 Welcome everyone. My name is Alain Blaggian. I'm the Dean here in the Zalvin and Sonia Afian College of Science and Engineering. And it gives me great pleasure today to introduce our speaker for our seminar series. Adek Angluwan is here from MIT to talk about verification of nuclear warheads using physical cryptography. So the abundance of nuclear weapons in the world is one of the biggest dangers to human civilization. And ambitious aggressive nuclear disarmament treaties are necessary to reduce this existential threat. New technologies, however, are necessary to enable the verification of those treaties while protecting the nuclear secrets of the participants in order to make the treaties effective. So I'll cut short the more full-blown description as we're going to hear about it. But the point that I would make here is that I think it's great to see how deep expertise in one field leads in very interesting ways to applications and things that are maybe outside of what we study. So sometimes your teacher tells you, well, you're going to learn this and you say, what do I need to know that for? So sometimes you don't know where the borders end and where tomorrow's opportunities begin. So these interdisciplinary applications I think are very interesting in general. And today we're lucky to hear from a world expert on one such very important application. So Adek Angluwan is an assistant professor at MIT's Department of Nuclear Science and Engineering. I graduated in FISMA school here in Yerevan in 93 and studied physics at MIT. Continued to University of Illinois at Urbana-Champaign in experimental nuclear physics at Los Alamos. And a very impressive career in academia and in national labs and in industry. And I'm sure he'll make references to his past. And so join me in welcoming Dr. Armina here at the UAE. So thank you very much. Ladies and gentlemen, for the eloquent introduction. Thank you everyone for coming. So let me just describe what I'll be talking about. I'll be talking about coming off. So I'll first talk about the history of the school back. It's where they come from. I'll talk about the Manhattan Project and the Trinity Test. They were essentially big enormous projects which created the nuclear weapons in the United States. What are nuclear weapons? How do they work? What's the basic physics behind nuclear weapons? I'll try to keep this talk as colloquial as possible for general use. I'll use some analogies. And then what happened after the weapons were created? The 70 years the nuclear arms race that took place during the Cold War really changed the perception of safety and security in this world. We still live in the legacy of that. And then the arms reduction process which tried to control this enormous danger that the humanity and the human planet itself was facing. So how do we treat, how do we do these treaties? What are the problems? Why is it so difficult to pass these treaties? And why are they as limited as they have been? And how do we solve these limitations? How do we use a lot of the problems that you have to deal with are political but some of them are technological. So us, scientists, engineers, technologists, what can we do to contribute to this enormous social problem? Alright, so let's start with the Manhattan Project. Trinity, which has nothing to do with nuclear aviation, where the first nuclear device was detonated in the summer of 1945. It was a result of a massive project that took place about five years in the United States and it evolved scientists from all over the world to create this basically super weapon, the ultimate weapon. And one of the original ideas Albert Einstein was, one of the first people, was the news board, was a guy who came up with the idea of using chain reaction to reduce this enormous amount of energy in a very short amount of time. So this is the actual first device over here. This is a fellow with a cowboy hat sitting next to me for one of these years. And this was the actual first bomb and this is actually the first nuclear detonation. But this was not a weapon yet. This led to two actual nuclear weapons which were. So before going to that, talking about the people who did this and why people did this, why did physicists and engineers who generally tend to be fairly liberal people, who love our very peaceful people, why did it develop this huge weapon? So here's a list of the incomplete list of the 25 Nobel Prize laureates who were involved on the Manhattan Project. And only part of them are Americans. Lots of them were Germans, they were Jews, there were some Russians, there were even some Armenians who worked on this project. But there's a huge, for any physicist, names like Niels Bohr, Ernico Fermi, Norman Ramsey, Hans Bethe, Richard Feynman. All of these were luminaries of physics. So why did these people develop the nuclear bomb? So to not understand the reason is this fellow over here, Werner Heisenberg, who came up with Heisenberg as a strategic principle. He was working for the Nazi program to develop nuclear weapons. So basically the Americans developed the American physicists, like I say, were really wanting to develop the nuclear weapon because they wanted to get there first for Hitler to do that. Because they knew what Hitler do wanted to do with nuclear weapons. Things did not go the way people imagined them. Ultimately, the nuclear weapon was not used, or Nazi's was used for the Japan. And then afterwards, Andrei Sakharov, another Nobel Prize laureate, got the Peace Prize much later, but he was the head of the, essentially, one of the biggest people working in the Soviet program to develop nuclear weapons. So the result of this program was two weapons, the Riesel Boy and Feynman, were dropped on two Japanese cities, which completely destroyed the cities and killed something like 200,000 people. The energy released in one nuclear weapon was equivalent to 20,000 tons of explosives. I'll be using this term, 20 kilotons for 20 kilotons equivalent. It means 20,000 tons of energy that 20,000 tons of explosives would release. So a bomb which maybe weighs like a ton would release something like 20,000 tons of explosives. One bomb was enough to completely destroy one city. But furthermore, what was perhaps even worse was that it led to the arms race between the United States, the Soviet Union, China, Britain, France, Pakistan, India, who all started developing nuclear weapons. By the way, do you know where, you probably have heard this little boy in Fatima? The names of the first bomb, do you know where the names actually come from? Little boy was named after Rusmold, the president of the United States, because Rusmold was, he was handicapped, he was sitting in the chair, and his nickname, there was Little Boy, they named after him. Can you guess who Fatima was? Very good. The other big politician, right? So, how did these nuclear weapons work? What's the basic principles behind their work? So there's two, in general, two type of weapons. To take a look at the article, efficient weapons is like the basic nuclear weapon. And then there's a fusion weapon, which are thermo-nuclear weapons, which are even more powerful than regular nuclear weapons. Their power is essentially estimated to be infinite. You can make them infinitely large. The biggest one, which was developed by Andrey Sakharov, was something like 20,000 times more powerful than a bomb that was dropped on the ground. So how does, what's the basic physics behind the nuclear weapons? How does that work? So the basic process that is exploited in any kind of a nuclear power process, whether it's a bomb or what's a nuclear reactor, is efficient. So again, I think we have got this renewed nuclear, which is fairly unstable, it's constantly weakening, it wants to break up. And you slam and then it breaks. And that excites the nucleus. And that's not that the nucleus breaks up into two what are called fission fragments, or dodger products. In a process, which is very important, something like between two and three neutrons are being emitted. And if they're lucky, if they're with this very progressive process, one of them might try with another uranium nucleus and force that one to decay. Now there's more neutrons. And this process keeps replicating itself over and over and over again. Number of neutrons is increasing, explanation. One of the nuclei that are decaying is the increasing explanation. And any exponential process can be taken to a point where essentially all the nuclei in the material will result in a burn. It will end up as a term that we use to burn nuclear material. However, it's not so easy to do it just because you have a piece of uranium does not mean this is going to work. And that has to do with the fact that this process is fairly probabilistic. So you have to have lots of material before that will happen. So if you have a little chunk of uranium, neutrons go through. Some of them, if the uranium is very thin, because it's very thin, because of probabilistic process, will just go through and do nothing. Some of them with small probability will cause an interaction. You'll get three neutrons will come out. Two of them will come out once. They might or might not cause another fission. And then these ones will come out too. At the end, this will have this process, which is a chain reaction, but this chain reaction dies out. It's like trying to lid a log with a match, with a little match. And it causes a little burn, but the burn dies out. So the reaction chain dies out. However, if you make this uranium much bigger, much thicker, now these neutrons have nowhere to go. They're eventually going to interact one way or another, because there's so much material in the way. So you'll cause some fissions. There's going to be more. They're going to get more neutrons. These neutrons are going to see more material. They are going to cause more fissions, so on and so on and so on. And if you're going to have essentially this explosive process, where the process instead of exponentially dying out, is going to exponentially go. So in terms of some basic mathematics, the dependence of number of fusions on time grows exponentially. There's three factors over here. This is k minus 1, the so-called k factor I'll talk about. T is time, and tau is the lifetime of the neutrons in the metal. But basically think of this as some exponential which depends on time, and it has a factor which depends on the material, on the object itself. So how does k minus 1 depend on the material itself? And how can we change this k minus 1? So if k minus 1 is negative, so from what you remember about exponentials, if you have a negative sign in an exponential, exponential decays out like this. Nothing happens. It's a subcritical process. Directive dies out, you know, of course. k minus 1 primarily depends on the material type, depends on the particular isotope that the material is made out of, and it varies from the material to the geometry of the material. So if it's very thin, like I said before, k minus 1 is going to be negative, and the process is going to die. But if it's thick, k minus 1 is going to be positive. And now instead of having a subcritical exponential decay, you're going to have a supercritical exponential increase which will diverge and eventually consume the whole material itself. That's what an explosion is. So two examples of where this is important, nuclear react, when we think of nuclear fission, we think of two extreme cases. One of them is controlled nuclear reactions, and one of them is uncontrolled nuclear reactions. Uncontrolled nuclear reactions are nuclear explosions. Controlled nuclear reactions are happening inside nuclear reactors. So this k minus 1 that determines pretty much everything in life. For the nuclear reactors, it's pretty much stuck near zero. You can push it above zero, but it always falls back to zero. If the reactor is designed correctly. If it's not designed correctly, bad things can happen. Most of the time, the reactor always, you know, foot jays around criticality, if it's a pressurized water reactor, like one in my example, right? It's always kind of self-regulating. It always pushes it back to this equilibrium. However, if you somehow can crank this k minus 1 well above zero, make it highly positive, we are going to... So I put this big, fat line between the two things because this is the only analogy between nuclear reactors and reactors. I don't want...