伊恩·哈欽森：核聚變、等離子體物理與宗教

The following is a conversation with Ian Hutchinson, a nuclear engineer and plasma physicist at MIT. He has made a number of important contributions in plasma physics, including the magnetic confinement of plasmas, seeking to enable fusion reactions, which happens to be the energy source of the stars, to be used for practical energy production. Current nuclear reactors, by the way, are based on fission, as we discuss. Ian has also written on the philosophy of science and the relationship between science and religion, arguing in particular against scientism, which is a negative description of the overreach of the scientific method to questions not amenable to it. On this latter topic, I recommend two of his books, his new one, Can a Scientist Believe in Miracles?, where he answers more than 200 questions on all aspects of God and science, and his earlier book on scientism called Monopolizing Knowledge. As you may have seen already, I work hard on having an open mind, always questioning my assumptions, and in general marvel at the immense mystery of everything around us and the limitations of at least my mind. I'm not religious myself in that I don't go to the synagogue, a church, a mosque, but I see the beautiful bond in the community that religion at its best can create. I also see, both in scientist and religious leaders, signs of arrogance, hypocrisy, greed, and a will to power. We're human. Whether Buddhist, Christian, Hindu, Jewish, Muslim, agnostic, or atheist, this podcast is my humble attempt to explore a complicated human nature. What Stanislav Lem in his book Solaris called our own labyrinth of dark passages and secret chambers. I ask that you try to keep an open mind as well and be patient with the limitations of mind. Quick summary of the ads. Two new amazing sponsors, Sunbasket and Powerdot. 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They told me to say right now, with urgency, so pause this podcast and go to the website and make the purchase, or just go to the website and check it out. And enter a promo code LEX at checkout. This show is also sponsored by Power Dot. Get it at powerdot.com slash lex and use code LEX at checkout to get 20% off and to support this podcast. This thing is amazing. It's an eStim electrical stimulation device that I've been using a lot for muscle recovery recently, mostly for my shoulders and legs as I've been doing the 1000 bodyweight reps and 6 miles every day as I just finished. They call it the smart muscle stimulator, which is true, since the app that goes with it is amazing. It has 15 programs for different body parts and guides you through everything you need to do. I take recovery really seriously these days and Power Dot has been a powerful addition to the whole regime of stretching, ice, massage, and sleep and diet that I do. It's used by professional athletes and by slightly insane but mostly normal people like me. It's portable so you can throw it in a bag and bring it anywhere. Get it at powerdot.com slash lex and use code LEX at checkout to get 20% off on top of the 30 day free trial and to support this podcast. And now here's my conversation with Ian Hutchinson. Maybe it'd be nice to draw a distinction between nuclear physics and plasma physics. What is the distinction? Nuclear physics is about the physics of the nucleus. And my department, Department of Nuclear Science and Engineering at MIT, is very concerned about all the interactions and reactions and consequences of things that go on in the nucleus, including nuclear energy, fission energy, which is the nuclear energy that we have already, and fusion energy, which is the energy source of the sun and stars, which we don't quite know how to turn into practical energy for humankind at the moment. That's what my research has mostly been aimed at. But plasmas are essentially the fourth state of matter. So if you think about solid, liquid, gas, plasma is the fourth of those states of matter. And it's actually the state of matter which one reaches if one raises the temperature. So cold things, you know, like ice are solid. Liquids are hotter water. And if you heat water beyond 100 degrees Celsius, it becomes gas. Well, that's true of most substances. And plasma is a state of matter in which the electrons are unbound from the nuclei. So they become separate from the nuclei and can move separately. So we have positively charged nuclei and we have negatively charged electrons. The net is still electrically neutral. But a plasma conducts electricity, has all sorts of important properties that are associated with that separation. And that's what plasmas are all about. And the reason why my department is interested in plasma physics very strongly is because most things, well, for one thing, most things in the universe are plasma. The vast majority of matter in the universe is plasma. But most particularly, stars and the sun are plasmas because they're very hot. And it's only in very hot states that nuclear fusion reactions take place. And we want to understand how to implement those kind of phenomena on Earth. Maybe another distinction we want to try to get at is the difference between fission and fusion. So you mentioned fusion is the kind of reaction happening in the sun. So what's fission and what's fusion? Well, fission is taking heavy elements like uranium and breaking them up. And it turns out that that process of breaking up heavy elements releases energy. What does it mean to be a heavy element? It means that there are many nuclear particles in the nucleus itself, neutrons and protons in the nucleus itself so that in the case of uranium, there are 92 protons in each nucleus and even more neutrons so that the total number of nucleons in the nucleus, nucleons is short for either a proton or a neutron, the total number might be 235, that's U235, or it might be 238, that's U238. So those are heavy elements. Light elements, by contrast, have very few nucleons, protons or neutrons in the nucleus. Hydrogen is the lightest nucleus. It has one proton. There are actually slightly heavier forms of hydrogen, isotopes. Deuterium has a proton and a neutron and tritium has a proton and two neutrons. So it has a total of three nucleons in the nucleus. While taking light elements like isotopes of hydrogen and not breaking them up but actually fusing them together, reacting them together to produce heavier elements, typically helium, which is helium is a nucleus which has two protons and two neutrons, that also releases energy and that or reactions like that, making heavier elements from lighter elements is what mostly powers the sun and stars. Both fusion and fission release approximately a million times more energy per unit mass than chemical reactions. So a chemical reaction means take hydrogen, take oxygen, react them together, let's say, and get water, that releases energy. The energy released in a chemical reaction like that or the burning of coal or on oil or whatever else is about a million times less per unit mass than what is released in nuclear reactions. So but it's hard to do. It requires very high energy of impact. And actually, it's very easy to understand why. And that is that those two nuclei, if they're both, let's say, hydrogen nuclei, one is, let's say, deuterium and the other is, let's say, tritium, they're both electrically charged. And they're positively charged, so they like charges repel. Everyone knows that, right? So basically, to get them close enough together to react, you have to overcome the repulsion, the electric repulsion of the two nuclei from one another. And you have to get them extremely close to one another in order for the nuclear forces to overtake the electrical forces and actually form a new nucleus. And so one requires very high energies of impact in order for reactions to take place. And those high energies of impact correspond to very high temperatures of random motion. So that's why you can do something like that in the sun. So we can build the sun. That's one way to do it. But on Earth, how do you create a fusion reaction? Yeah. Well, nature's. Engineering wise. Nature's fusion reactors are indeed the stars, and they are very hot in the center. And they reach the point where they release more energy from those reactions than they lose by radiation and transport to the surface and so forth. And that's a state of ignition. And that's what we have to achieve to give net energy. That's like lighting a fire. If you have a bundle of sticks and you hold a match up to it and you see smoke coming from the sticks, but you take the match away and the sticks just fizzle out. That's not the reason they fizzled out is that, yes, they were burning, there was smoke coming from them, but they were not ignited. But if you are able to take the match away and they keep burning and they are generating enough heat to keep themselves hot and hence keep the reactions going, that's chemical ignition. But what we need to do, what the stars do in order to generate nuclear fusion energy is they are ignited. They are generated enough energy to keep themselves hot. And that's what we've got to do on Earth if we're going to make fusion work on Earth. But it's much harder to do on Earth than it is in a star because we need temperatures of order tens of millions of degrees Celsius in order for the reactions to go fast enough to generate enough energy to keep it going. And so if you've got something that's tens of millions of degrees Celsius and you want to keep it all together and keep the heat in long enough to have enough reactions taking place, you can't just put it in a bottle, plastic or glass, it would be gone in milliseconds. So you have to have some nonmaterial mechanism of confining the plasma. In the case of stars, that nonmaterial force is gravity. So gravity is what holds the star together, it's what holds the plasma in long enough for it to react and sustain itself by the fusion reactions. But on Earth, gravity is extremely weak. I mean, I don't mean to say we don't fall, yes, we fall. But the mutual gravitational attraction of small objects is very weak compared with the electrical repulsion or any other force that you can think about on Earth. And so we need a stronger force to keep the plasma together, to confine it. And the predominant attempt at making fusion work on Earth is to use magnetic fields to confine the plasma. And that's what I've worked on for much, essentially most of my career, is to understand how we can and how best we can confine these incredibly hot gases, plasmas, using magnetic fields with the ultimate objective of releasing fusion energy on Earth and generating electricity with it and powering our society with it. A dumb question. So on top of the magnetic fields, do you also need the plastic water bottle walls or is it purely magnetic fields? Well, actually what we do need walls, those walls must be kept away from the plasma because otherwise they'd be melted or the plasma must be kept away from them inside of them. But the main purpose of the walls is not to keep the plasma in, it's to keep the atmosphere out. So if we want to do it on Earth where there's air, we want the plasma to consist of hydrogen isotopes or other things, the things we're trying to react. And by the way, the density of those plasmas, at least in magnetic confinement fusion, is very low. It's maybe a million times less than the density of air in this room. So in order for a fusion reactor like that to work, you have to keep all of the air out and just keep the plasma in. So yes, there are other things, but those are things that are relatively easy. I mean, making a vacuum these days is technologically quite straightforward. We know how to do that. What we don't quite know how to do is to make a confinement device that isolates the plasma well enough so that it's able to keep itself burning with its own reaction. So maybe can you talk about what a tokamak is? The Russian acronym from which the word tokamak is built just means toroidal magnetic chamber. So it's a toroidal chamber, a torus is a geometric shape which is like a doughnut with a hole down the middle. And so it's the meat of the doughnut, that's the torus, and it's got a magnetic field. So that's really all tokamak means. But the particular configuration that is very widespread and is the sort of best prospect in the least in the near term for making fusion energy work is one in which there's a very strong magnetic field the long way around the doughnut, around the torus. So you've got to imagine that there's this doughnut shape with an embedded magnetic field just going round and round the long way. The big advantage of that is that plasma particles when they're in the presence of a magnetic field feel strong forces from the magnetic field and those forces make the particles gyrate around the direction of the magnetic field line. So basically the particles follow helical orbits following like a spring that's directed along the magnetic field. Well if you make the magnetic field go inside this toroidal chamber and just simply go round and round the chamber then because of this helical orbit the particles can't move fast across the magnetic field but they can move very quickly along the magnetic field. And if you have a magnetic field that doesn't leave the chamber it doesn't matter if they move along the magnetic field it doesn't mean they're going to exit the chamber. But if you just had a straight magnetic field for example coming from a Helmholtz coil or a bar magnet then you'd have to have ends that would come to the ends of the chamber somewhere and the particles would hit the ends and they would lose their energy. So that's why it's toroidal and that's why we have a strong magnetic field. It's providing a confinement against motion in the in the direction that would lead the particles to leave the chamber. It turns out that here we're getting a little bit technical but turns out that a toroidal field alone is not enough and so you need more fields to produce true true confinement of plasma and we get those by passing a current as well through the plasma itself. I can make sure it stays on track. Well that what that does is makes the field lines themselves into much bigger helices and that for reasons that are too complicated to explain that clinches the confinement of the particles at least in terms of their single particle orbits so they don't leave the chamber. So when the particles are flying along this this this donut the inside of the donut are through Jesus there was a that's kind of a historical moment that's profound that's really powerful do you also think that God makes himself seen in less obvious ways in our world today absolutely absolutely I mean it's it's certainly been the outlook of Jews and Christians throughout history that God is seen in the creation that we when we look at the creation we see to some extent the wonder the majesty the might of the person or the entity but the person who created it and and that's a way in which scientists particularly have over over the ages and certainly over most of the last five centuries since the scientific revolution scientists have seen in a certain sense the hand of God in creation I mean this leads us perhaps to a different discussion but I mean it's it's remarkable to me how influential Christianity and religion in generally has been in science yeah most of the scientists through history as if you described I mean God has been a very big part of their life and their work certainly up until the at the beginning of the 20th century that was the case so maybe this is a good time to can you tell me what scientism is yeah I mean the short answer is that by scientism we mean we mean the belief that science is all the real knowledge there is that's a shorthand there are lots of different facets of it and what which one can explore and the book in which I explored it most most thoroughly was actually an earlier book called monopolizing knowledge and and the purpose of that title is to is to draw attention to the fact that in our society as a whole in particularly in the West today we we have grown so reliant on science that we that we tend to put aside other ways of getting to know things and so of course at MIT we are focused on science and we do focus on it very much but the truth is that there are many ways of getting to know things in our world know things reliably in our world and a lot of them are not science so scientism in my view is a terrible intellectual error it's to believe it's the belief that somehow the methods of science as we develop them with you know experiments and in the end they it relies particularly upon reproducibility in the world and on a kind of clarity that comes from measurements and mathematics and related types of of skills those powerful though they are for finding out about the world are not all the knowledge do not give us all the knowledge we we have and there's many other forms of knowledge and the illustration that I usually use to to try to help people to think about this is to say well look let's think about human history I mean to what extent can human history be discovered scientifically the answer is essentially can't because and the reason is because human history is not reproducible you can't do reproducible experiments or observations and and go back and you know try it over again it's it's a one off thing you know the history is full of unique events and and so you you know you you can't hope to do history using the methods of science yeah I mean in some sense history is a story of miracles I mean they don't have to do with God it's just uniqueness is anyway unique events unique events and that science doesn't like that because it's unique events by their very definition are not reproducible can I ask sort of a tricky question I don't even know what atheist or atheism is but is it possible for somebody to be an atheist and avoid slipping into scientism oh yeah absolutely I mean it I mean there these are two separate things okay I'm quite sure there are many people who don't believe in God and yet recognize that there are many different ways of we get knowledge you know some is history some is sociology economics politics philosophy art history language literature etc etc there are many people who recognize those disciplines as having their own approaches to epistemology and to get how we get knowledge and valuing them very highly I don't mean to say that everyone you know who's an atheist automatically you know subscribes to the scientistic viewpoint that's not true but it's certainly the case that many of the arguments in fact most of the arguments of the aggressive atheists of this century people are sometimes called new atheists although they're actually rather old most of their arguments are rather old you know are drawing heavily on scientism so when they say things like there's no evidence to support Christianity okay what they are really focusing on is to say is saying that Christianity isn't proved or the evidence for Christianity is not science okay science doesn't prove it and and you you know if you read their books that's what you find they really mean is science doesn't lead you necessarily to believe in a creator God or into it in any particular in religion I accept that that's not a problem to me because I don't think that science is all the knowledge there is and I think there are other important ways of getting to know things and one of them is historical for example and I mentioned earlier that I think I became persuaded and I were and I still am persuaded that the historical evidence for the resurrection is very is very persuasive again it's not proof or anything like that but it's but it's pretty good evidence okay yeah I've um I talked to Richard Dawkins on this podcast and um uh and uh I saw you debate with Sean Carroll so I I understand this world it makes it makes me very curious maybe uh let me ask sort of another way my own kind of uh world view maybe you can help as by way of therapy understand um you know because you've kind of said that there's other ways of knowing what about if we if if I kind of sit here and am cognizant of the fact that I almost don't know anything so sort of I'm sitting here almost paralyzed by the the mystery of it all and it's not even when you say there's other ways of knowing it um it feels almost too confident to me because uh yeah when I when I listen to beautiful music or uh see art there's something there that's and that's uh that's beyond the reach of scientism I would say so beyond the reach of uh the the tools of science but I don't even feel like that could be as an actual tool of knowing it um yeah I just don't even know where to begin because it just feels like we know so little like uh if we look even a hundred years from now when people look back to this time humans look back to this time they'll probably laugh at how little we knew even a hundred years from now and if we look at a thousand years from now hopefully we're still alive or some version of ourselves or AI version of ourselves you know they they'll certainly laugh at the absurdity of our beliefs so what do you uh so you don't seem to be as paralyzed by how little we know you confidently push on forward but what do you make of that sense of uh of just not knowing of the mystery we need to be modest or or humble if even about what we know I accept that and I certainly think that's true not not simply because in the future we'll know more science and and there will be more powerful ways of finding out about things but simply because you know sometimes we're not right we're wrong okay in what we think we know um uh so that's crucial but it's also a very Christian outlook that kind of humility is what Jesus taught so I so I don't know whether this was in the back of your mind when you were thinking about this but it's often the case that um people of religious faith are are accused of being dogmatists okay and there is a sense in which dogma teaching accepted teaching is is part of religions okay but I don't think that necessarily uh uh that leads one to blind dogmatism and I don't I certainly don't think that faith we can talk about this later if you'd like but I certainly don't think that faith means thinking you know something and not listening to counter arguments for example um so I I think that's crucial yeah what is uh what does faith mean to you what does it uh feel like what does it actually sort of how do you carry your faith in terms of the way you see the world well I think faith is very often misunderstood in our society at the moment um because uh it's often portrayed as being nothing other than uh believing things you know ain't true you know um or or believing things that are are are not proven okay um and um and this and faith does have a strand which is to do with you know basically believing in um in concepts or um propositions but actually the the word faith is much broader than that faith also means um you know trusting in something trusting in a person or trusting in a thing uh the reliability of some technology for example um that's equally part of the meaning of the word faith and and there's a third strand to the to the meaning of the word as well and that is loyalty um so you know I have faith in my wife and and I try to act in faith towards her and that's a kind of loyalty and so those three strands are the are the most important strands of the meaning of faith yes belief in uh in propositions that we might not have you know full proof about or maybe we have very little proof about but it's also trust and and loyalty and actually in the in terms of the Christian faith Christians are far more called to trust and loyalty than they are to belief in things they don't you know don't have proof of okay um but but the critics of religion generally um tend to emphasize the first one and say well you know you believe things for which you have no evidence okay that's what that's what they think faith is well yeah there there is a sense in which everybody has to live their lives uh believing or or or making decisions in situations when they don't have all the proof or evidence or knowledge that enables you to make a completely um rational or well informed or prudent decision we you know we do this all the time you know my drive down here I nearly took a wrong turning and I thought which which which way do I go do I keep going straight on and so my uh voice came out and I think go straight okay so so you have to make decisions and sometimes you know you don't have a navigation system telling you what to do you just have to make that decision with no with insufficient evidence and you're doing it all the time as a human and that's part of being sentient um and so that kind of um action and belief on the basis of incomplete evidence is not something that I feel uncomfortable doing or I feel that I feel that somehow my Christian commitments are forced me to do when I wouldn't have had to have done it otherwise I would have had to do it anyway um and and so you know there's a sense in which um I think it's important to see the breadth of meaning of faith and and and to recognize that in certainly in the case of Christianity um it's trust and loyalty that the the key themes that we're called to and I mean another interesting extension of that that you speak to is kind of loyalty is referring to a connection with something outside of yourself yeah um so I think you've spoken about like existentialism or even just atheism in general as um as leading naturally to an individualism as a focus on the on the self and uh ideas that maybe the Christian faith can um instill in you is um allowing you to sort of look outside of yourself so connection I mean loyalty fundamentally is about other beings um and yeah other beings and I mean I think I don't know what it is in me but I'm very much drawn to that idea and um I think humans in general are drawn to that idea you can you can make all kinds of evolutionary arguments all that kind of stuff but uh people always kind of tease me uh because I talk about love a lot and I mean there's a lot of uh non scientific things about love right like what the heck is that thing why why do we even need that thing it uh it seems to be an annoying burden that uh that we we get so much uh joy in in life from a connection with other human beings deep uh lasting connections with human beings same thing with loyalty why why do we get so much value and pleasure and strength and meaning from loyalty from a connection with somebody else uh going through uh thick and thin with somebody else going through some hard times I mean some of the you know the closest friends I I have is going through some some rough times together and that seems to make life deeply meaningful what is that so yeah um I that's that resonates with me and I obviously I would I would affirm it um I think just to just to correct the implication that you made I I don't think it's necessarily the the consequence of atheism uh that we that we lose track of those kinds of things I I mean I think that atheists can be loyal okay if you like um the question more often comes up in the context of you know where does morality come from and loyalty I think and duty are related to one another you know if we have loyalty to someone then we have a duty to them okay as well and I think that insofar as we see ourselves as having some kinds any kinds of duties or moral compulsions with respect to our relationships to other people it's I think it's a question that always arises well where does these where do these come from and there there are various approaches that people have towards deciding what makes ethics or or morality moral okay but I do think it's the case that um it's very hard to ground morality um in a in any kind of absolute way or a persuasive way um in mere human relationships and so it's certainly the case that in Christianity um there is a sense in which um morality and you know the morality of morals comes from a transcendent place from a transcendent deity and that we um that we ground are the compelling force of of morals on God are more than we do on individuals because after all you know if it if you if you've got nothing but you know other people why should you you know treat your neighbor well why shouldn't you defraud your neighbor if it's good for you well you know you can construct all kinds of arguments and some of them are you know obviously arguments that are commonplace in religion too you should do as you would be done by and all this kind of thing right but none of that seems any any more than mere pragmatism to most people okay and so that's what that's one of the things if that Nietzsche amongst others you know really identified you know if God is dead if the idea of God is grounding our moral behavior is no longer viable in the West which Nietzsche thought that it wasn't okay then what does ground it and he had no good answer for it in fact he claimed there was no answer but then he couldn't live with that and so he invented the idea of the ubermensch you know this this superior human being okay and this was a different way of trying to ground morality not a very successful one you know you could argue that it's a forerunner of the sort of racism of Hitler's regime and so forth that you know we've in the West thankfully shied away from in the in the past half or three quarters of a century but you know I think it is the case that Christianity gives me a basis for my moral beliefs that is more than mere pragmatism yeah but there is a stepping outside of all that there does seem to be a powerful stabilizing like we humans are able to hold ideas together like in a distributed way outside of whether God exists or not or any that just our ability to kind of converge together towards a set of beliefs into sometimes into tribes it's kind of I don't know if it's inherent to being human beings I hope not because now if I look on Twitter and there's a there's the red team and the blue team right it's almost like it's a care it's some kind of TV show that we're living in that people get into these tribes and they hold a set of beliefs that sometimes don't I mean they are beliefs for the sake of holding those beliefs and we get this intimate connection between each other for sharing those beliefs and we spoke to the things about loyalty and love and that's the thing that people feel inside the tribe and it seems very human that within that tribe those beliefs don't necessarily always have to be connected to anything it's just the fact that you know I've did sports my whole life whenever you're on a team the bond you get with it with other people on the team is incredible and the actual sport is often the silliest I mean I don't play ball sports anymore but the ball when I played like soccer or tennis I mean all those sports are silly right you're playing with a little ball but there's the bond you get is so deeply meaningful I just it's interesting to me on the sociological level that it's possible to me whatever the beliefs of religion is whatever they're actually grounded in they might be they might have a power in themselves I think there is tribalism everywhere and I think tribalism in the US at the moment is rather difficult to bear from my point of view and it's I think fed by the internet and social media and so forth but it's but historically tribalism has been a trait and remains a trait in humans the genius of Christianity is that it supersedes tribalism I mean yes when the Hebrews thought about Yahweh initially they thought about him as their tribal deity just like the tribal deities round about about them and so but and and yet from you know early on in Hebrew history the crucial thing that Yahweh came to mean or I would say revealed of himself to them was that he wasn't just a tribal deity he was the God that created the whole thing and if he is the God of the whole thing then he's not just the God of the Hebrews or in the case of you know Americans God is not just the God of Americans he's the God of everybody okay and that is a way in a way the most amazing transcending of tribal loyalties and one of the crucial you know occasions in the New Testament you know when the Holy Spirit comes at Pentecost you know the the apostles and the and the disciples speak in other tongues and there are people from all all the countries you know round about hear them in their own languages and so you know whether whether you take that as factual or not that is the a statement of the transcendent aspects of Christianity or the claimed transcendent aspects of Christianity that it transcends culture and that's certainly something which I find appealing. When I kind of touch on this topic in my own mind one of the hardest questions is as why is there suffering in the world do you have a good answer well I have I have some answers but you're right that it is one of the toughest questions the problem of pain or the problem of suffering or the problem of theodicy as as theologians call it is is is probably one of the toughest I think it's important to say that there are certain types of answers to this question but there are aspects of this question to which there is no intellectual answer that is going to satisfy and and the fact of the matter is you know when I'm speaking to an audience let's say at at at some kind of lecture I can be sure that there are people in that audience who are either personally suffering they've got illness they've got pains there maybe they're facing death or someone in their family is in similar sorts of situations so suffering is a reality and and there is nothing that I can say that is going to solve their feeling of agony and angst and and maybe despair in those types of situations there is really only one thing that I think humans can do for one another in those kinds of situations and that is simply to be there to be there alongside your friend or your or your colleague or or whoever you know family member or whoever it might be and that's the only really sense in which we can give comfort if we try to give intellectual solutions to these problems we're going to be like like the comforters that were in the book of Job in the in the Bible who who brought no comfort to Job himself with their intellectual answers but if they had been there and some of them were there they sat alongside that is some level of comfort and and after all that's the meaning of the word compassion it means to suffer alongside of somebody and I would say first off you know what does a Christian say about suffering the the first thing a Christian should say is compassion is all that really counts and what's more we say that God has acted in compassion towards us that is to say he has suffered with us in the person of Jesus Christ and when we see the passion of Jesus we recognize that God takes suffering deadly seriously has taken it so seriously that he's been willing to come and be a part of his creation in the person of of Jesus Christ and suffer death the most horrible death on the cross and for our benefit so that's one side of of suffering but the question you know the philosophical question remains you know surely if God is good you know and God is omnipotent benevolent you know why doesn't he take away all the suffering why doesn't he cause miracles to occur that will take away all this suffering I think there are some good answers to that question in the in the following sense that you know we live in a world where the consistency of the world is an absolutely crucial part of it you know the fact that our world behaves reproducibly in the main is absolutely essential for the integrity of our lives without it we wouldn't exist okay and so there is a sense in which the integrity of creation calls for there being consistent behavior which you know these days we think of as being the laws of nature okay and so the consistent behavior of nature is very very important it's what enables us to be what we are and if you're calling upon God in in in in your critique of why isn't this benevolent creator you know fixing things one answer is he's fixed things in a certain sense to have an integrity in them and that integrity is the best thing it's the way we have our existence it's the way we live and move and have our being and you know if you want something different you've got to show that there is a way in which you could invent a world that is better that it has the integrity that we need to exist okay and and and to be able to think and and and love and and be but but you were going to do it better you know and the atheists think that maybe they have got a better idea but if they thought about it a bit more carefully they'd realize no one has put forward a better idea okay so the so another way to say that uh i mean is that suffering is an integral part of this of um of a consistent existence so so sort of uh and the philosophical in a philosophical sense uh the full richness and the beauty of our experience would not be as beautiful would not be as rich uh if there was no suffering in the world is that is that possible well i think you said two different things that aren't exactly at least that aren't exactly the same one is that suffering is an integral part of our experience you know that might be considered a challenge to certain types of christian theology or or even uh jewish theology in other words um christians talk about the fall and talk about uh adam and eve in the garden and and have have a vision of there being some kind of perception from or perfection from which we have fallen and i think there is a perfection from which we've fallen but i don't think that perfection is some kind of physical perfection in other words i don't subscribe personally to the view that some some christians do that there was some state um prior to the fall in which death did not occur i don't think that that's consistent with science as we know it and i and i think that um death for example has been part of the biological world and the and the universe as a whole um from from billions of years ago so so just to be clear about that um you know i on the other hand i do so if that's the case then certainly in that sense at the very least um suffering or at least death okay is part of the biological existence and that probably seems so completely obvious to somebody who you know is au fait with science whether they you know whether they're a scientist or not well so and i apologize if i'm interrupting but it's the obvious reality of of uh our life today but there's a lot of people i think it's currently in vogue i've talked to quite a few folks who kind of see as the goal of many of our pursuits as to extend life indefinitely a sort of uh you know a dream for many people is to live forever uh but in the in the technological world in the engineering world in the scientific world i mean that's that's the big dream to me it feels like that's not a dream it's i certainly would like to live forever uh like that that's the initial feeling the instinctual feeling because you know life is so amazing but then if you actually kind of like you've presented it if you actually uh live that kind of life you would realize that that's actually a step uh backwards that's a step down from the experience of this life in my sense that death is an essential part of life uh about an essential part of this experience death of all things so the thing the fact that things end somehow and the scarcity of things somehow create the beauty of this experience that we have yeah transhumanism doesn't look very attractive to me either but it also doesn't look very feasible um but that's a whole big topic that i'm not exactly an expert but i'll say but i but you know i'm of a certain age where my mortality is more pressing or more obvious to me than it once was okay um and and i don't dread that i don't see that as in a certain sense even the enemy okay you're not afraid of death well i'm afraid of lots of things in a in a in a conceptual way but it doesn't keep me awake at night okay um i i'm i think like most people i'm more afraid of pain than i am of death so i i don't want to put myself forward as some kind of hero that doesn't worry about these things that's not true but i i do think and maybe this is part of my christian outlook um that there is life beyond the grave um but i don't think that that it's life in this universe or in this um certainly not in this body and maybe not in a certain sense in this mind i mean you know christian christian belief in the afterlife is is that we will be resurrected we will be in a certain sense be with god i don't know what that means and i don't think anybody else really quite knows what that means but there are lots of ways that over history people artists and and and writers and so forth have pictured it um and these are all perhaps some of them helpful ways of thinking about it do you think it's possible to know what happens after we die um i i don't think we find out by near death experiences or those kinds of things but but i but i think that uh you know that we have sufficient i feel i have sufficient information if you like um in terms of god's revelation to be confident that that i will go somewhere else okay but it won't be here and i to me the aspirations of transhumanism are horrific i mean i think it would be a nightmare not a dream a nightmare you know to be somehow downloaded into a computer and live one's life like that i because it it completely discounts the integrity of our bodies as well as our minds i mean we aren't just disembodied minds it would not be me that was in the computer it would be something else if if that kind of download were possible of course it isn't possible and it's very long way from being possible but you know amazing things happen so we shouldn't be too certain so this is this is a place that uh again maybe taking a slight step outside uh wherever philosophizing a little bit uh let me ask you about uh human level or superhuman level intelligence uh the artificial intelligence systems do you what do you make from um from almost a religious or a perspective that we've been talking about of the special aspect of human nature of us creating intelligence systems that exhibit some elements of that human nature is that something again like we were talking about with transhumanism uh there's a feasibility question of how hard is it to actually build machines that human level intelligence or have something like consciousness or have all those kinds of human qualities and then there's the do we want to do that kind of thing so on both of those directions what do you think well okay so you know since your podcast is called ai i don't want to offend too many of your listeners out there that's but i but i i think one should be a little bit more modest about one's claims for ai than have typically been the case yeah i think that actually a lot of people in ai are somewhat chastened and so there there are more modest claims than are common with the transhumanists and yes and and so forth um and you know i used to play chess when i was a kid i was pretty good at it okay um won competitions and so on and so forth and i when i and i'm talking about when i was in high school i thought it was pretty unlikely that a computer would be able to become good at chess but i was dead wrong okay and so you know um how did that make you feel by the way when um t blue big i stopped playing chess seriously when i had when i encountered computers that could beat me okay i still play with my grandchildren a little bit but but um but yeah it it seemed like in a certain sense it became a solved problem uh when ai was able to do it better than i could so i think that there are ways in which today we've seen um computers do things which historically were regarded as being very characteristic of human intelligence and in that sense there there is some success to ai i also think that um you know there are certain things which one might think of as being ai which are you know completely widespread in our society i'm thinking about the internet search engines and so forth which are enormously influential and obviously do things more powerfully than any individual human or even any combination of humans could do much faster and and and accessing databases and so on and so forth is all of this is outstripped our human intelligence um i'm not sure the extent though to which that is really intelligence uh in the way that was traditionally meant but it's certainly amazingly um facile and um it it multiplies our ability to access human knowledge and and data and so forth so is that something is that is that enter the realm of something we should be concerned about so in the realm of religion you talk about what is good what is evil what is right what is wrong you have set of morals set of beliefs and when you have an entity come into the picture that uh that has quite a bit of power if we potentially look into the future and intelligence and capability um do you think there's something that religion can say about artificial intelligence or is that something you we shouldn't worry about until that arrives you think just like with the chess program um you know religious writers have thought about this for centuries uh you know there's been a long debate about what is what was historically called the plurality of worlds and it was actually more about whether there are places where other intelligent creatures live than it was about us creating them but but i think it's largely the same question it's almost like aliens like other intelligent so if there is other intelligent life in the universe what is its relationship to god okay that is in a certain sense the puzzle that religious thinkers and writers have thought about for a long time and there's a whole range of of different opinions about that i mean personally you know i think it's it's an interesting question but it's not a very pressing question at the moment um yeah and i think the same way about the the question of what happens if we're able to build a sentient robot for example um i think it's an interesting question and we'll have to think about it when that happens um but i think we're still quite a ways away from that and so i i don't have a good answer um but i think there's a literature that you one could tap um to think about if you want to start early on the question well let me ask you another impossible question from a religious or from a personal perspective what do you think is consciousness this this uh subjective experience that we seem to be having there's uh this there's uh the christian religion have something to say about consciousness does your own when you look in the mirror do you have a sense of what is consciousness um i think the bible doesn't have much in the way of answers about that directly in the sense that you're perhaps asking it which is more like i think you're asking for some kind of uh quasi scientific or maybe indeed scientific uh description that's really looking for one yes um i i think that i think that there it's an interesting question i think it's actually um it's a jump too far i think we have we don't even know the answer to the question what is the mind let alone consciousness so if you distinguish between those two things i think the question that's being addressed more directly um scientifically as well as in other ways it is what is the mind um and that is certainly a very topical question even in places like mit which is not historically involved with philosophical questions you know that people are doing neuroscience and so forth i think it's a very important question and i think that we're going to find that um we are not computers in other words i think uh the the commonplace theory of what mind is is is generally speaking by analogy that we are basically wet wetware okay um that we're some computer like um entity um and that that the analogy to digital computers is is is a pretty decent one i mean that that's of course a viewpoint which um you know which drives the aspirations of the transhumanists i mean they they so much believe that our minds are nothing other than you know in a certain sense some kind of implementation of software in biology that they say to themselves well of course we're going to be able to download it into a into a digital computer i don't think that's true i think it's most likely that quantum mechanics is very important in the brain uh it seems most unlikely that it's not to me i know that that's contrary to the opinions of many people but but that's my view and it's also a view for example of people like roger penrose and and people like that who've written about it um rather extensively and if that's the case then really my mind is not reproduce reducible to some kind of software which can be considered to be portable it is so uh connected to the hardware of my body that the two are inseparable okay and so if that is in fact what we find um as i suspect will be the case then the aspirations of the transhumanists will be very long incoming if at all um so i think that actually physics and chemistry um you know are in a are in a sense um involved with the brain and with in the mind but not in a very simple way like you know like the computer analogy um in and a much more complicated way and i and i also think that um it's philosophically ignorant to speak as if um when and if the actions of the brain are understood at the physical and chemical level that will mean that the mind will vanish as a concept you know that we'll just say no we're nothing but brains okay of course it won't i mean it may well be that our mind is an emergent phenomenon that comes out of the physics and chemistry and biology okay but it's also something that we have to encounter and take seriously and so um you know it's it's not the case that it that the mind is reducible to nothing but physics and chemistry even if it's embedded in you know continuously into physics and chemistry as i rather suspect it is um so i that that's my own view i mean another way of putting it is that the mind or the soul is not something added into humans as might have been the viewpoint um historically i do think there is you know there is something added to humans but it's not it's not the mind it's the spirit and that takes us beyond the physical it takes us beyond this universe but i but i don't think that that consciousness the mind etc etc is that thing which is necessarily added in so i i'm not be emergent in some way i'm not a substance dualist in that sense okay if you want to put it philosophically i mean uh but you see your sense is um so the mind and the intelligence and consciousness can be these emergent things do you do you have a hope a sense that science could help us get it pretty far down the road of understanding we will get much further than we have and we it'll be interesting um i mean right now our our methods of diagnosing the human brain are extremely primitive i mean the resolution that we have you know that comes out of uh out of nmr and and brain scans and so forth is miserable compared with what we need in order to understand the brain at the cellular level let alone at the atomic level um but you know we're making progress it's relatively slow progress but it's progress and people are working on it and we're going to get better at it and we'll find out very interesting things as we do um the time resolution is also completely hopeless compared compare with what we need to understand of a thought you know so um so there's a long way to go and we will get better at it um but i'm but i'm not at all worried as some people are and some people speak as if this is a good thing that somehow the concepts of humanity and the mind and religion and and consciousness are going to vanish because we're going to have you know complete uh physicochemical description of the brain in the near future that we're not going to have that and secondly even if we had it the mind and all these other things aren't going to vanish because of it well i i find kind of compelling the the notion that whoever created this universe uh and us uh did so to understand itself himself i mean there's a there's a there's a powerful self reflection notion to this whole experiment that we're a part of i certainly think that god takes delight in his creation and that it was created for that delight as much as it was um for any other reason and that you know that therefore are there's reason to be hopeful and and awestruck by the creation whether it's on the very small or on the very large i'm not sure if you're familiar there's something called the simulation hypothesis well that's been fun to talk about with the computer scientists and so on which is a kind of thought experiment that proposes that um you know the entirety of the world around us is a kind of a computer program that's a simulation and then we're living inside it i think there's um i think from a certain perspective that could be consistent with a religious view of the world i mean you could just use different terms uh basically uh what are your but it's a it's a it feels like a more um modern updated version of that but what is what's what's your sense of this uh the simulation hypothesis do you find interesting useful to think about it do you find it ridiculous did you find it fun what are your thoughts uh it's fun and it's been of course the subject of various movies yeah um that that some of which are very well known um you know i don't think it makes sense to think of it as a simulation hypothesis in the sense that we're really lying in uh banks um of of uh on banks of of beds having our energy drained away from us um and and the simulation is going on in our individual brains that that makes no sense to me at all i don't think that's what's meant by the simulation hypothesis as you're using it now but i think that there is a um there is very little distinction between saying that a an intelligent creator has set up the universe according to his will and his plan and set it in motion and is allowing it to run out maybe as christians say he's sustaining it actually um by his word of power it says in the book of the letter to hebrews okay um in in in in this amazingly consistent and um integrated way um i don't think there's very much difference between saying that and saying that it's a simulation okay i mean i think it's almost the same thing okay but i but i think from but i think it's important to recognize that the simulation in that concept the simulation and the creation or the universe are the same thing okay in other words it's a simulation you know that is billions of light years across okay yeah um i mean there's a sense in which it helps one understand especially if you're not religious that there is something outside of the world that uh we live in that there's something bigger than the world we live in um and that i mean it's just another perspective on uh that humbles humbles you um so in that sense one shortcoming of that is is the following is of the of the analogy is this that we think of a simulation as something take taking place in the universe you know when we it's it's taking place in my computer okay i don't think that's the right analogy for um a christian view of creation okay i don't think it's taking place in some other universe that god has made okay i i think maybe it's taking place in the mind of god christians might hypothesize also but i but i think that that that it's important to recognize that christian theology at any rate is that god is not one of the entities in the universe and and presumably therefore is very different from a simulation that we might run on a computer let me ask you adam and eve even adam ate of the fruit of the tree of knowledge of good and evil does this is this story meaningful to you what does the story mean to you yeah i it is meaningful to me um i i take the you know the writings of the bible very seriously and i think that most christians regard them as having some kind of authoritative um role in their in their in their faith um what do i get from it i mean i think the most important thing that christians get from the story of adam and eve and they're eating the apple and so forth is that the relationship between humans and god is broken has been broken by man's disobedience that's what the the story of adam and eve and the apple is all about and um that that broken relationship is for christians what jesus came to redeem came to overcome that brokenness and uh restore uh that relationship with god um uh to some extent at any rate on earth and and ultimately um you know in in the in eternity to restore it fully so that's really what christians mean and gain from the story of adam and eve of course lots of people ask the questions about how sort how literally should we take these stories of particularly the first few few chapters of genesis which is an important question but but i mean but we tend to um get bogged down with it a bit too much i think we should take away the message um and i think the the the uh what the what actually we would have seen if we'd been there okay is something which is a matter of speculation and it's certainly not terribly important from the point of view of christian theology but it seems like a very important moment um as a man of faith do you um do you do you wish that uh i think it was eve first uh yeah well see do you wish that by the way it was just a fruit as a few what you said it very carefully as the fruit fruit of the tree right uh do you wish they wouldn't have eaten of the tree i mean this is a back to our discussion of suffering was that like an essential thing that needed to happen you're gonna have to read paradise lost to get your answer to that beautifully put okay well let me ask the the biggest question one that you also touch in your book but one that i asked every once in a while is what is the meaning of life the meaning of my life is many different things okay but it but they are all kind of centered around um relationships um i mean for a christian one's relationship with god is a crucial part of the meaning of life but one's relationship with one's family wife's wife parents children grandchildren in my case um and so forth those are crucially important um these are all the places where people whether they're religious or not find meaning um but ultimately um i think a person who has faith in a creator um who we think has a an intention or many intentions but a but a but a will um in respect of the world as a whole that's a crucial part of meaning and the idea that my life might have some small significance in the plan of that creator is an amazingly powerful idea that give that brings meaning um i i tell a story in my book that um when i was a student before i became a christian i read a philosophy book with whose approximate title was um what you know what is the meaning of life and you know that book basically said there is no meaning to life you have to make up the meaning as you go along and i think that's probably the the predominant secular view is these days that there is no real meaning but you can make up a meaning and that will give you meaning into your life um i don't subscribe to that view anymore um i think there is more meaning than that um but i do think that those things which give meaning to our life are very important and we should emphasize them and you you have said that as the part of the as the part of that meaning is the part of your faith uh love and loyalty are key parts so can you try to say what is uh love and loyalty like what what does it mean to you what does it look like if you were to give advice to uh to your children grandchildren of what to look for in in looking for loyalty and and and love what would you try to say well i think it's something like yielding your will or desire to another um it's valuing others more highly or at least as highly as yourself but that's just the start of it because true love you reach a point where you are you feel compelled by the other uh and that i think to some people sounds very scary but actually it's terrifically liberating um and i think that love then brings you into service towards another and i'm you know reminded of um the phrase from the anglican uh prayer book where it talks about um jesus whose service is perfect freedom in other words for us christians to serve god is what perfects our freedom and i think there is an amazing love is um is in part kept captivity but in a kind of paradoxical sense it's also an amazing freedom love is freedom i don't think there's a better way to end it we started with fusion energy and ending on love in there's a huge honor to talk to you thank you so much for your time today thanks it was a pleasure thanks for listening to this conversation with ian hutchinson and thank you to our sponsors sun basket and power dot please consider supporting this podcast by going to sun basket.com slash lex and use code lex at checkout and going to power dot.com slash lex and use code lex at checkout click the links buy the stuff even just visiting the site is really the best way to support this podcast because it they what's where's the generation of the energy coming from? Are they smashing into each other? Yeah eventually I mean in a fusion reactor there will be deuterons and tritons and they will be smashing in. They will be very hot there'll be a hundred million degrees Celsius or something so they're moving thermally with very large thermal energies in random directions and they will collide with one another and have fusion reactions. When those fusion reactions take place energy is released large amounts of energy is released in the form of particles. One of the particles that's released is an alpha particle which is also charged and it's also confined and that alpha particle stays in the in the in the donut and heats the other particles that are in that donut so it transfers its energy to those and they it keeps them hot. There are there's some leaking of heat all the time a little bit of radiation some transport and so forth. There's also a neutron released from that reaction the neutron carries out four fifths of the fusion energy and that will have to be captured in a blanket that surrounds the chamber in which we take the energy drive some kind of electrical generator from you know thermal thermal engine gas turbine or something like that and power the power. You got energy. So where do we stand? Where do we stand? I'm getting this thing to be something that actually works that generates energy. Well there have been experiments that have generated net nuclear energies or nuclear powers in the vicinity of you know a few tens of megawatts for a few seconds. So that's you know 10 megajoules that's not much energy it's a few donuts worth of energy okay. A literal donut. But we have studied how well tokamaks can find plasmas and so we now understand in rather great detail the way they work and we're able to predict what is going to be required in order to build a tokamak that becomes self sustaining that becomes essentially ignited or very so close to ignited that it doesn't matter. And at the moment at least if you use the modest magnetic field values still very strong but limited magnetic field values you have to build a very big device. And so we are at the moment worldwide fusion research is at the moment in the process of building a very big experiment that's located in the south of France. It's called ITER which means the way or just means the international tokamak experimental reactor if you like. And that experiment is designed to reach this burning plasma state and to generate about 500 megawatts of fusion power for hundreds of seconds at a time. It'll still only be an experiment. It won't put electricity on the grid or anything like that. It's to figure out whether it works and what the remaining engineering challenges are. It's a scientific experiment. It won't be engineered to run round the clock and so on and so forth which ultimately one needs to do in order to make something that's practical for generating electricity. But it will be the first demonstration on earth of a controlled fusion reaction for you know long time periods. Is that exciting to you? It's been an objective that is in many ways motivated my entire career and the career of many people like me in the field. I have to admit though that one of the problems with ITER is that it's an extremely big and expensive and long time to build experiment and so it won't even come into operation until about 2025 even though it's been being built for 10 years and it was designed for 30 years before that. And so that's actually one of the big disappointments of my career in a certain sense which is that we won't get to burning fusion reaction until well past the first operation of ITER and whether I'm alive or not I don't know but I certainly will be well and truly retired by the time that happens. And so when I realized maybe some years ago that that was going to be the case it was a discouragement to me let's put it like that. But if we can try to look maybe in a ridiculous kind of way look into a hundred years from now two hundred years five hundred years from now and we you know there's folks like Elon Musk trying to travel outside the solar system. I mean the amount of energy we need for some of the exciting things we want to do in this world if we look again hundred years from now seems to be a very large amount. So do you think fusion energy will eventually sometime into your retirement will be basically behind most of the things we do? Look I absolutely think that fusion research is completely justified. In fact we should be spending more time and effort on it than we currently do. But it isn't going to be a magic bullet that somehow solves all the problems of energy. By the way that's a generic statement you can make about any energy source in my view. I think it's a grave mistake to think that science of any sort is suddenly going to find a magic bullet for meeting all the energy needs of society or any of the other needs of society by the way. But and we can talk about that later. But fusion is very worthwhile and we should be doing it. And so my disappointment that I just expressed was in a certain sense of personal disappointment. I do think that fusion energy is a terrific challenge. It's very difficult to bring the energy source of the sun and stars down to earth. This does contrast in a certain sense with fission energy. By contrast fission energy efficient to build a fission reactor proved to be amazingly easy. You know we did it within a few years of discovering nuclear fission. People had figured out how to build a reactor and did so during the Second World War. Which is by the way fission is how the current nuclear power plants work. And so we have nuclear energy today because fission reactors are relatively easy to build. What's hard is getting the materials and that's just as well because if everyone could get those materials there would be weapons proliferation and so forth. But it wasn't all that long after even the discovery of nuclear fission that fission reactors were built and fission reactors of course operated before we had weapons. So I think nuclear power is obviously important to meet the energy challenges of our age. It is completely intrinsically completely CO2 emissions free. And in fact the wastes that come from nuclear power whether it's fission or fusion for that matter are so moderate in quantity that we shouldn't really be worried about them. I mean yes fission products are highly radioactive and we need to keep them away from people but there's so little of them it's that keeping them away from people is not particularly difficult. And so while people complain a lot about the drawbacks of fission energy I think most of those complaints are ill informed. We can talk about you know the challenges and the disasters if you like of fission reactors but I think fission in the near term offers a terrific opportunity for environmentally friendly energy which in the world as a whole is rapidly being taken advantage of. You know China and India and places like that are rapidly building fission plants. We're not rapidly building fission plants in the US although we are actually building two at the moment, two new ones. But we do still get 20 percent of our electricity from fission energy and we could get a lot more. So it's clean energy. So it's clean energy. Now again the concern is there's a very popular HBO show and just came out on Chernobyl. There's the Three Mile Island, there's Fukushima, that's the most recent disaster. So there's a kind of a concern of yeah I mean nuclear disasters. Is that, what do you make of that kind of concern especially if we look into the future of fission energy based reactors? Well first of all let me say one or two words about the contrast between fission and fusion and then we'll come on to the question of the disasters and so forth. Fission does have some drawbacks and they're largely to do with four main areas. helps convince them to sponsor it in the future if you enjoy this thing subscribe on youtube review it with five stars on apple podcast support on patreon or connect with me on twitter at lex friedman spelled somehow without the letter e just f r i d m a n and now let me leave you with some words from arthur c clark finally i would like to assure my many buddhist christian hindu jewish and muslim friends that i am sincerely happy that the religion which chance has given you has contributed to your peace of mind and often as western medical science now reluctantly admits to your physical well being perhaps it is better to be unsane and happy than sane and unhappy but it is the best of all to be sane and happy whether our descendants can achieve that goal will be the greatest challenge of the future indeed it may well decide whether we have any future thank you for listening and hope to see you next time One is do we have enough uranium or other fissile fuels to supply our energy needs for a long time? The answer to that is we know we have enough uranium to support fission energy worldwide for thousands of years but maybe not for millions of years okay. So that's resources. Secondly there are issues to do with wastes. Fission wastes are highly radioactive and some of them are volatile and so for example in Fukushima the problem was that some fraction of the fission wastes were volatilized and went out as a cloud and polluted areas with cesium 137, strontium 90 and things like that. So that's a challenge of fission. There's a problem of safety beyond that and that is that in fission it's hard to turn the reactor off. When you stop the nuclear reactions there is still a lot of heat being liberated from the fission products and that is actually what the problem was at Fukushima. The Fukushima reactors were shut down the moment that the earthquake took place and they were shut down safely. What then happened after that at Fukushima was you know there was this enormous tidal wave many tens of meters high that came through and destroyed the electricity grid feed to the Fukushima reactors and their cooling was then turned off and it was the after heat of the turned off reactors that eventually caused the problems that led to release. And so that's a safety concern and then finally there's a problem of proliferation and that is that fission reactors need fissile fuel and the technologies for producing and enriching and so forth the fuels can be used by bad actors to generate the materials needed for a nuclear weapon and that's a very serious concern. So those are the four problems. Fusion has major advantages in respect of all of those problems. It has more longer term fuel resources, it has far more benign waste issues, the radioactivity from fusion reactions is at least a hundred times less than it is from fission reactions. It has essentially none of this after heat problem because it doesn't produce fission products that are highly radioactive and generating their own heat when it's turned off. In fact the hard part of fusion is turning it on not turning it off. And finally you don't need the same fission technology to make fusion work and so it's got terrific advantages from the point of view of proliferation control. So those are the four main issues which make fusion seem attractive technologically because they address some of the problems of fission energy. I don't mean to say that fission energy is overwhelmingly problematic but clearly there have been catastrophes associated with fission reactors. Fukushima actually is I think in many ways are often overstated as a disaster because after all nobody was killed by the reactors essentially, zero. And that's in the context of a disaster and tsunami that killed between 15 and 20,000 people instantane more or less instantaneously. So you know in the scale of risks one should take the view that in my estimation that fission energy came out of that looking pretty good. Okay. Of course that's not the popular conception. Okay. Yes that's good. I mean with a lot of things that threaten our well being we seem to be very bad users of data. We seem to be very scared of shock attacks and not at all scared of car accidents and this kind of miscalculation. And I think from everything I understand nuclear energy, fission based energy goes into that category. It's one of the safest, one of the cleanest forms of energy and yet the PR, whoever does the PR for nuclear energy has a hard job ahead of them at the moment. Well I think part of that is their association with nuclear weapons because when you say the word nuclear people don't instantly think about nuclear energy, they think about nuclear weapons. And so there is perhaps a natural tendency to do that. But yes I agree with you, people are very poor at estimating risks and they react emotionally not rationally in most of these situations. Can we talk about nuclear weapons just for a little bit? So fission is the kind of reaction that's central to the nuclear weapons we have today? That's what sets them off. That's what sets them off. So if we look at the hydrogen bomb maybe you can say how these different weapons work. So the earliest nuclear weapons, the nuclear bombs that were dropped on Japan etc. etc. were pure fission weapons. They used enriched uranium or plutonium and their energy is essentially entirely derived from fission reactions. But it was early realized that more energy was available if one could somehow combine a fission bomb with fusion reactions. Because the fusion reactions give more energy per unit mass than fission reactions. And this was called the super, you might have heard of the expression the super or more simply hydrogen bombs. Bombs which use isotopes of hydrogen and the fusion reactions associated with them. Like you said it's hard to turn on. It's hard to turn on because you need very high temperatures and you need confinement of that long enough for the reactions to take place. And so a bomb actually, a thermonuclear bomb or a hydrogen bomb has essentially a chemical implosion which then sets off a fission explosion which then sets off and compresses hydrogen isotopes and other things, which I don't know because I've never had a security clearance. So I can't betray any secrets about weapons because I've never been party to them because I know a lot about this problem I can guess. And sets off fusion reactions in the middle. So that's basically it's that sequence of things which produce these enormous multi megaton bombs that have very large yields. And so fusion alone can't get you there. It is actually possible to set off or to try to set off little fusion bombs alone without the surrounding fission explosion and that is what is called laser fusion. So another approach to fusion which actually is mostly researched in the weapons complex, the national labs and so forth because it's more associated with the technologies of weapons is inertial fusion. So if you decide instead of trying to make your plasma just sit there in this Taurus and in the tokamak and be controlled steady state with a magnetic field, if you're willing to accept that I'll just set off an explosion and then I'll gather the energy from that somehow I don't quite know how but let's not ask that question too much. Then it is possible to imagine generating fusion alone explosions and the way you do it is you take some small amount of deuterium tritium fuel you bombard it with energy from all sides and this is what the lasers are used for extremely powerful at lasers which compresses the pellet of fusion and heats it. It compresses it to such a high density and temperature that the reactions take place very very quickly and in fact they can take place so quickly that it's all over with before the thing flies apart. Wow. And that is. Heated up really fast. That is inertial fusion okay. Is that useful for energy generation for outside? Not yet I mean there are those people who think it will be but you may have heard of the big experiment called the National Ignition Facility which was built at Livermore starting in the late 1990s and has been in operation since around about 2010. It was designed with the claim that it would reach ignition fusion ignition in this pulsed form where the reactions have got over with so quickly before the thing whole thing flies apart. It didn't actually reach ignition and it doesn't look as if it will although you know we never know maybe people figure out how to make it work better. But the answer is in principle it seems possible to reach ignition in this way maybe not with that particular laser facility. Are you surprised that we humans haven't destroyed ourselves given that we've invented such powerful tools of destruction? Like what do you make of the fact that for many decades we've had nuclear weapons now speaking about estimating risk at least to me it's exceptionally surprising I was born in the Soviet Union that big egos of the big leaders when rubbing up against each other have not created the kind of destruction everybody was afraid of for decades. Well I must say I'm extremely thankful that it hasn't I don't know whether I'm surprised about it I've never thought about it and from the point of view of is it surprising that we've we've avoided it I'm just very thankful that we have I think that there is a sense in which cooler heads have prevailed at crucial moments I think there is also a sense in which you know mutually assured destruction has in fact worked as a policy to restrain the great powers from going to war and in fact you know the the the fact that we haven't had a world war you know since the 1940s is perhaps even attributable to nuclear weapons in a kind of strange and peculiar way but I think humans are deeply flawed and sinful people and I certainly don't feel that we're guaranteed that it's going to go on like this. And we'll talk about the sort of the biggest picture view of it all but let me just ask in terms of your worries of if we look a hundred years from now we're in the middle of what is now a natural pandemic that from the looks of it as fortunately as not as bad as it could possibly been if you look at the Spanish flu if you look at the history of pandemics if you look at all the possible pandemics that could have been that folks like Bill Gates are exceptionally terrified about we've I know many people are suffering but it's better than it could have been so and now we're talking about nuclear weapons in terms of existential threats to us as sinful humans what worries you the most is it nuclear weapons is is it natural pandemics engineered pandemics nanotechnology in my field of artificial intelligence some people are afraid of killer robots and robots yeah is there do you think in those existential terms and do any aspect to any of those things were you I am certainly not confident that my children and grandchildren will experience the benefits of civilization that I have enjoyed I think it's possible for our civilizations to break down catastrophically I also think that it's possible for our civilizations to break down progressively and I think they will if we continue to have the explosion of population on the planet that we currently have I mean it's it's quite it's quite wrong to think of our problems as mostly being co2 if we can just solve co2 then we can go on having this you know continually expanding economy everywhere in the world of course you can't do that okay I mean there is a finite you know bearing capacity of our planet on the resources of our planet on the resources of our planet and and we can't continue to do that so I think there are lots of technical reasons why a continually expanding economy and and and civilization is impossible and therefore actually I'm as much nervous about the fact that our population is eight billion or something right now worldwide as I am about the fact that you know a few million people would be would be killed by COVID 19 I mean I don't want to be callous about this but from the big picture it seems like that's much more of a problem over population people not dying is ultimately more of a problem than people dying so you know that probably sounds incredibly callous to your listeners but I think it's simply you know a sober assessment of the situation is there is there ways from the way those eight billion or seven billion or whatever the number is live that could make it sustainable you know because you've kind of implied there's a kind of we have especially in the West this kind of capitalist view of really consuming a lot of resources is there a way to like if you could change one thing or a few things what would you change to make this life make it more likely that your grandchildren have a better life than you well okay so let's talk a bit about energy because that's something I know a lot a lot about having thought about it most of my career in order to reach steady state co2 level okay that's acceptable in terms of global climate change and so on and so forth we need to reduce our carbon emissions by at least a factor of ten worldwide okay what's more you know the average energy consumption and hence co2 emission of people in the world is less than a tenth of what we per capita of them what we have in the West in America and Europe and so forth so if you have in mind some utopia in the future where we've reached a sustainable use of energy and we've also reached a situation in which there is far less inequity in the world in the sense that people have share the energy resources more uniformly then what that is equivalent to would be to reduce the co2 emissions in Western economies not by a factor of ten but by a factor of a hundred in other words has to go down to one percent of what it is now okay so you know when people talk about you know let's use natural gas because you know maybe it only uses sixty percent of the energy of coal it's complete nonsense that's not not even scratching the surface of what we would need to do so you know is that going to be feasible I very much doubt it and therefore I actually doubt that we can reach a level of energy of fossil energy use that is one percent of the current use in the West without totally dramatic changes either in you know our society our use of of energy and so forth which actually of course is much of that energy is used for producing food and so on and so forth so it's actually not so obvious that we can we can get we can cut down our energy usage by that factor or we've got to reduce the human population so you run up against that number that's increasing still and you don't think that could be it's not it's not that it's not it's not depressing it's it's difficult like many truths are do you have a hope that there could be a technological solution in short no there is no technological solution to for example for population control I mean we have the technology just you know to prevent ourselves bearing children that's not a problem technology is in okay solved the challenge is society the challenge is human choices the challenge is almost entirely human and sociological not technology not technology and when people thought talk about energy they thought they think that there's some kind of technological magic bullet for this but there isn't okay and and there isn't for the reasons I just mentioned not because it's obvious there isn't but actually there isn't and and in in any case that it's true of energy it's true of pollution it's true of human population it's true of most of the big challenges in our society are not scientific or technological challenges they're human sociological challenges and that's why I think it's a terrible mistake even for folks like me who work at you know well the high temple of science and technology in in America and maybe in the galaxy yeah I mean you know it's it's MIT it's at MIT best university in the world it's it's a terrible mistake if we give the impression that technology is going to solve it all technology will make tremendous contributions and I think it's it's worth working on it but it's a disaster if you think it's going to solve all of our problems and and actually you know I've written a whole book about the question of of scientism and the and the over emphasis on science both as a way of of solving problems through technology but also as a way of gaining knowledge I think it's not all the knowledge there is either yeah I think that book and your journey there is fascinating so maybe you can go there can can you tell me about your on a personal side your the personal journey of your faith of Christianity and your relationship with with God with religion in general yeah in my in my latest book Can a Scientist Believe in Miracles I I give a first I devote most of the first chapter to telling how how I became a Christian why I became a Christian I I didn't grow up as a Christian which is fascinating I mean you didn't grow up as a Christian so you you've discovered the beauty of God and physics at the same time concurrent that's a very poetic way of putting it but yes I would accept that I became a Christian when I was an undergraduate at Cambridge University I I had you know I had gone to a school in which there was religion kind of was part of the society there were prayers and at the at the at the daily you know gathering of the of the students of the assembly of the students but I but I didn't really believe it I just sort of went along with it and it wasn't particularly you know aggressive or benign you know benign it just sort of was there but I didn't believe it I didn't didn't make much sense to me but when I but I came across Christians from time to time and when I went to Cambridge University two of my closest friends turned out were Christians and I think it was that was the most important influence on me that that here were two people who were really smart like me I'm giving you my yeah my impressions the way I the way I felt at the time and and they thought Christianity made sense and and you know testified to its significance in their lives and so that was a very important influence on me and I and ultimately I mean the reason I I hadn't I hadn't I didn't see Christianity as some kind of great evil the way it's sometimes portrayed by the by the radical atheists of this century I mean I think that's nonsense but but but I so I think there were certain attractive things if you go to a university like Cambridge you know you're surrounded by by by Western culture you know from from about you know the 15th century onwards and that saturated with Christian art and architecture and so forth and so it's hard it's hard not to recognize that Christianity is in fact the foundation of Western society in Western culture most Western civilization so so I mean maybe I was in that sense favorably disposed towards Christianity as a religion but as a personal faith it didn't mean anything to me but I became convinced really of two things one is that the evidence for the resurrection of Jesus Christ is actually rather good I mean it's not a proof it's not kind of some some kind of scientific demonstrate or mathematical demonstration but it's actually extremely good it's not scientific evidence by and large it's historical evidence historical evidence yeah so that was one thing and the other thing that came to me when I was at Cambridge it became clear that Christianity ultimately is not you know some kind of moral theory or philosophy or something like that it is or elite or at least it claims to be a personal relationship with God which is made possible you know by what Jesus did and on the cross and his life and his teaching and and it's a personal call to a relationship with God and that had I'd never thought of it in those terms when I was you know when I was younger and that that thought became attractive to me I mean I think most people find the person of Christ and just teachings you know compelling insert in a certain sense what do you mean by personal do you mean personal for you like a relationship like it's a meditative like you specifically you Ian have a connection with God and and then the other side you say personal with the actual body the person of Jesus Christ so all of those things what do you mean by personal connection and why that was well so as I'm sorry for the stupid questions no it's okay no problem as a Christian I believe that I have a relationship with God which is best expressed by saying that it's personal and that comes about because you know Jesus through his acts has reconciled me with God me a sinner me someone full of sins of failings of ways in which I don't live up to even my own ideals let alone the ideals of a holy God have been reconciled to the creator of everything and and so Christians myself included believe that prayer is in a certain sense a connection with God and there are times when I have felt you know that God spoke to me I don't mean necessarily orally in words but showed me things or enlighten me or inspired me in ways that I I attribute to him so I see it as a as a two way you know relationship in a certain sense of course it's a very asymmetrical relationship but nevertheless Christians think that it's a two way it's a two way street we're not just talking into the air when we say we won't I'm going to pray for someone in this two way communication is there a way that you could try to describe on a podcast what is God what is God like in your view if you try to describe is it a force is it a set is it a for you intellectually is a set of metaphors that you use to reason about the world is it is it is it kind of a computer that does some computation that's the infinitely powerful computer or is it like Santa Claus a guy with a with a beard on the cloud like I don't mean I don't mean what God actually is I mean in your limited cognitive capacity as a human what do you actually what do you find helpful for thinking of what God actually looks like what is God well let me start by saying none of the above okay I mean clearly God in the Christian God the God of Abraham Isaac and Jacob etc it is is not any of those things because all of those things you just mentioned are phenomena or or or entities in the created world and the most fundamental thing about monotheism as you know Abraham and Moses and so forth handed it down is that God is not an entity within the creation within the universe that God is the creator of it all and that's what Genesis first two chapters of Genesis is really about is it's not it's not about telling us you know how God created the world it's about telling us and telling the early Hebrews that God created the world okay and that therefore he is not you know simply an entity within it on the other hand you know our finite minds have a pretty hard time encompassing that so so one has to therefore work in terms of metaphors and images and and so forth and I think we would know very little about who God is if we if it was simply up if we were simply left to our own devices you know if if we were just you know here you are you're in the universe try to figure out who made it and and so forth well you know philosophers think they can do a little bit of that maybe and theologians think that they can do a little bit more but but Christians think that God has actually helped us along a lot by revealing himself and and we say that he's revealed himself supremely in the person of Jesus Christ and so you know when Jesus says to his disciples if you've seen me you've seen the Father then that is in a certain sense a watchword for answering this question for Christians it is that supremely if we want to help ourselves understand who God really is we look to Jesus we look to what he did we look to what he said and so forth and we believe that he is one with the Father and that's why we believe you know in the Trinity I mean it's basically because that revelation is extremely central to Christian belief and teaching so in that in that sense