last year sort of


put the Benchmark as being like probably the minimum size looks like around 50 million watts of electricity which is like another for like a meat like a small to you know mid-sized City actually um so that is so that's sort of like a scale Challenge and in fact it's one of the reasons why in Commonwealth and another private sector ones like we they try to push this down actually of trying to get to the to these smaller units just because it reduces the cost of it um then probably um obviously I would say it's an obvious one like achieving the fusion State itself and High Gain Is is a hard one


what we already talked about what kind of harder what kind of challenges that that's achieving the right temperature density and energy confinement time in the fuel itself in the plasma itself and so some of the so some of the the configurations which are being chosen have are actually uh I have quite a ways to go in fact I've seen those but what their their consideration is oh yes but by our particular configuration the engineering Simplicity confers like an economic Advantage even if we're behind in sort of an assigned sense okay which is fine this is also what you get when you get a an explosion in in the private sector you basically are Distributing


risks in different ways right which makes sense um all of that good that so what I would say is that the the next hurdle to really overcome is is about making that electricity so like we need to see a unit or several units like put using Fusion in some way to put a meaningful amount of energy on the grid because this starts giving us real answers um as to like what this is going to look like the full end to end the full end-to-end thing so Commonwealth's goal is that I'll I'll just comment to Commonwealth because I'll take some you know some I get some credit for this is that the the origins of Commonwealth


were in fact in examining that like we could see this new technology coming forward this this new superconducting material and the origins of our thought process were really around designing effectively the pilot plant or the commercial unit it's called Arc which is actually the step forward after spark and that was the orig the origins of it so all the things that were other parts of the plan like spark and the magnet were actually all informed totally by building something that's going to put net electricity on the grid and the timing of that we still hope is actually the early 2030s so spark is the design of the takamakan arc as the actual full


and thing it's like a thing that actually puts the energy on the grid so spark is named you know intentionally that it's like it's on for a short period period of time and it doesn't have a it has yeah yeah you know it's the spark of the fusion you know Revolution or something like that I guess we could call it um yeah so those are those are so those are sort of the programmatic challenges of doing that and um you know it's interesting you asked about you talked about SpaceX so what has evolved even in the last year or so was in fact in March of 2022 the White House announced that it was going to


start a program that kind of looks like a SpaceX analogy that namely wow we've got these things in the private sector we should leverage the private sector and the advantages of what they obtain but also with the things like this is going to be hard and it's going to cut it's going to take quite a bit of financing so why don't we set up a program where we don't really get in the way of the private sector Fusion companies but we help them Finance these difficult things which is how SpaceX basically became successful through the cots program fantastic right and that's evolving as well too so like the fusion ecosystem is almost unrecognizable from


where it was like five years ago around those things how important is it for the heads of the companies that are working on nuclear fusion to have a Twitter account and to be quite you said you don't use Twitter I don't use that much I mean there there is some element to and I don't think this should be discounted whatever you think about uh figures like Jeff Bezos uh with blue origin or Elon Musk or SpaceX there is a science communication yeah to put it uh in nice terms that's kind of required to really educate the public and get everybody excited and sell the sexiness of it I mean just even the videos of


SpaceX just being able to kind of get everybody excited about going out to space once again I mean there's all kinds of different ways of doing that but part I mean I guess most of the companies do well you know is is to advertise themselves to really sell themselves it is yeah well actually it's like I feel like one of the reasons on this podcast and so like I I don't have an official role in the company and one of the reasons for for this was also that it's interesting because when you come from like you're running a company it's it makes sense they're promoting their own product and their own Vision which totally makes sense but there's


also a very important role for academics who have knowledge about what's going on but are sufficiently distant from it that they're not fully only so self-motivated just by their own you know projects or so forth and for me this is I mean we we see particularly the problems of the distrust in technology um and then honestly in the scientific Community as well too it will be that one of the greatest tragedies I would say that if we go through all of this and almost pull off what looks like a miracle like Technologic and scientific wise which is to make a fusion power plant and then nobody wants to use it


because they feel that they don't trust the people who are doing it or the technology so we have to get so far out ahead of this like so I give lots of public lectures or things like this of of accessing a larger range of people we're not trying to hide anything you can come and see you know come do tours of our laboratory in fact I want to set those up virtually as well too you might look at our plasma size infusion center YouTube channel so we are reaching out through those meetings and it's really important that we do those things but it's also but also then realizing setting up the realistic expectations of what we need to do you know we're not


there like we don't have commercial Fusion devices yet and you ask like what are the challenges I'm not going to get in into any deep technical you know questions about what the challenges are but it is it the pathway not just to make fusion work technically but to make it economically competitive and viable so it is actually used out in the private sector is a non-trivial task and it's because of the newness of it like we're simultaneously trying to evolve the technology and make it economically viable at the same time those are two difficult couple tasks so my own my own research and my own drive right now is at Fantastic Commonwealth


Fusion systems is set up we have a commercialization unit of that particular kind which is going to drive forward a token Mac in fact I was just there there's discussions or there's there's dialogues going on around the world with other kinds of ones like Stellar Raiders which prefer different kinds of challenges and economic advantages but what we have to I know what we have to have what we have to have is a new generation of integrated scientists technologists and Engineers that understand like how what needs to get done to get all the way to the goal line because we don't we don't have them now like a multi-disciplinary yeah


exactly what's required I mean you've spoken about uh you've said that Fusion is quote the most multi-disciplinary field you can imagine yes yeah why why is that what are the yeah well because because most of our discussion that we've had so far is really like a physics discussion really so which don't don't neglect physics is at the for origin of this but I've already we touched on plasma physics and nuclear physics which are basically two you know somewhat overlap but independent disciplines then when it comes to the engineering it's almost everything so so why is this well let's build let's build an electromagnet


together okay what is this going to take it's going to take um it's basically electrical engineering computer and so you under understand what how it goes together and what happens computational engineering to model this very complex integrated thing materials engineering because it's this you're pushing materials to their limit with respect to stress and so forth takes cryogenic engineering which is sort of a sub-discipline but cooling things to extremely low temperatures probably some kind of chemistry thing in there too well actually yeah which tends to show up in the materials and that's just one of the sub components of it


like almost everything gets hit in this right so you're and you're also in a very integrated environment because in the end all these things while you isolate them from each other in a physics sense in an engineering sense they all have to work like seamlessly together so it's one of those I mean in my own career I've basically done Atomic physics spectroscopy you know plasma physics uh iron etching um so this includes Material Science um uh something called mhd even magnetohydrodynamics and now all the way through like I I'm not even sure how


many different careers I've had it's also by the way this is also an um a recruiting stage for like young scientists thinking to come in like my comment to sign is if you're bored in Fusion you're not paying attention because there's always something interesting to go and and do so that's a really important uh part of what we're what we're doing which isn't new in Fusion actually and in fact is in the roots of of what we've done at MIT but holy cow like the proximity of of possibility of commercial Fusion is the new thing you know so my catchphrases like you might be wondering like why aren't we doing all these


things like why weren't we pushing towards economic fusion and new materials and new methods of heat extraction and so forth because everybody knew Fusion was 40 years away and now it's four years away there is a history like you said 40 30 whatever that kind of old joke uh there's a history of fusion projects that you know are characterized by cost overruns and delays um how do you avoid this how do you minimize the chance of this you have to build great teams um uh is one of them it tends to be that the smaller the there's sort of like I'm not an expert in this but I've seen this


enough integrated certain equations yeah well there's almost there's there's I've seen this from enough teams like I've seen also the futility of Lone Geniuses trying to solve everything by themselves like no but also organizations that have 10 000 people in them is is just not doesn't lend itself at all to Innovation so like one of our original sponsors and a good friend vinod Coast I don't know if you've ever talked to the node Coastal he's a venture guy he's got fantastic ideas about like the right sizes of teams and things that really innovate right and and there is an Optimum place in there is that you get enough cross-discipline and ideas but it


doesn't become so overly bureaucratic that you can't execute on it so so one of the ways and this was one of the challenges of fusion is that everything was leading towards like I have to have like ex enormously large like teams just to execute because of the scale of the project the fact that now through technology through both technology and the argue financing Innovation we're driving to the point where it's smaller focused teams about doing those things so that's one way to make it faster the other way to make it faster is modularize the problem or parse the problem so this is the other difficulty infusion is that it you know you tend to


look at this that's like oh it's it's really just about making the plasma into this state you know here that you get this energy gain no because in the end if you can parse out the different problems of making that and then make it as separate as possible from extracting the energy and then converting it into electricity the more separate those are the better they are because you get parallel pass that basically mitigate risk this is not new infusion by the way and this is the way that we attack most complex technology logical you know integrated technological challenges have you uh by any chance seen some of the application of


artificial intelligence reinforcement learning a deep mind has a nice paper has a nice effort um on basically using reinforcement learning for learn control algorithm for for controlling nuclear fusion yeah um do you find those kinds of I guess you throw them under the umbrella of computational modeling do you find those interesting promising directions they're all they're all interesting so when people you know I'll pull back maybe a a natural question is like why is it different in Fusion like there's a long history diffusion right it was going on for like I told you like stories from the late 1960s like what's different now


right so I I think from the from the technology point of view there's two massive things which are different so one of them you know I'll be parochial it's the Advent of this new superconducting materials because the most mature ways that we understand about how we're gonna get the fusion power plants or magnetic fusion and by the fact that you've got access to something which like changes the economic equation by an over and Order magnitude is just a totally you know and that that wasn't that long ago was only September of 2021 we actually demonstrated the technology that changes the the prospects there and the other


one is Computing and it's across the whole Spectrum it's not just in control of the fusion device it's actually in in the we actually use machine learning and things like this in the design of the magnet itself it's an incredibly complex design space so you use those tools the simulation of the plasma itself is actually we're at a totally different place than we were because of those things so those are the two big drivers that I see actually that make it different uh and actually and it's interesting both those things self enforce about what you asked about before like how do you avoid delays and things well it's by having smaller teams


that can actually execute on those but now you can do this because the new magnets make the devices all smaller and the Computing means your Cuban Effectiveness about exploring the optimization space is way better it's like they're all Interlink to each other plus the modularization like you said and so everything just kind of works together to make smaller teams more effective move faster and it's actually and it's through that learned experience I mean you know of the things that I'm the most proud of about what came out in fact the origins of thinking about how we would use the the the high temperature superconducting magnets came


out of my design class at MIT and in the design class like one of the features that I kept I mean it was interesting I actually learned I really learned along with the students about this but like this insistence on the features like we can't have so many coupled integrated hard technology developments like we have to separate these somehow so we worked and worked and worked at this and in fact that that's what really in in my opinion the greatest advantage of the arc design and when it com you know and and built into the Commonwealth Fusion system idea is like to parse out the problems like how can we attack these in parallel


um yeah and so it really comes to we talked about philosophy it's like a design philosophy like how do you attack these these kinds of problems and you know you do it like that and also like you mentioned Offline that there's a power to you know as part of a class yeah to decide a nuclear fusion uh and it's it's hard to imagine a more powerful force than like 15 MIT PhD students like working together towards solving a problem and what I always in fact we just we recently just taught the the most recent you know I say I teach it I mean I I guide it actually the most recent version of this where they


actually designed you know based on this National academies report they actually designed like the pilot plant that has bases and similarities to what we had done before but you know I kept wanting to like push the envelope and where they are it's like the creativity and the uh and the the energy that they bring to these things is kind of like it keeps me going like us you know I'm not gonna retire anytime soon when I keep seeing that kind of dedication and it's wonderful around on that um it almost not to overuse a um uh uh or to paraphrase something right which is that you know the the famous um uh quote by Margaret Mead you know


never doubt that a small group of dedicated you know persons will change the world indeed it's the only thing that ever has I mean that's just such a powerful and inspiring thing for an individual find the right team be part of that and then you yourself your passion your efforts could actually make a big change yeah a big impact I I gotta ask you so it's uh it's a whole nother different conversation I'm sure to have but uh uh nuclear power as it currently stands so using uh fission uh is extremely safe despite public perception it is the safest actually so that's a whole nother conversation but almost like a human


bureaucratic physics engineering uh question of what lessons do you draw from the um catastrophic events where they uh the the power plants did fail so Chernobyl and Three Mile Island Chernobyl what lessons do you draw three by London wasn't really a disaster because nothing escaped from the thing but Chernobyl and Fukushima were have been you know had obvious consequences in the populations and that live nearby what lesson do you draw from those that you can carry forward to Fusion now I know there's you can say that you're not going to have


the same kind of issues but it's possible that the same folks also said they're not going to be have those same kind of issues yeah we humans the human factor we haven't talked about that one quite as much but it's still there so to be clear it's so Fusion has the intrinsic safety with respect to it can't run away those are physics bases Technology and Engineering basis of running a complex again anything that makes large amounts of power and heats things up is got intrinsic safety in it and by the fact that we actually produce very energetic particles this doesn't mean that there's no radiation involved in ionizing radiation to be more


accurate infusion it's just that it's in a very different order of magnitude basically so what are the lessons uh in in Fusion so so one of them is make sure that you're looking at aspects of the holistic environmental and societal footprint that the technology will have as technologists we tend not to focus on these and particularly in early stages of development like we just want something that works right but if we if we come with just something that works but doesn't actually satisfy the societal demands for safety and for dispose I mean we will have materials that we have to dispose of out of fusion just this is but there's technological


questions about what that looks like so will this look like something that you have to you know put in the ground for 100 years or five years like and the consequences of those are both economic and societal acceptance and so forth but don't bury those like put the bring these up front talk to people about them and make people realize that you're actually you know the way I would look is that you're making Fusion more economically attractive by making it more societally except as well too and then realize is that you know I think there's a few interesting you know boundaries basically this so one of them speaking of boundaries that successful


Fusion devices I'm pretty sure will require that you don't have to re have an evacuation plan for anybody who lives at the site boundary so this has this has implications for what we build from a fusion engineering point of view but has major implications for where you can cite Fusion devices right so in many ways it becomes more like well you know we have fences around you know industrial heat sources and things like this for a reason right for personal safety it looks more like that right it's not quite as simple as that but that's what it should look like and in fact we have research projects going on right now at MIT that are like trying


to push the Technologies to make it more look like that I think that those are key and then in the end as I said like so Chernobyl is physically impossible actually in an effusion system I'm a physics from a physics perspective you can't run away like it did at Chernobyl which was basically human error that you know of letting letting the reactors like run out of control essentially the human error can still happen nuclear with Fusion basically yeah so but in that one if human error occurs then it just stops and this is done and all of those things this is the requirement of of us as technologists and and


developers of this technology to not ignore that dimension in fact of the design and that's why me personally I'm actually pouring myself more and more into that area because this is going to be I actually really think it is an aspect of the economic viability of fusion because it clearly differentiates ourselves and also sets this up to be about what we want Fusion to be is that again on paper Fusion can supply all of our energy like all of it so this means I want it to be like like really environmentally benign but this takes engineering Ingenuity basically to do that let me ask you some wild out there questions sure so first


we've been talking too much you know [Laughter] simple uh practical things in everyday life no the only revolutionizing the entire energy infrastructure of human civilization yes but um so cold fusion yeah this this idea this dream uh this interesting physical goals seemed to be impossible uh but perhaps it's possible do you think it is possible do you think down the line somewhere in um in the far distance as possible to achieve Fusion at a low temperature it's very very very unlikely and this comes from so this would require a


pretty fundamental shift in our understanding of of physics like as we know it now and we know a heck of a lot about how nuclear reactions occur um but by the way what's interesting is that there's they actually have a different name for it they call it leaner like low energy nuclear reactions but we do have low energy nuclear reactions we know these it's because these come from particularly the weak interaction the weak Force nuclear force and so it's at this point um you know as a scientist you always keep yourself open because but you also demand proof right and that's the thing


it almost requires a breakdown on the theoretical physics side so something some deeper understanding about quantum mechanics something so the quantum tunneling some some weird yeah and that and and people have looked at that but even like something like Quantum tunneling has a limit as to what it can actually do so there there are people who are genuine you know that really want to see it make it but you know sort of goes to the extraordinary I mean we know Fusion happens at these high energies like this when we know this extremely accurately and I can show you a plot that shows that as you go to lower lower energy it basically becomes


immeasurable so if you're going down this other pathway it means there's really a very different physical mechanism involved so all I would say is that I I actually poke in my head once in a while to see what's going on and that area um and as scientists we should always try to make ourselves open um and uh but in this one it's like but show me something that I can measure and that it's repeatable and then and then it then it's going to take more extraordinary effort and to date this has not met that threshold in my opinion so I'm even more so than just mentioning or in that question thinking about


people that are claiming to have achieved cold fusion I'm more thinking even about people who are studying black holes and they're they're basically trying to understand the function of you know theoretical physicists that are doing the Long Haul yeah trying to investigate like okay what is happening at the singularity what is uh this kind of uh holographic projections on a plate these weird freaking things that are out there in the universe and like somehow accidentally they start to figure out something weird yeah and then all of a sudden there's weirdness all over the


place already yeah somehow that weirdness will yeah I think in a time scale probably of a hundred years or so that weirdness will open uh it just seems like nuclear fusion and black holes and all of this are two they're next door neighbors a little bit too much for like you'll find something yeah interesting let me tell you a story about this yes okay it's a real story okay so they're a really really clever scientists in the in the end of the late 1800s in the world you talk about like James cork Maxwell when you talk about Lord Calvin and you talk about Lawrence actually who named after these other


ones and you on and on and on and like Faraday and they discovered electromagnetism holy cow and it's like they figure out all these things and yet there were these weird things going on that you couldn't quite figure out it's like what the heck is going on with us right but we teach this all the time in in physics classes right so what was going on well there's just a few there's just a few kind of things things unchecked but basically we're at the end of Discovery because we figured out how everything works because we've got we've got basically Newtonian mechanics and we've got Maxwell's equations which


describe basically how matter gets pushed around and how electromagnetism Works holy cow what a feat there are these few nagging things like for instance there's certain kinds of rocks that for some reason like if you put a photographic plate around it it like it's burned or it gets an image on it like well where's the electromagnetism in that there's no electromagnetic properties of this rock oh yeah and the other thing too is that if I if I take this wonderful classical derivation of how a a something that is hot about how it releases radiation everything looks fantastic perfect match oh until I get to high frequencies


of the light and then it basically just the whole thing falls apart in fact it gives a physical explanation which is total nonsense it tells you that every object should basically be producing an infinite amount of heat and by the way here's the Sun and we can look at the Sun and we can figure out it's made out of hydrogen and Lord Kelvin actually made a very famous you know calculation who was basically one of the founders of thermodynamics so you look at the hydrogen hydrogen has a certain energy content that you know the latent heat basically of hydrogen we know the mass of the sun because we knew the size of it and he conclusively proved that


basically there could only the the sun could only make net energy for about two or three thousand years so therefore all this nonsense about like deep is like because clearly the sun can only last for two or three thousand years if you think about the captain this is basically the chemical energy content of hydrogen and what comes along in one decade basically one guy sitting in a postal office you know in Switzerland figures out that all these you know Einstein of course which was like figured out all this create like took these these seemingly unconnected things and it's like boom there it is this is what it


was interest him but it was like there's quantum physics like this explains this other disaster and then this other guy my hero Ernest Rutherford experimentalist did the most extraordinary experiment which is like which was that okay they had these funny rocks they emitted these particles in fact they called them alpha particles Alpha just a in the alphabet right because it was the first thing that they discovered and what were they doing so they were they were taking these alpha particles and I by the way I do this to all my students because it's a demonstration of what you should be as a good scientist


so he took these Alpha things and he was classically trained physicists knew everything about momentum scattering and so forth like that and he took this and these Alpha which clearly were some kind of energy but they couldn't quite figure out what it was so so let's try to figure that we'll actually use this to try to probe the nature matter so he took this to these alpha particles and a very very thin gold foil and so what you wanted to see was that as they were going through the way that they would scatter based on classical in fact a coulomb collision based on classical mechanics this will tell me reveal something about what the


nature of the charge distribution is in matter because they didn't know like where the hell is this stuff coming from even though they solved that electromagnetism they didn't know like what made up charges okay very interesting on through it goes and so what did you set up so it turns out in the in these experiments what you did was because if these out these so-called Alphas which actually now we know is something else as they go through they would deflect how much they deflect tells you how strong an electric field they saw so you put detectors because if you put if you put like a piece of glass in front of this what


will happen is that when the alpha particle hits it literally gives a little a little bit of light like this it's scintillates a little blue flash so he would train his students or post like whatever the heck they were at the time you have to train yourself because you have to put yourself in the dark for like hours to get your eyes adjusted and then they would start the experiment and they would sit there and literally count the things and they could see this pattern developing which was revealing about what was going on but there was also another part to the experiment which was that it's like here's the alphas here's the


source they're going this way they could tell they were going in One Direction only basically they're going in this direction and you put all these over here because you want to see how they deflect and bend through it but you put a control in the experiment but you basically put glass particle glass glass plates back here because obviously everything should just deflect but nothing should bounce back so it's a controlling experiment but what did they see they saw things bouncing back like what the hell like that fit no model of any idea right but Rutherford like refused to like


ignore what was a clear like they validated it and he sat down and based on classical physics he made the most extraordinary discovery which was the nucleus which is a very very strange Discovery what what I mean by that because what he could figure out from this is that in order for these particles to bounce back and hit this plate they were hitting something that must be heavier than them and that that basically something like 99.999 of the mass of the matter that was in this gold foil was in something that contained about one trillionth of the volume of it and that's called the nucleus


and until and you talk about so how revealing is this is like this totally changes your idea of the universe because a nucleus is a very unintuitive non-intuitive thing it's like why is all the mass in something that is like zero like it basically is the realization that matter is empty it's all empty space and that changes everything and it changes everything until you had that like you had steam engines by the way you had Telegraph wires you had all those things but that that realization like opened up those two realization opened up everything like lasers every all you think about the modern world of what we use


and that set it up so all I would point out is that there's a story already that sometimes there's these nagging things at the edge of science that you know we seem we Pat ourselves on the back and we think we got everything under control and of course that by the way that was the origin of also that that it think about this that was 1908 it took like another 20 some years before people put that together with that's the process that's powering Stars is the rearrangement of those nuclei not atoms that's why Kelvin wasn't wrong he just he was working with the wrong assumptions right so of the fast forward to today like what would this mean right


well there's a couple of things like this that sit out there in physics and I'll point out one of them which is very interesting we don't know what the hell makes up 90 of the mass in the universe so that you know the search for dark matter right what is it we still haven't discovered it yeah ninety percent of the mass of the universe is undetectable like what and then you know then dark energy and again black holes are the the window into this as well then black hole I mean sometimes black holes are way better understood than those things as well too so all it tells us is that we shouldn't have hubris about the ideas that we understand everything and when


we you know who knows what other the next major intellectual Insight will be about how the universe you know functions and actually I think Rutherford is the one who's attributed at least that uh that quote that physics is the only real science everything else is stamp collecting right so uh there's I'm so he's my hero but I'll slightly disagree with that yes well no off has a stamp collected that's very important too but you know that you have to have humility about the kind of disciplines that make progress at every stage in in science in in science yeah that physics did make a huge amount of progress in


the 20th century but it's possible that other disciplines start to step in yeah but Rutherford couldn't imagine like mapping the human genome because we didn't even know about DNA yeah or computers really or computer you really probably didn't think deeply about computation it's like is it here's here's a wild one what if like the next great Revelation to humanity about the universe is not done by the human mind that seems increasingly like more likely and then you start to ask deep questions about what is the purpose of science for example if


um AI system will design a nuclear fusion reactor better than humans do but we don't quite understand how it works and they AI can't we know that it works we can test it very thoroughly but we don't know exactly what the control mechanism is maybe what the chemistry the physics is uh AI can't quite explain it they just can't it's it's impenetrable to our Consciousness basically trying to hold it all together and then and then okay so now we're living in that world where many of the biggest discoveries are made by AI systems yeah uh as if we weren't going big yeah I I say you know it's again another point


out like when my when when my godmother was born like none of this was in front of us right it's like we live in an amazing time it's like right like my grandfather you know plowed you know feels with a horse I get to work on designing Fusion reactors yeah yeah pretty amazing time but still there's humans so we'll see we'll see we'll see if that's around 100 years maybe it'll be yeah I think we're pretty resilient actually yeah no that's that's one lesson from life is it uh finds a way yeah let me ask you in a bigger question if is it as if those weren't big enough let's look out


maybe a few hundred years maybe a few thousand years out there's something called the kardashev scale it's a method of measuring civilization's level of technological advancement based on the amount of energy it's able to use so type 1 civilization and this might be given all your work is not no longer a scale that makes quite make sense but it very much focuses on the source of fusion natural source of fusion which is for us the Sun and type 1 civilizations are able to Leverage uh sort of collect all the energy that hits Earth and then type 2 civilizations are the ones that are able to Leverage


the entirety of the energy that comes from the Sun by maybe building something yeah so when will we reach type 1 status is get to the level which were I think maybe a few orders of magnitude away from currently and in general do you think about this kind of stuff because where energy is so fundamental to this like of life on Earth but also the expansion of life into the universe oh yeah so what one of the fun you know on the on a weekend one I I sat down and figured out what would it mean for Interstellar travel like to have a DT Fusion in fact one of the I talked about my design class one of my design classes was how you use


um essentially a special configuration of a fusion device for not only traveling to but colonizing Mars so because what would you talk about energy use being at the heart of civilizations like so what if you want to go to Mars not to just visit it but actually like leave people there and make it something happen and these massive amounts of energy so what would that look like and it actually transforms what how you're thinking about doing that as well too oh yeah so we we do all those kinds of fun and actually it was a fairly you know quasi-realistic actually so do you think it'll be nuclear fusion that powers the civilization on Mars well what we


considered was something so it turns out that there's thorium which is a heavy element so it's a so-called fertile element that we know what we still know fairly little about the the geology of Mars and in the Deep sense and we know that there's a lot of this on the surface of Mars so one of the things we considered was what would happen that it's basically a combination of a fusion device that actually makes fuel from the thorium oh but the under but the underlying energy one was was Fusion itself as well too so this is one of the examples of being trying to be clever right around those things or what is it you know this


also means it's like an Interstellar travel it's like oh yeah that looks almost like impossible basically from an energy balance point of view it's just because like the energy required to that you have to transport to get there almost the only things that would work are DT fusion and basically um Annihilation It's like Star Trek right absolutely your sense is that Interstellar travel will require fusion power oh it's it's almost even impossible with fusion power actually it's so hard it's so hard because you have to carry the fuel with you and the rocket equation tells you about how much fuel


you use to take so what you end up with is like how long does it take to go to these places and it's like staggering you know periods of time so I I tend to believe that there is alien civilizations dispersed all throughout yeah but we might have totally isolated from them so you think we're not there's none in this galaxy so like and I guess and the question I also have is what kind of do you think they have nuclear fusion I was like is it all yes the physics all the same yeah oh the physics is all the same yeah right so this is the and this is the Fermi Paradox like where where the hell is everybody in the universe right


um well there's some so you know the scariest one of those is that I would point out that there's been you know there's you know order of many tens of millions of species on the planet Earth and only one ever got to the point of sophisticated tool use that we could actually start essentially leveraging the power of what what's in nature to our own will does this mean that basically this means so almost look there is almost certainly life or DNA equivalence or whatever would be somewhere I mean just because you just need to soup and you need energy and you get Organics and whatever the equivalent of amino acids are but you know most of


life on Earth has been that those are still amazing but it's still it's not very interesting are we are we actually the accident of History this is a very interesting one they're super rare super rare and then of course the other part is that also just the other scary part of it which is if you look at the fairy paradoxes good good we got to this point how long has it been in humans so humans Homo Sapien has been around for whatever 100 000 years 200 000 years um our ability in in that timeline to actually make an imprint on the universe like for by emitting radio waves or by modifying you know in nature in a significant way has only been for about


a hundred of those hundred thousand years and you know are we it's a good question so is it by definition that by the fact that when you are able to reach that level of being able to manipulate nature and for example discover you know discover like fission or or or other or or burning fossil fuels and all this is that what it says oh you're doomed because by definition any species that gets to that point that can modify their environment like that they'll actually push themselves you know past that's that's one of the most depressing scenarios that I can imagine yeah so the the so basically


we're we will never line up in time because you get this little teeny window in time over civilization might occur and you you can never see it because you never these these sort of like scatter like like fireflies around the Galaxy and you never yeah yeah and then explodes it destroys itself because of the potential and when we say destroy ourselves all we would have to do is that we basically go if you humans are all left and we're still living on the planet and but all we have to do is go to the technology of like you know 1800 yeah and we're invisible in the universe again yeah he so it was when I when I listened


to the part I I thought I wanted to talk about this as well too because this it comes from well it comes from a science point of view actually of what it means but also to me it's like another compelling driver of telling us it's like why we should try really hard not to screw this up like we're in this unique place of our ability to discover and make it and I just don't want to give up about thinking that we can get through yeah I tend to see that there is some kind of game theoretic Force like with Demetrius shared destruction that ultimately in each human being there's a desire to survive and a willingness to cooperate to have compassion for each


other in order to survive and I think that I mean maybe not in humans but I can imagine nearly infinite number of species in which that overpowers any uh technological advancement that can destroy or rewind the species so I think if humans fail I hope they don't I see a lot of evidence for them not but it seems like somebody will survive and there you start to ask questions about why why we haven't met yet maybe it's just space is large oh spaces it's I I think in logarithms and I can't even fathom you know space this is extraordinary right yeah it's


extraordinarily large yeah I mean there's so many places on Earth I just recently visited Paris for the first time yeah and there's so many other places I haven't visited there's so many other places well I like to you know it's interesting that we have this fascination with alien life we have what is essentially alien life on Earth already like you think about the organisms that develop around deep sea like thermal vents one of my favorite books of all time from Stephen J Gould if you've never read that book it kind of blows your mind it's about the Cambrian explosion of life and it's like oh you look at these things and it's


like our the chance of us existing as a species like the the genetic diverse city was larger back then you know this is about five about 500 million years ago or something like that it is a mind-altering trip of thinking about our place in the universe I have to say plus the Mind itself yeah is the kind of alien but almost um almost a mystery to ourselves we still don't understand it the very the very mechanism that helps us explore the world is still a mystery yeah so that like understanding that will also unlock um a quite quite possibly unlock our ability to understand the world and


maybe build machines that help us entertain the world build tools then I mean it already has I mean our ability to understand the world is is ridiculous almost Ashley [Laughter] so what uh advice would you give to uh young folks or folks of all ages or lost in this world looking for a way looking for a career they can be proud of or looking to have a life they can be proud of yeah oh the first thing I would say is don't give up I get to see uh multiple sides of this and you know there's there seems to be um a level of Despair in a Young Generation it's like you know it's it's


almost like the Monty Python skit like I'm Not Dead Yet right I mean yeah like we're we're not there we're we're in a place that you know in in you know you know don't say the world's going to end in 300 days or something it's not okay and when we mean by this is that we have a robust Society that's figured out how to do like amazing things and we're gonna keep doing amazing things but that shouldn't be complacency about what our future is and the future for their children as well too and in the end I mean it's a very it's a staggering Legacy to think of what we've built up primarily by basically using carbon fuels like people almost tend to


think of this as an evil thing that we've done I think it's an amazing thing that we've done but we owe it to ourselves and um and and to this thing that we've built let me talk about the end of the world is this nonsense what it is is it's the end of this kind of lifestyle and civilization at this scale and the ability to execute on these kinds of things that we were talking about today like we are extraordinarily privileged we are in a place where it's just it's it's almost unfathomable compared to most of the the misery that humans have lived in for our history so don't give up about this okay but also roll up your sleeves and let's get going


at solving and getting real solutions to the problems that are in front of us which are significant you know it's I would most of them are linked to how what we use in energy but it's not just that it's it's around all the aspects of like what does it mean like what does it mean to have a distributed energy source that lifts billions of people out of poverty you know particularly outside of like the Western Nations right that seems to me a pretty compelling you know moral goal for our for all of us um but particularly for this upcoming you know uh generation and then the other part is that is that we've got


possible solutions in front of us apply your talents in a way that that that you're passionate about and is going to make a difference and that's only possible with the optimism hope and hard work yeah what uh easy question certainly easier than nuclear fusion what's the meaning of life why are we here 42 is it 42 no no um we already discussed about the beauty of physics that there's almost a desire to ask a why question about why the parameters have these values yeah it's very tempting yeah it's it's an interesting hole to go down as a scientist because


we're a part of what people have a hard time people who aren't scientists have a hard time understanding what scientists do to themselves and a great scientist does a very non-intuitive or non-human thing what we do is we train ourselves to doubt ourselves like hell like that's a great scientist we doubt everything we see we doubt everything that we think because we we try to we we basically try to turn off the belief valve right that humans just naturally have um so when it comes to these things like I can I can make my own comments to this is like personally you see these things about the ratios of life and I made a comment where I said well you know a


wrap my some part of my brain that just goes Yeah well yeah because we're the only interesting you know Multiverse because by definition it has to look like this you know but there's I have to say there's other times I can say in the history of the whole of what has happened over the last 10 years there have been some pretty weird coincidences like coincidences that like you look at it and just go is that really was that really a coincidence is something like pushing us toward towards these things and it's a natural it's a human instinct because you know since the beginnings of humanity we've


always assigned you know you know human motivation and and and needs to these somewhat you know empirical observations and in some sense the stories before we understand the real explanations the stories the myths uh Service as a as a good approximation yeah for the thing that we're yet to understand absolutely and in that sense you said the antithesis to sort of scientific doubt is is having a faith in these stories they're almost silly when uh looked at from a scientific perspective but just even the feelings of it seems that love is a fundamental fabric of human uh condition and what the hell is that


as the physicist I go it's you know this is this is a repeatable thing that's due to a set of synapses that fire in a particular pattern and all this yes you know that's kind of like okay man what a you know what a drag that is right to think of it this way and you can have an evolutionary biology explanation but there's still a magic to it I mean I see scientists I have some of my colleagues you know do this as well too like where what what is spirituality compared to science and so forth I my own my own feeling in this is that you know as a scientist because I've had the pleasure of being able to like both understand what my predecessors did but


I also had the privilege of being able to discover things right as a scientist and and I see that and you just in just in just the range of our conversations like that is my in a weird way my it's the awe that comes from looking at that that is if you're not in awe of the universe and nature you haven't been paying attention I mean my own personal feeling is that I feel uh if I go if I go snorkeling on a coral reef I feel more awe than I could ever feel like in a in a church you kind of notice some kind of magic there there's something about the way the whole darn thing holds together that just sort of


escapes your imagination and that's to me the this thing of and then we have different words we call them holistic or spiritual the way that it all hangs together in fact one of the interesting things you asked about like what I think about well the craziest things that I think that how does it hold together is like our society like how does oh look what yeah like how because there's no way like you just think of the United States there's 330 million people kind of working like this engine about going towards making all these things happen but there's like no one in charge of this really not really yeah how the how the heck does this happen it's kind of


like it's so the these things these are the kinds of things mathematics automatically and organization wise that I think of just because they're they're sort of they're awe-inspiring and there's different ideas that would come up together we share them and then there's uh there's teams of people that share different ideas and those ideas compete like there's the ideas themselves are these kinds of different organisms and ultimately somehow we build Bridges and and nuclear reactors and do those things well I have to give a shout out to my daughter by the way who's who's interested she's an applied math major


and she's she's amazing at math and over the break she was showing she's doing researches it's basically about how ideas and Ethos are transmitted within a society nice so she's building an applied math model who's explaining like she was showing me on this like the simulation she goes oh look look at this and I said oh oh that's like how political parties like evolve right yeah and even though it was a rather you know quote-unquote simple math mathematical model it wasn't really it's like oh wow well maybe she has a chance to derive mathematically the the answer to the what's the meaning of life there we go and maybe it is indeed 42. well


um Dennis thank you so much for just doing creating tools creating systems exploring this idea that's one of the most amazing magical ideas in all of uh human endeavor which is nuclear fusion I mean that's so interesting you know it's almost like my one of my lifelong goals is like to make it it's like it's not magic it's like it's as boring as all heck and this means we're using it everywhere right yeah yeah and the magic is then built on top of it yeah well thank you for everything you do uh thank you for talking to me it's a huge honor this is a fascinating and amazing conversation

Key Themes, Chapters & Summary

Key Themes

  • Fundamentals of Nuclear Fusion

  • The Role of the Sun in Fusion

  • High-Temperature Requirements for Fusion

  • Plasma: The Fourth State of Matter

  • Quantum Tunneling in Fusion

  • Challenges in Fusion Technology

  • Magnetic vs. Inertial Confinement Methods

  • Nuclear Fission vs. Fusion

  • Safety and Weaponization Concerns

  • Societal and Environmental Implications of Fusion


  • Introduction to Nuclear Fusion

  • Understanding the Sun's Fusion Process

  • Achieving Fusion: The Heat Challenge

  • Exploring Plasma Dynamics

  • Quantum Mechanics in Fusion

  • Overcoming Fusion's Technical Hurdles

  • Comparison of Fusion Confinement Techniques

  • Distinguishing Fusion from Fission

  • Safety Aspects and Nuclear Concerns

  • Fusion's Impact on Society and Environment

  • Conclusion: The Future of Fusion Energy


Dennis Whyte, a nuclear physicist and director of the MIT Plasma Science and Fusion Center, delves into the intricacies of nuclear fusion during a conversation on the Lex Fridman Podcast. Fusion, a fundamental process powering the universe, involves merging lighter elements into heavier ones, releasing substantial energy. This process, epitomized in stars like our sun, essentially converts hydrogen into helium, a highly stable element due to its nuclear structure. The conversation highlights the sun's role as a colossal conversion engine, transforming hydrogen into helium, thereby sustaining life.

Whyte explains that for fusion to occur, extremely high temperatures are necessary to overcome the repulsive forces between positively charged particles. In the sun's core, temperatures reach about 20 million degrees Celsius. On Earth, achieving fusion requires temperatures around 50 million degrees Celsius. This high-energy state creates plasma, the fourth state of matter, prevalent throughout the universe. Plasma's unique behavior, unlike gases, liquids, or solids, stems from its charged particles interacting over distances, leading to diverse and complex dynamics.

The discussion touches on the concept of Quantum tunneling, a critical phenomenon allowing particles in fusion to overcome energy barriers. In this process, particles behave as waves, enabling fusion reactions even at temperatures where classical physics would deem them improbable. This quantum effect is essential for the operation of stars and potential Earth-based fusion reactors.

Fusion technology, while promising, faces significant challenges. These include achieving and maintaining the necessary high temperatures, confining the plasma effectively, and ensuring a sufficient density of fusion fuel. The conversation then shifts to discuss various fusion methods, including magnetic and inertial confinement, each with its unique requirements and challenges.

Whyte also contrasts fusion with fission, the process used in nuclear weapons and current nuclear power plants. Fission, involving the splitting of heavy, unstable elements like uranium, is fundamentally different from fusion and has distinct implications, especially in terms of safety and weaponization.

The talk further explores the broader implications of fusion technology. Whyte contemplates how fusion, as a clean, safe, and potentially cheap energy source, could revolutionize energy use and impact global geopolitics, wealth distribution, and environmental sustainability. Fusion's development, while not immediate, promises a transformative shift in how humanity harnesses and uses energy.