Art McDonald – Nobel Prize Winning Update

One of the criticisms that I hear from time to time, and it's a constructive criticism, is that we hear speakers here over the years and then they disappear, at least from our consciousness. And I've heard this point made about the news business in general. Stories flare up and then they're gone and you're wondering, well, what happened? So this session is a series of updates by previous speakers because they are the kind of energetic individuals that brought them here in the first place. They are constantly doing new work or they have reports from their projects as they stand up to the minute. So Art McDonald describes himself as a kid from Great Breton with no musical talent. But he did okay. He did okay. 17 years ago at our inaugural conference, and you'll remember, it was called TED City at the time, Art told us about his facility in Sudbury, how it worked, and what it was that they were trying to find there. In 2015, he was awarded the Nobel Prize for that work, for physics. And in 2016, the Breakthrough Prize. So neutrinos are practically the smallest basic unit in creation. And what they mean to our understanding of the sun and our understanding of dark matter is what I hope Art will talk about in this update, Art McDonald. Good to see you again, Art. Thank you, Moshe. The invitation still stands. Thank you. You remember you invited me to visit. Yes, indeed. You'll have to come underground in Sudbury. I describe myself that way, by the way, because you put me on the same program with Natalie McMaster. Now, compared to that Cape Retiner, I have no musical talent whatsoever. Thank you, Moses, for the opportunity to come back and tell you what's happened in the interim. We have developed, in the first instance, what I was working on back in 2000, which was the Sudbury Neutrino Observatory. It's a way of detecting these very elusive particles that are produced in enormous numbers in the sun and very difficult to observe. But because they are able to penetrate through the two kilometers of rock that is above our detector, it is actually possible to observe the center of the sun two kilometers underground near Sudbury. We've developed this very low radioactivity laboratory, two kilometers down, such that the rock basically shields out the cosmic rays that otherwise make the atmosphere glow through the northern lights, and in fact would make our detectors glow in the same way. The success of SNO has resulted in expanding the laboratory to what is now called SNOLAB. With this lowest radioactivity location, we can study everything from the most microscopic particles through the solar system, the sun, in particular, to the very largest reaches of the universe and the origins of the universe. We do that because, with this very low radioactivity location, we can observe very rare events. We can observe the few neutrinos that come through from the sun. The number of neutrinos that are coming from the sun are enormous. There are billions going through an area the size of a square centimeter, about the size of your thumbnail, right now, coming from the sun, and once an hour, with a detector the size of a 10-story building, we were able to observe one of those neutrinos. So the point of the low radioactivity location is to shield out everything else, so you see neutrinos and nothing else. We can study the neutrinos in order to understand how the sun burns, in order to understand, in fact, our origins, because that's where many of the elements that were made of are produced. We can understand the basic laws of physics. We learn new properties of neutrinos that I'll describe to you later on. We are now in that new snow lab studying what we think are the types of particles that are five times more extensive in the universe than we are, so-called dark matter particles, and I'll tell you more about that as well. Those dark matter particles and neutrinos are important parts of the composition of the universe as a whole, and so we can do very fundamental things. We do it, in the first instance, by studying neutrinos. Now, neutrinos are not a breakfast cereal, as I was told in one case. They're unusual particles. They are, along with electrons and quarks, very basic building blocks. Those are the three types of particles on which we think everything else is built. Neutrinos come in three what we call flavors, electron, mu, and tau neutrinos, and in the so-called standard model, which you heard a lot about last year, for example, and the year before, and the discovery of the Higgs particle, the last element of the standard model, we have something that works extremely well, except, it turns out, in this instance, because it postulated that neutrinos did not change from one of those types to another, and it postulated that they have zero mass, and they cannot have zero mass if they do make such a change, which is exactly what we were able to prove with our measurements here in Canada with an international collaboration. Neutrinos are very unusual because they only feel the weakest of the forces, and so for them, matter is open space. They only stop if they hit the nucleus of an atom or one of the electrons going around it head-on, and so they can go through the distance that light travels in a year, that is about a million billion kilometers of lead, with only a 50% chance of hitting something. So they're great for getting out from the center of the sun, but it makes them very, very difficult to detect. The nuclear reactions that power the sun are the source of these neutrinos, and so by studying the neutrinos from the sun, we can attempt to understand how the sun burns in great detail and test the models for how that takes place. The measurements we made were made at a time when other experiments could only measure the type of neutrinos that are produced in the core of the sun. Those are the electron neutrinos of those three types, and the predictions were way up here, three times what was measured. By using an enormous amount of heavy water, a resource that Canada had, having accumulated it for use in can-do nuclear reactors, we were able to borrow it and use it to measure another thing, which was sensitive to all three neutrino types equivalently. And so this is a measure of the total number of neutrinos reaching the earth, and it matches very well with the number leaving the sun. On the other hand, the type that is produced in the core of the sun, only a third of them survive. Two-thirds of them, demonstrably in our measurements, have changed into muon or tau neutrinos, the other types. We have excellent agreement with the solar model calculations, and less than one chance in 10 million, or five standard deviations in the scientific terminology, that it is not due to a change in neutrino type. And that's what the Nobel Prize was awarded for. These measurements were made in 2001 and 2002, one or two years after I spoke here last. Why should we care about neutrinos? Well, understanding the sun is of great significance, because a number of the light elements, the majority of the light elements, up to about iron, are produced in stars like the sun and stars like it. Carbon, nitrogen and oxygen, for example, are predominantly produced there by a sequence of nuclear reactions. The elements heavier than iron are produced in supernovae, collapsing stars, much more energetic, and therefore able to produce these very heavy elements. It turns out that you can calculate, within factors of four or five, the abundance of each of the elements that we measure in our world, simply by going through the processes that are taking place in the stars and the nuclear reactions that are producing them. It's a pretty remarkable feat to be able to do that, but the science is there to do it these days. These neutrinos also have a tremendous influence on how structure is formed in our early universe, and by studying the sun and understanding very well how those fusion reactions, where light nuclei come together and give off energy to power the sun, we understand it in a situation where everything is held together by gravity. That's a very similar situation to what people are trying to do on earth in order to harness fusion power for the production of electricity here on earth. In this case, you have to have a bottle with no walls, because if the hot plasma at the equivalent to the center of the sun touches the walls, it'll just evaporate it. So magnetic fields are used to turn these charged particles back into the center of the plasma and to make a so-called magnetic bottle. What we've done by showing within about five percent that we know very accurately how to calculate what's happening in this gravitationally confined plasma caused by nuclear fusion, is that the physics is very accurate. It's a prime example where you try to do the basic physics, you learn that, and now you take that to earth to try to produce power for the future. You know you've got the physics right in the middle, design your bottle, and you can potentially be successful in the future. So those are the sorts of ways that understanding things in a basic way can be of value to us here. We're two kilometers down in Valais' Creighton mine, used to be Inco's Creighton mine in Sudbury. That's four CN towers for perspective. In the United States, I usually put an icon up there of the entire state building. Yeah, you heard me right. I have it on good authority from my eight-year-old son when I was a professor at Princeton. He had a trip to New York City with his class, came back and told us, I've seen the entire state building. But this is my Canadian icon. This is what we built. This is a person to scale. 300 million dollars worth of heavy water on loan for a dollar. That's great and good leverage in any market. It's in the biggest Christmas tree ornament you've ever seen. A plexiglass or acrylic sphere put together from 120 pieces that had to be bonded in place in order that they were small enough to go down in that cage, as they call it, that runs in the mine shaft. 9,500 light sensors looking in at it, capable of seeing a single photon of light with about a 25% probability. Somebody calculated it would be capable of seeing a candle on the moon in terms of the very faint amount of light that it was sensitive to. Everything ultra pure. Everyone coming into work taking a shower and wearing lint-free clothing. And we were able to restrict the amount of mine dust in this entire detector to the amount you could pile on that same thumbnail I was talking about. About a gram altogether. So we had really the ultimate in a low radioactivity location. The water in the middle had one radioactive decay per day per ton of water. A billion times purer than tap water. So this is what happens in terms of the process. Neutrino is produced in the core of the sun. Very easily penetrates through the sun, in spite of the dense material there. Heads for the earth. One of the billions that happens to be heading for Sudbury. Past our control rooms and research labs. Down into the mine and produces a faint burst of light that we observe in the center of our detector. To build that was a major engineering effort and construction effort. We had to build basically a ship and a bottle in this big cavity. 34 meters high and 22 meters in diameter. These are the pieces of the acrylic vessel being bonded in place. This is when we were finishing the lower half. You can see the light sensors looking in at the central volume. This is when all the cables, all 9,500 cables were in place. Going to our computers so that we could collect the data. The data that ultimately showed us those results that I showed to you a moment ago. This is the team. Experiments done by universities in Canada and national labs in Canada and United States. Supported very broadly in all three countries and eventually in Portugal as well. A real international collaboration and that's the way big science gets done these days. We now are very successful with that experiment and this fact that you have the lowest radioactivity location enabled us to then go on and build a new laboratory to take advantage of this as we go forward. This is Snow Lab. It's also two kilometers down, same level of snow. There are a whole series of international experiments that are going on there and one of their principal objectives is dark matter detection and I'll mention in a moment. We are actually reusing the snow detector for something we call Snow Plus where we're looking for a very rare radioactivity. Something that has a half-life we think of 10 to the 25 years or greater. So we take 10 to the 27 or 10 to the 28 atoms of a material called tellurium, dissolve it in something that gives off light and we can observe it and we make that measurement. A wide variety of techniques used for dark matter detection. We're just turning on 3,600 kilograms of liquid argon. That's 10 times anybody what anybody has had before in the reported literature. We hope to have 10 times the sensitivity for dark matter particles that has ever been obtained before and it's very exciting over the next month the remainder of the liquid argon is being installed. This is what that detector looks like before the cables were put on. These are all light sensors looking in again for bursts of light. This is a typical floor in the laboratory. It was like that during snow when I was responsible for it and my mother couldn't believe it. I'd never been responsible for anything that looked as clean as that before. So here's Stephen Hawking visiting in 2012. Absolutely amazing individual. Great sense of humor. I think that's how he deals with his handicap in a good way. He was talking about how the radiation in the universe had cooled off to about two degrees above absolute zero. Almost as cold as Sudbury in the wintertime he said. So this is what we're after now. Things that are not understood in the Big Bang theory. We think that from the Big Bang that about 13 and a half million years ago there was an enormous explosion when at that point we were dealing with quarks and electrons and similar particles and the neutrinos and they gradually formed into three quarks into a proton or a neutron. They formed into nuclei. Electrons were added to form atoms and then eventually you form structure. Well there's a big question because we think in the Big Bang equal amounts of matter and antimatter were created from energy. Where is all the antimatter? And we think that from this rare radioactivity that we're going to measure we can figure that out. We know the differences in mass between neutrinos but we don't know the absolute mass and that has an influence on the formation of structure as does dark matter. This is what we think the universe looks like. It's four percent us, twenty-six percent these dark matter particles and seventy percent something called dark energy which is really a modification of Einstein's laws of gravity. There's a little repulsive part in there that can be expressed in these terms. Donald Rumsfeld would love this. We have known unknowns all over the place here for those of you who only the older people in the audience who reacted to that particular comment. But we don't know what the dark matter particles are. We think that they are outside any particle that has ever been observed in an experiment on earth. CERN and the Large Hadron Collider are trying to create them for the first time since the Big Bang. We're trying to observe the ones made in the Big Bang for the first time. So it's an illustrious list is Art McDonald. Hi I'm Art McDonald. I'm a professor emeritus at Queen's University originally from Cape Breton and I attended Dalhousie University and I'm a co-winner of the 2015 Nobel Prize in Physics. People from 22 Minutes have asked me to come in and explain what I and our team did to win this prize. We demonstrated that the flavor of neutrinos produced in the core of the sun, changed into one of the other two flavors, muon and tau neutrinos, as they traveled from the core of the sun to... okay I'm being told I have to make it simpler. Neutrinos are very basic subatomic particles that we don't know how to subdivide any further. Okay they're asking me to dumb it down a little bit. A subatomic particle is smaller than an atom. Atom is a unit of matter. Really you don't know what matter is? Okay neutrinos are like Timbits. Sometimes they're like chocolate, sometimes they're like cherry filled, and sometimes they're like the old-fashioned glazed. I must be the first person that ever won a Nobel Prize in Timbits. It just just shows you that you can be much clearer if you have great script writers. This Nobel Prize thing has been been quite amazing. We also won the Breakthrough Prize, which enabled me to have lunch with Mark Zuckerberg, Sergey Brin, his wife, former wife, Ann Wojcicki. Sergey Brin of course invented Google, Ann Wojcicki, 23andMe, and Yuri Milner. This was a very Hollywood-type presentation in California, and I've never had lunch with 100 billion dollars in net worth around the table. Very nice people, very interested in the science represented by the winners. I got to actually watch the taping of the, it turns out the scientific advisor used to be a student of ours at Princeton, and he gets the science right, and you'll find that on that program. This is the Nobel banquet, and there's me and there's my wife. I'm seated between two princesses, and my wife is seated between their husbands, and it was an incredible experience. Very genuine individuals, and very easy to talk to, and great people. Fantastic experience. Somehow in the process, I can say this in Toronto, it was learned that I've been a Leafs fan since 1953. They used to win back then. I remember when Tim Horton was playing for them. I had a wonderful experience to meet with Matt Sundin and his wife at the Canadian embassy in Boreas Alming, and actually a couple of weeks ago I got their signatures on a Leafs shirt, and a couple of weeks ago I got Wendell Clark's. I'm doing pretty well. Let me just encourage you, if you happen to be in London over the summer, we have an exhibit at the Eyes on the Universe that we have with this tremendous Canadian scientific laboratory that really is a world beater in terms of low radioactivity and the ability to study very fundamental things. So if you have a chance, observe it, and in its initial place, we're